Reuben's Home Inspection Blog

Why the relief valve at the water heater is leaking, and what to do about it

January 22nd, 2012 | 245 comments

Leaking T&P relief valveWhen a temperature and pressure  (T&P) relief valve at a water heater leaks, it’s usually a simple fix; just replace the valve.   These valves cost less than $15, and replacing the valve is a very basic job – just drain some water out of the water heater, remove the discharge tube, and replace the valve.  No big deal.

Unless it starts leaking again.

If a recently replaced T&P relief valve starts leaking again, it probably means that the relief valve is only doing it’s job; it relieving excess pressure in the water heater.  When this happens, the fix gets a little bit more involved.  I’ll explain.

When a water heater heats up the water in the tank, the water expands.  When this happens, the water typically ends up expanding back out the cold water inlet, all the way back to the water supply coming in to the house.  The municipal water supply for the house acts as a gigantic expansion tank… and nobody notices.  This is illustrated in the diagram below.

Natural expansion

What would happen if a one-way valve, or check valve, was installed on the water supply piping for the house?  The water wouldn’t have anywhere to go.  As the water heater heats the water, it expands, which builds up pressure in what is now essentially a closed system.  When the pressure builds up enough, the T&P relief valve on the water heater just does it’s job and relieves the excess pressure by leaking a little water.

Pressure regulator prevents expansion

In Minnesota it’s rare for a check valve to be installed on the water supply line for the house, but it’s fairly common to have a pressure regulator installed.  When the pressure from the water supply coming in to a house is too high, a pressure regulator needs to be installed on the water main, to prevent damage to the plumbing components in the house.  The problem that these regulators can create is that they will act as a check valve; they’ll allow water in to the home, but they won’t allow water back out.  This creates what is called a ‘closed system’.

When this happens, the T&P relief valve for the water heater can leak.  This doesn’t happen every time a pressure reducing valve is installed, but there may be other problems that show up in the house, such as the toilet fill valves randomly re-filling toilets, or faucets chronically dripping.

The Fix  When a closed system exists on the water distribution piping in a home, an expansion tank needs to be installed somewhere on the plumbing system.  This is a fairly simple and straightforward fix; an expansion tank will give the water somewhere to go when it expands, and the T&P relief valve on the water heater will stop causing problems.

Expansion tank installed

This rule also applies to hot water heating systems; when a boiler heats the water in a hydronic heating system, the expansion tank allows for the water to expand without the pressure relief valve leaking.  If the pressure relief valve on a boiler system chronically leaks, even after replacement, it probably means there is a problem with the expansion tank.

5/20/14: For troubleshooting steps, click here:

Reuben Saltzman, Structure Tech Home Inspections – Email – Maple Grove Home Inspector


245 responses to “Why the relief valve at the water heater is leaking, and what to do about it”

  1. Jon Errickson
    January 24, 2012, 2:51 pm


    I see a lot of discharge pipes with that corrosion at the bottom, but they’re not leaking. Does that mean there’s a problem with the TPR valve? Thanks!

  2. Reuben Saltzman
    January 24, 2012, 3:14 pm

    Hi Jon,

    Staining at the discharge tube could indicate a problem with the TPR valve, but if you stick your finger up inside the tube and it’s dry, it probably just means that there was a leak. No big deal.

  3. Scott Warga
    January 29, 2012, 7:53 pm

    You are doing a great job with your blog. It was also nice to see you at Inspection World in Phoenix.

    Keep sharing information from a home inspector point of view, you and your clients will both benefit from it

  4. Reuben Saltzman
    January 29, 2012, 8:06 pm

    Thanks Scott, it was good to see you too. I had a great time.

  5. Nick Wilder
    January 31, 2012, 10:10 am

    Shouldn’t the expansion tank hang below the pipe so the tank will fill water instead of air?

  6. Reuben Saltzman
    January 31, 2012, 2:40 pm

    There’s a bladder separating the two chambers.

  7. Relief Valves
    June 19, 2012, 5:52 am

    Really, i am so glad to view this amazing & informative post. Thanks…

  8. relief valves
    July 5, 2012, 1:01 am

    Really, it’s a informative post. Thanks…

  9. Mike
    July 9, 2012, 7:10 am

    Our neighborhood water company is periodically cutting the main to install meters and is draing our water heater during the day while we are not at home. Not being able to be there to turn off the power to the water heater, It has damaged the elements and now I had to replace the heater. What can I do to prevent this? A check valve with an expansion tank?

  10. Reuben Saltzman
    July 13, 2012, 3:50 am

    Mike – water enters the water heater at the top and leaves at the top; the drain for the water heater is at the bottom of the unit. To drain your water heater from outside the building, there would have to be a crazy amount of siphoning, and some of the faucets inside your house would need to be left open. I think it’s highly unlikely that your water heater was actually drained.

    The easiest way to prevent this from potentially happening would be to turn off the cold water supply to your water heater before leaving your house for the day.

  11. Lenny
    August 1, 2012, 5:10 pm

    Mr. Saltzman, was very glad to find your excellent explanation. Hope, you could answer my question. I do have a check valve on incoming to water heater cold line, preventing water to go back, as well as pressure regulator in the house. I do not have an expansion tank. So, every night the pressure going up to 110 pci, but in the morning it is 50 pci (water-pressure regulator setting). What puzzled me is: 110 pci I see is on cold water line? Last night, I tested it, by disconnecting water heater from the water system – no jump in pressure overnight.

  12. Reuben Saltzman
    August 1, 2012, 5:16 pm

    Lenny – when the water heater heats up, it puts pressure on both the hot and cold water lines. What you’re explaining makes sense.

  13. Lenny
    August 2, 2012, 5:44 pm

    Mr. Saltzman,
    I do understand it, but I thought that hot and cold water together only in the water heater? If all faucets are closed, hot water is distributed to faucets by separate pipes, and water heater segregated from cold water supply line by check valve. I measured hot water pressure overnight – 160 pci maximum, but why and how it is pushing pressure in cold water pipes going to faucets, where I measure it? Should I assume that some of mixing valves in tubs/showers in my house is allowing cross-over hot & cold water?

  14. Reuben Saltzman
    August 2, 2012, 7:34 pm

    Lenny – where exactly is your check valve located? In your first post, you said it was located on the incoming line to the water heater; if that’s the case, and it’s working properly, then I would guess that you’re correct in your assumption that there is some leakage at one of the mixing valves.

  15. Lenny
    August 2, 2012, 9:15 pm

    Mr. Saltzman,
    Thanks again for your reply. I believe the check valve (it is on incoming to the heater cold water line) is working properly – otherwise the pressure in hot and cold water pipes will be the same, as in a case of faulty check valve, the system will not be closed?
    Anyway, I am planning to install expansion tank – now I really start to understand its usefulness! I have a question related to your statement:”The municipal water supply for the house acts as a gigantic expansion tank” – if municipal water pressure for example 120 pci, in the case of pressure water regulator present, and no check valve – the water pressure in hot water tank must reach 120+ pci in order to be pushed out into municipal water? So, if my logic is correct – expansion tank is a must?

  16. Reuben Saltzman
    August 3, 2012, 4:37 am

    Gotcha. Where are you located? You keep mentioning ‘pci’ for water pressure, but here in the US we call it ‘psi’ – Pounds per Square Inch. Are these the same thing? What does the relief valve on your water heater say? Is it rated for 150 pci? If so, they’re the same thing.

    If they’re the same thing, 120 pci water pressure from the street is extremely high compared to what I normally see, and yes, the pressure in your tank must exceed that for the municipal water supply to act like an expansion tank. I’d say an expansion tank is a must in your case.

  17. Lenny
    August 3, 2012, 5:30 am

    Mr. Saltzman, it is psi (I am in GA) – sorry for my error. And, you just put a final dot – we have probably between 110-120 psi at night time. Thinking about it – my T&P relief valve is probably working (the pipe after that valve is going to a small pump, as it is in a basement). So, it is probably working every night (I hope) to release some pressure in the hot water tank.

  18. Rande
    August 24, 2012, 7:26 pm

    I have a quick comment. In your diagram of the expansion tank installation, it shows the tank before the cold water shut off valve at the inlet to the water heater. I have always seen it required to be AFTER THE SHUT OFF VALVE. This to protect the hot water system in case the cold water inlet valve was shut off (but the water heater still on). This is not a likely situation BUT is possible by mistake.

  19. Barry
    September 26, 2012, 6:37 pm

    Mr. Saltzman, I have a 50 gallon gas water heater, without a pilot light. Several times in the last month, we’ve found our water to be cold. When going downstairs to inspect, I noted a red flashing light on the electronics box. On the side of the box was a switch I proceeded to switch off and back on. After about 60 seconds something kicked in and the flame lit up and began heating again. What is going on with this? Is there something that needs to be cleaned?

  20. Reuben Saltzman
    September 26, 2012, 6:51 pm

    Barry – please send me a few photos of the outside of your water heater.

  21. Ray
    September 27, 2012, 5:08 am

    I’m having a similar problem with a dripping TPR valve. What worries me, is that the water heater is less than a year old and it just started dripping yesterday. Should I be concerned and call our maintenance department?
    Thank you

  22. Reuben Saltzman
    September 29, 2012, 4:55 am

    Ray – yes, you should call your maintenance department. It’s not normal for this to leak.

  23. mary
    October 10, 2012, 6:33 pm


    The tube connected to the TP Valve is leaking so much water. It’s the tube that leads towards the outside of my home. It leads no where else. all the water is just leaking out… is that normal?

  24. jim
    October 13, 2012, 9:24 pm

    i pressed the needle valve on the bottom my expansion tank for the water heater, and let the pressure out. (was showing my daughter, and thought there wouldn’t be an issue…… foolish assumption). anyway, would no pressure in the exp.tank cause the hot water tank to leak at the pressure valve??? i’ve been reading different blogs, and it seems all i need to do is remove the tank, and add the proper pressure needed…..Yes/no????? thanks, jim

  25. Reuben Saltzman
    October 14, 2012, 4:57 am

    @mary – no that’s definitely not normal. You should call a plumber.

  26. Reuben Saltzman
    October 14, 2012, 4:59 am

    @jim – yes, no pressure in the tank would probably cause the pressure relief valve to leak. Yes, just add the pressure needed to your expansion tank and hopefully your problem will be solved. If your pressure relief valve still leaks after that, the valve itself might be fouled and in need of replacement.

  27. Deidre
    October 15, 2012, 9:30 pm

    Rueben, here’s a doosey: I replaced my leaky pressure relief valve, but when I turned on the water again on top of the water heater (before igniting the pilot light), I could hear water pouring out of the exterior drainage pipe! (I live in CA where the drip tube must exit to the exterior of the house). I’m at the end of my rope, and you are my last hope…why is it doing this? Thx so much for your advice!

  28. Deidre
    October 15, 2012, 9:43 pm

    Additional comment, Rueben…if I cover the exterior draining pipe hole, the water is heavily under pressure and spews! It isn’t just a gravity leak…it’s under pressure! Thx so much, I miss hot water! ;-)

  29. Reuben Saltzman
    October 16, 2012, 3:41 am

    Deidre – by “drainage pipe”, I assume you mean T&P relief valve discharge tube, right? If so, the valve is open, you have a defective T&P relief valve, or you installed the wrong valve. Pressure relief valves for boilers are set to got off at 30 psi. If you accidentally put one of those in, it will just leak like crazy. Look for something on the tag that says “150 psi” to make sure you used the right valve.

    If by “drainage pipe” you mean a tube or pipe connected to the water heater drain (located at the *bottom* of the water heater), your drain is open or you have a defective drain valve.

  30. Deidre
    October 16, 2012, 11:40 am

    Rueben, you are a genius!! My replacement TP Valve WAS defective…the new one is now in and my no-longer-leaking hot water heater is filling up with hot water for my first hot shower in three days!! There are no words for me to be able to properly express how grateful I am to you. YOU ROCK!! :-)

  31. Aaron
    October 18, 2012, 9:45 pm

    Rueben, I have replaced a water heater that was bottomed out. I installed new water heater, new expansion tank. The old water heater was always leaking at the tp drain tube. the new water heater is leaking at the drain tube, the leak is very small and not always leaking. I thought that when I installed the new expansion tank the leaking would stop. But it did not, this is a new water heater with new TP valve. What should I do? I did not do anything to the exspansion tank as far as air pressure, installed it with the air pressure that was in the tank from factory. Help please!

  32. Reuben Saltzman
    October 19, 2012, 3:39 am

    Hi Aaron,

    The pressure tank needs to be pre-charged before you install it. The pressure in the tank needs to match the pressure in your system. Watts sends their tanks pre-charged at 20 psi, which wouldn’t be enough pressure for pretty much anybody. You can read about this here – .

  33. Dave
    October 22, 2012, 9:35 pm

    Hello. I turned off the water to the entire house at the main supply prior to going on a 4 day vacation. Does that mean that I have now created the closed system you described above such that water may very well leak from the T&P relief valve? I did set the water heater to the Vacation setting. When I came back from my vacation, all was fine. I turned the main supply back on. However, the next day, alot of water leaked out of the T&P valve. Did I cause this or is this just a coincidence?

  34. Reuben Saltzman
    October 23, 2012, 3:37 am

    Hi Dave, that was probably just a coincidence. I’d replace the T&P valve.

  35. jon t.
    October 23, 2012, 10:08 pm

    The valve located at the back of my house started leaking so I replaced it with a new one.the New valve started leaking after a few days.

  36. Ryan
    November 1, 2012, 11:33 am

    Hello Mr. Saltzman,

    I believe after reading your blog here that my water heater may need an expansion tank. The water heater is fairly new and it was last serviced 2 years ago. The tank started dripping from the pipe coming of the relief valve. I am assuming the valve is working properly as its releasing the pressure. Along with this issue of water dripping from the tank, I also am experiencing chronic dripping from the bathroom faucet and the toilet water will continue to fill up with water randomly. Could this be because of the pressure building up and which I would need the expansion tank?

  37. Reuben Saltzman
    November 1, 2012, 5:11 pm

    Hi Ryan,

    Yes, those things you’re describing are almost certainly the result of pressure building up. An expansion tank should fix this.

  38. Irene
    November 2, 2012, 6:44 am

    I live in an apartment and my pressure reducing valve (I believe it’s called) behind the fridge was dripping constantly for a month and got steadily worse and worse until it wrecked my hardwood floors. Now today, it just stopped. Does that mean that there was too much pressure in my pipes and now it’s been regulated? Or is the pressure reducing valve broken and needs to be replaced? Or that it was working perfectly, hence the dripping? There is some corrosion/rust on it. Thanks

  39. Irene
    November 2, 2012, 6:45 am

    Btw, I should mention that it is on the main pipe, and not attached to my boiler.

  40. Reuben Saltzman
    November 2, 2012, 7:09 am

    Irene – please send me a few high quality photos of what you’re talking about.

  41. Reuben Saltzman
    November 4, 2012, 1:39 pm

    Thanks for sending the photos. I’ve never seen a pressure reducing valve that looked like that, but I’m quite certain that you have a defective pressure reducing valve. It’s not supposed to leak.

  42. Latosha
    November 6, 2012, 12:53 pm

    We had a power outage for 4 days due to Hurricane Sandy. When the power came back on the pressure relief valve started releasing a lot of water. It’s been happening since Friday although it’s not as much water as it initially was when the power came back on. Could the power outage have caused this? Is there something that I can do or should I just call a plumber?

  43. Reuben Saltzman
    November 6, 2012, 8:13 pm

    Latosha – I can’t think of any reason why a power outage would cause the pressure relief valve to leak. Replacing a pressure relief valve is probably something best left to a plumber, but on the other hand, it’s not very complicated if you have some plumbing experience.

  44. Irene
    November 7, 2012, 3:27 am

    I forgot to mention that I live in Europe, that’s probably why it looks different. Thank you for your time and advice, I really appreciate it.

  45. William Byelick
    November 7, 2012, 5:54 am

    In the past couple months I’ve noticed that my T&P valve leaks when I after I use the hot water. I replaced the T&P valve and the one way/check valve entering the home from the municipal water.(set at 50 PSI). Neither has resulted in solving the problem. I’m confused on 1) why this has just started? 2) What else can I do?
    Is installing a preasure tank the only option?
    I’ve checked the preasure on the outside faucet and it reads 40 PSI.

  46. William Byelick
    November 7, 2012, 6:40 am

    Part two: The preasure coming out of the water heater is only 70 PSI and drops when I let water out before building back up to 70 PSI. The prease before entering the one way check valve is 110 PSI. I hope this helps you directing me on how to resolve.

  47. Reuben Saltzman
    November 7, 2012, 6:49 am

    William – you say the pressure from the street is at 110 psi, the valve is set to 50 psi, the pressure coming out of the water heater is 70 psi, and the pressure at the outside faucet is 40 psi? I don’t understand why you have four different pressure readings. I don’t have any insight as to why this just started, or any ways of fixing your leaking valve short of installing an expansion tank.

  48. Sandy
    November 9, 2012, 2:44 pm

    Can a gas pipe hang 2 feet above the water heater? Will it be dangerous?

  49. Reuben Saltzman
    November 9, 2012, 5:39 pm

    Hi Sandy,

    Yes it can, and no, having a gas pipe 2′ above a water heater isn’t dangerous. Is there a specific situation you’re wondering about? Do you have a photo you’d like to send me?

  50. shelly
    November 13, 2012, 6:39 pm

    Please help,
    We had a leak coming out periodically frpm the PRV, but we got and installed a whole new water heater w a new valve as well, now we have had it about 2 months, and the kitchen flooded a bit again because the PRV leaked again (theres no outlet just a pipe that we put a bowl under, the bowl overfilled & leaked all over kitchen), my husband checked pressure on main line and found it was open all the way, could this be the problem? if he reduced it to halfway could this possibly fix the problem? or do we have to buy an expansion tank? we cannot afford it right now, and we live in CA by the way

  51. Reuben Saltzman
    November 13, 2012, 8:08 pm

    Hi Shelly,

    The pressure coming in to your house isn’t what’s causing the problem; the problem is probably the result of a check valve or pressure reducing valve that’s acting like a check valve. Expansion tanks are not expensive.

  52. shelly
    November 13, 2012, 8:11 pm

    thank you, okay where are those valves located? i only know of the water heater PRV that is attached to the water heater? Do i need an expansion tank?

  53. Reuben Saltzman
    November 13, 2012, 8:30 pm

    Shelly – probably right by your water meter. In CA, I think it would be located somewhere out in your yard. Here in MN, it would be located in your basement.

  54. shelly
    November 13, 2012, 8:33 pm

    thanks again, okay so you believe the check valve by the main line might be the problem? do i need to replace that valve? or does the water company? or do i just adjust it? sorry so many questions i truly appreciate your help.

  55. Reuben Saltzman
    November 13, 2012, 9:04 pm

    Hi Shelly,

    I recommend you re-read this post. I’m guessing the problems is that you need an expansion tank.

  56. beth
    November 14, 2012, 6:33 pm

    Just replaced our hot water heater and a new relief valve. Every time I use the hot water the valve leaks. It is driving me crazy. Had the water company check the pressure they adjusted it to 70, and put a regulator in yesterday. Today the valve is still leaking. What is going on. Thanks.

  57. Reuben Saltzman
    November 15, 2012, 4:49 am

    Hi Beth, it sounds like you need an expansion tank.

  58. David Hamill
    November 20, 2012, 9:16 pm

    Excellent summary with great information. I recently replaced my expansion tank and now my cold water pressure relief valve is leaking water – about a gallon per week. Is this a result of too much pressure in the expansion tank? If I lowered the pressure (with the valve on the tank) would this reduce the leaking? (I replaced the pressure valve thinking it was faulty, but it did not fix the leaking).
    Thank you.

  59. Reuben Saltzman
    November 21, 2012, 4:53 am

    David – I’m not positive, but I’m pretty sure what you’re describing could happen if the pressure was too high or too low at the expansion tank. The tank should be set to the same pressure as the water in your home before it’s installed. See my comment to Aaron on 10/19.

  60. Amy
    November 26, 2012, 11:26 am

    we recently had a TET installed on the cold water line. this was to replace a TET that was broke and had been installed incorrectly on the hot water line. the plumber left the old TET (broken) on the hot water line and just added a new one on the cold water line. this was supposed to fix our leaking relief valve. it still leaked. so he replaced that last week… and today it is still leaking. however – i see water marks running down the entire pipe – like its leaking out at the top or something. so frustrating!

  61. Paul
    November 26, 2012, 10:21 pm

    Water is leaking from the relief valve on my water heater. The breaker is also tripping. The insulation on cover for the lower element was real wet and there was rust around the nut of the element. I checked the voltages on the themostat and elements and they are fine. I also olmed out both elements and they checked out ok. The water heater is 11 years old. Time to replace or can it be repaired?

  62. Reuben Saltzman
    November 27, 2012, 4:43 am

    @Amy – sounds like it’s time to call your plumber again.

    @Paul – I’m no expert on repairing electric water heaters.

  63. David
    December 2, 2012, 2:29 pm

    My 10 yr old gas water heater began leaking from the T&P valve on thursday, leaked during the day on friday, we have used hot water since then and the water heater has been running as normal, now the T&P valve is not leaking is that good or bad? I leaked very little though maybe 2 glass fulls, we do have an expansion tank connected to it as well.

  64. Reuben Saltzman
    December 3, 2012, 4:45 am

    David – it sounds like your expansion tank isn’t functioning properly. Check to see if the pressure is set properly.

  65. Jeanne Simonin
    December 6, 2012, 1:40 pm

    The water dept recently completed some major water pipe replacement. They had me set up with a by-pass. Once the by-pass was removed and water was again going through my water meter, The pressure regular pipe began leaking. My hot water is much hotter than it use to be before this major work was done. Should I call the water dept or a plumber? What could have caused this?

  66. Jeanne Simonin
    December 6, 2012, 1:41 pm

    Let me add, that the pipe replacement was only done at the street. Nothing was done in my yard.

  67. Reuben Saltzman
    December 6, 2012, 3:01 pm

    Hi Jeanne, I don’t know why that would have any effect on your water temperature. You should start by turning down the temperature at your water heater. If that doesn’t fix it, call a plumber.

  68. Michelle
    December 19, 2012, 11:33 pm

    Mr. Saltzman, Good evening. I’ve recently moved into a home and our water consumption was very high. I had a leaks in several different areas which I have located and replaced but my consumption is still very high. I often hear sounds like water is running in the wall between the two bathrooms. I made sure all facets and toilets were turned off and then checked my meter. The small dial on meter was still turning which if I am correct indicates a leak. I proceeded to turn off all the actual connections and not just the faucets which did not stop the dial on the meter. I then turned off the cold water that is going into the water heater and the sounds of running water behind wall and dial on the meter ceased. Could you please provide me with some ideas that would help me to determine the cause of the leak (tpv, check valve, broken pipe, need for expansion tank)? Any ideas/suggestions would be greatly appreciated as I am single mother of 3 children and do not have the funds to hire plumber or another high water bill and my landlord is not interested in helping.
    Also, how is it possible to use more gallons in sewer charges than my children and I consume? Example, my water bill says that we have consumed 10,000 gallons of water and used 35,000 gallons for sewer? Those numbers are most likely not exact since I cannot find my water bill but do remember them being very different. I also remember the charges for water were like $39 and sewer was $70. Thank you so very much for reading this and for any ideas/suggestions you may have.

  69. Reuben Saltzman
    December 20, 2012, 4:45 am

    Hi Michelle, where are you located? What type of home is this? Where is your water meter located? Do you have water piping that runs below the ground? Can you see the existing water heater?

  70. susan
    January 1, 2013, 6:11 pm

    Hello. I accidentally pulled the release valve at the top of the pipe when doing laundry. Water came rushing out and flipped the toggle switch back down. However, the hot water heater has since starting leaking from the top. Someone told me I messed the pressure up in the tank. How do I fix it?

  71. Reuben Saltzman
    January 2, 2013, 5:46 am

    Hi Susan,

    No, you didn’t mess up the pressure in the tank. Just replace the valve.

  72. Debbie
    January 4, 2013, 10:20 pm

    Hello! I have been having water water leak out out the T&P valve so today I replaced it but I just went down and there was water in the container I have beneath the pipe attached to the valve. There is an expansion tank on the system which is just a couple years old, the water heater itself is about 5 years old. You mentioned checking the pressure in the expansion tank, how do I do that? What should it be at? I have no idea what I am doing and I am starting to wonder if I should contact a plumber. I have been trying to avoid having to do that as I am a parent with a single income and I try to do as much as I can myself but I don’t want to make things worse either. A friend of mine had told me not to keep waiting as she has heard of tanks exploding. One last thing, the one day the water was quite rusty but that was the only time.

    Thank you.

  73. Milan
    January 6, 2013, 6:03 pm


    I live in California and have a pressure regulator attached at the incoming line just as it enters the house. From what I understand , these valves create a closed system …is this correct ?

    Also, I have a Maytag 50 gallon water heater. It recently started leaking from the top. Thought is was the outlet (hot water) piping but that was not the case. It is oozing water from around the area that the hot water nipple extends out from the heater. But it is not leaking from the actual nipple fitting itself. Also , when I pull in the lever for the TPR valve there is no egress of water. Sounds like the TPR valve is bad and the leak from top is possibly due to water /pressure expansion. …. correct ??
    I do not have a expansion tank in place and we have not had any problems with the TPR valve being activated in the 20+ years we have lived in the home. Why would this happen all of a sudden. The only other change that was recently made was that the previous water softener was engaged. IT was on bypass mode for the last 2 years as it was malfunctioning. However, previously we used it for years and there were no problems. Please advise.


  74. Reuben Saltzman
    January 6, 2013, 8:39 pm

    The pressure regulator might create a closed system; some do, some don’t.

    Yes, it definitely sounds like you have a defective TPR valve that should be replaced, but what you’re describing doesn’t sound like a pressure problem; it sounds like you may have a defect with your water heater. I would check to see if this is covered under your water heater manufacturers warranty.

  75. Reuben Saltzman
    January 6, 2013, 8:48 pm

    Debbie – use a tire gauge or something similar to check the pressure at the valve on the expansion tank. The pressure should be the same as the municipal water supply.

  76. Chad
    January 10, 2013, 7:25 pm

    Hey Reuben I have the exact situation.

    A new gas w.h. several moths after install the pressure relief valve started leaking.

    I changed pressure relief valve and it is now leaking too.

    I believe there is a pressure reducing valve on main supply.

    There is an existing expansion tank as well.

    Did not test the expansion tank as this issue is new to me.

    I suppose the expansion tank could be bad or maybe the pressure in the tank is not right.

    Could that be my issue and what is the proper pressure for the expansion tank in regards the the house pressure.

    Thanks, Chad :)

  77. Reuben Saltzman
    January 11, 2013, 4:30 am

    Hi Chad, I think you’re right. The pressure in your tank is probably too low – it should be the same as the water in your house.

  78. lynn
    January 11, 2013, 11:51 am

    I have a 4 year old gas water heater that is part of a hydronic heating system. 2 times in the couple of weeks I have notice some water beneath the pipe that drains to the outside from the temperature and pressure relief valve. My system does have an expansion tank above it. Is it normal for water to be expelled periodically from the T & P valve pipe like this periodically when the heat is being heavily used during the winter? I have never tested the T & P value – should I? Should I call a plumber to have it checked? The hydronic heat piping system looks very complicated – looks like I have an octopus coming out of my hot water tank ;-)

  79. lynn
    January 11, 2013, 12:26 pm

    Please note – the amount of water expelled looked to be less than a half cup each time it happened. thank you for your insight!

  80. Reuben Saltzman
    January 11, 2013, 1:46 pm

    Hi Lynn, no it’s not normal for water to expelled. Yes, you should have a plumber check this out.

  81. Mike D.
    January 24, 2013, 6:53 pm

    Due to my relief valve leaking, I put a new one in. It started leaking shortly thereafter. I have an expansion tank, so I’m guessing that might be the problem based on what I’ve read from other posts here.
    You’ve told others about matching the water pressure in the expansion tank to the pressure in the main line. I understand how to check the pressure in the expansion tank, but how do I check it in the main line? Also, if I need to add pressure to the expansion tank, how do I do that? With a bicycle pump?

  82. Reuben Saltzman
    January 25, 2013, 5:06 am

    Mike D – you can check the pressure in your house with a pressure gauge; they’re sold at home improvement stores for about $10. I have never worked on a pressure tank, so I’m not the best person to ask for advice. Try asking Mark the Plumber – he does a Fix-it-Friday on his facebook page, where he answers your plumbing questions every Friday. He’s the plumbing pro.

    If it were my own house, I’m sure I would be trying a tire / bicycle pump.

  83. Angela
    January 26, 2013, 9:59 am

    Last night we had low water pressure due to a house fire on the next street over being fought. This morning the PRV on my hot water heater is dripping a small amount. Could this be caused by low water pressure?

  84. elizabeth kaylor
    January 27, 2013, 9:14 pm

    Ours is leaking…we would like to repair it ourselves but it specifically says on the water heater that if it leaks to call a plumber. What would the reasoning be? Would it be safe to replace ourself?

  85. Reuben Saltzman
    January 28, 2013, 5:24 am

    Angela – no, low pressure wouldn’t cause a leak in the valve, but the change in pressure may have been enough to make a valve that was on the verge of failure fail.

  86. Reuben Saltzman
    January 28, 2013, 5:26 am

    Elizabeth – the reasoning is that you could create a very unsafe situation if you don’t perform the repairs properly.

  87. Janet
    January 28, 2013, 6:06 pm

    Hi Reuben,

    Our water mgmt co says that I have a leak going downhill into a neighbor’s yard. Apparently a lot of water is running thru my system, but I see no leaks anywhere in the house, under the house or in the yard (we have yet to install meters on this system that serves about 54 homes).

    You can hear water gurgling at all of the cold water faucets, the water heater (which is in a little basement) as well as a drain in the lower landing of my outdoor stairs to this basement and also at the shut off valve on the county property in front of my place.

    Apparently this leak has been going on for some time. I am hearing impaired, so I was unable to hear it at all, but have had someone from the water mgmt co come and listen – plus a neighbor did the same a couple days ago.

    The water mgmt co thinks I need to have someone dig up my property to look for this leak. I am not sure who to call for help. Could it be something to do with the way that the water heater is installed?

    If so, should I call a plumber, Roto Rooter or whom?

    Thank you for any info. Love your blog!


  88. Reuben Saltzman
    January 28, 2013, 8:29 pm

    Hi Janet, it sounds like the water main to your building is leaking underground. This probably won’t have anything to do with your water heater. Your best bet would be to call a plumber.

  89. Dan
    February 10, 2013, 9:10 am

    Hi Reuben,

    I have a tankless water heater/boiler with an expansion tank that started leaking at both tp tubes (heat and hot water) From what I have seen in these posts is that I likely have a problem with the expansion tank. I have well water with a pressure regulator set to cut in at 30psi and cut out at 60 psi. What should the water heater expansion tank pressure be? Would draining it completely reset the pressure?


  90. Reuben Saltzman
    February 10, 2013, 9:42 am

    Hi Dan,

    I have never worked on a pressure tank, so I’m not the best person to ask for advice. Try asking Mark the Plumber – he does a Fix-it-Friday on his facebook page, where he answers your plumbing questions every Friday. He’s the plumbing pro.

  91. Angela
    February 10, 2013, 11:02 pm

    Recently we have been having issues with very high pressure in the faucets when we turn on the water. It only lasts a second, then the pressure is back to normal. This comes and goes, I haven’t called anyone since it may not hapen when they come out. I’ve also noticed occasional leaks from the pipe on the side of the hot water heater, with the TPH valve. After reading your comments, I’m wondering if these are related problems. What do you think?

  92. Reuben Saltzman
    February 11, 2013, 4:40 am

    Angela – yes, these definitely sound like the same problem. I recommend you get a plumber out to correct this.

  93. RHO
    February 12, 2013, 1:14 pm

    I am curious about replacement of Expansion tanks. Here in Washington, every time I have replaced a water heater the techs insist that we replace the expansion tank also. Do expansion tanks require replacement every time you replace a water heater? How much heavy lifting do they do, that they should be replaced each time? I have had salesmen tell me that it is a waste. I would like to know what you think or know.

  94. Reuben Saltzman
    February 13, 2013, 4:52 am

    Hi Rho,

    I have never worked on a pressure tank, so I’m not the best person to ask for advice. Try asking Mark the Plumber – he does a Fix-it-Friday on his facebook page, where he answers your plumbing questions every Friday. He’s the plumbing pro.

  95. Angela
    February 17, 2013, 8:29 pm

    A plumber replaced the T&P valve because it was leaking. It is still leaking. Any ideas? .The water heater is atleast 10 yrs old.

  96. Reuben Saltzman
    February 18, 2013, 5:05 am

    Angela – did you read this post?

  97. andrea
    February 23, 2013, 8:14 pm

    I don’t know much about water heaters but ours is leaking. The t&p valve is on top of the water heater and water fills up in the space where the valve screws into the water heater. My dad just changed the t&p valve and it looks like its still filling up with water. I am an onsite property manager and live in a upstairs apartment. The water heater is gas and is an a.o. smith. Im not sure how old it is. Please let me know if you can help.

  98. Reuben Saltzman
    February 24, 2013, 7:05 am

    Hi Andrea, it sounds like either the t&p valve wasn’t properly replaced or the water heater itself is leaking. Your next step would be to contact a plumber.

  99. Sam
    March 1, 2013, 5:27 pm

    Hi Reuben,

    I have an unvented electric water heater system that supplies us with hot water. I noticed 6 weeks ago that my shower mixer was leaking from inside the wall. I could hear it at about 11pm. Approx 30 mins after economy 9 had turned the element in the tank on. I rent so contacted the letting agent who sent a handyman. He has since failed to understand or diagnose the problem.

    Is there any obvious things it could be? PRV on the tank? Incoming pressure to high? Tempreture of element too high?

    Also do you think this is cost me much? There is a drip every 3 seconds.

    Hope you can help.

  100. Reuben Saltzman
    March 1, 2013, 8:32 pm

    Hi Sam,

    The most obvious issue would be a defective shower valve. Excessive pressure could also lead to the leak; have the pressure inside the house checked, and have a plumber make sure you don’t have a ‘closed system’.

  101. Danny Mitchell
    March 2, 2013, 12:13 am

    I purchased two GE Gas water heaters within two months of each other and both of them started leaking at almost the same time.. I replaced one pressure relief valve with no change.. I had heard that there was a rash of Bad Pressure relief valves from China That GE had installed into several thousand water heaters.. so when I called the Company they said it is normal for your water heater to lose some water when it goes through a heat cycle..thats just so much B/S .. while water does expand when heated.. never have I had the occur on two water heaters at the same time.. I am going to check the incoming water pressure but it doesn’t seem to be over the limit..

  102. Ram
    March 9, 2013, 8:30 pm

    Hi Reuben,
    I read your blog, you mentioned about ‘toilet fill valves randomly re-filling toilets’. I live in Virginia where the Thermal expansion tank is not necessary in my county I checked this.

    I have my TPR recently started to release some water then go away but happens once in while. It never happened before. This started after I installed dual flush system in my toilets replacing ALL floating ball systems. Before that (replaced the flush systems) I used to hear water dripping sound in one of the toilet. Now that dripping has been gone but the TPR valve stareted releasing water at the water heater.

    I checked the pressure at the Water heater drain it is 50 PSI and also checked at the laundry room faucet (cold water) 50 PSI there too. The Pressure reducing vale tag says set to 50 PSI.

    I haven’t replaced TPR or installed Thermal expansion tank. I am wondering if adding the Thermal Expansion tank is the only option or (cheap way) put back one of the floating ball flush see if it goes away?
    Since there is not continuous dripping at TPR valve I am guessing the TPR is still good. I think I just created total closed system with dual flush systems. What are your thoughts?

  103. Reuben Saltzman
    March 9, 2013, 9:10 pm

    Hi Ram,

    No, a thermal expansion tank isn’t your only option. You could install a toilet fill valve that has a built-in pressure relief, such as this one . I didn’t mention this in the blog post because it’s not an ‘approved’ method of dealing with thermal expansion in a closed system, but it would probably work just fine.

    If you happen to put one of these in, let me know how it works. I’ve never actually seen one of these, only heard about them.

  104. Ram
    March 9, 2013, 9:33 pm

    Thanks Reuben. I will give a try to see if it works.

  105. Russ Harding
    March 9, 2013, 10:08 pm

    I installed a brand new electric water heater today. The problem I’m have is that the t&p valve is leaking. Do to this leaking I changed it two times thinking it was defective. Still leaks. I replace the old 40 gal water heater with another 40 gal water heater. It starts leaking as soon as the tank fills up (water temp is still cold). Do you think an expansion tank would fix this problem? I thought that expansion tank work when the water gets hot? Could I have a bad pressure regulator? What are your thoughts?

  106. Reuben Saltzman
    March 10, 2013, 1:52 pm

    Hi Russ, it sounds like you have a problem with the water pressure in your house that isn’t related to thermal expansion. Get a pressure gauge and test the pressure; it should be below 80 psi.

  107. Steve
    March 12, 2013, 6:22 am

    Reuben, I just replaced my expansion tank with a new one. Old one had failed after 10 years. I checked my house water pressure and precharged the expansion tank to match (40 psi.) I did open the TPR valve to make sure it was working. Now I have noticed a small drip from the TPR valve. Is it possible the TPR did reseat correctly? Should I just change the TPR valve? Thanks

  108. Reuben Saltzman
    March 12, 2013, 7:26 am

    Hi Steve,

    Yes, it sounds like you need a new TPR valve.

  109. lisa
    March 13, 2013, 1:19 pm

    question: brand new tank (propane) installed and of course new relief valve. When tank fills after showering the valve leaks and about 1/2 fills a coffee can. We live in a mobile home and the town
    is on a closed system. We have never had an expansion tank, town states I shouldn’t need one unless we have a above 90 pressure (which he says we don’t) or boiler, etc. We don’t have room for an expansion tank in the tiny spot this tank is in. Tested valve and it’s doing it’s job. What is the problem? thanks

  110. Reuben Saltzman
    March 13, 2013, 2:01 pm

    Lisa – how did you test the valve? I’m guessing you have a bad valve. Try replacing it.

  111. lisa
    March 13, 2013, 2:04 pm

    By opening the valve for 8-10 sec and the letting it snap back to close. and may I add I have the wter temp set at medium settings are only low, medium and high and I know high is way too hot
    and low isn’t hot enough

  112. Reuben Saltzman
    March 13, 2013, 2:40 pm

    Gotcha. Try replacing the valve.

  113. Steve
    March 18, 2013, 7:01 am

    Replaced the TPR valve, solved the problem. Thanks!

  114. Bob D.
    March 18, 2013, 4:56 pm

    My water heater relief valve started leaking about a gallon every 3-4 days, so I replaced the valve. The new valve did not correct the issue. I finally decided to upgarde my water heater and the new tanks releif valve leaks just the same (about a gallon every 3-4 days). I leve in the county and my water cutoff valve is located a couple hunderd yards down the drive near the street. I do not know what my presssure regulator is set at (I actually live out of state).
    I’m at my wit’s end. Is an expansion tank installed between the cold water supply valve and the tank the best answer?

  115. Reuben Saltzman
    March 18, 2013, 5:06 pm

    Bob D – yes, probably so.

  116. J Richards
    March 18, 2013, 7:13 pm

    Around 4 a.m. our water stopped, hot and cold. Shortly after the water came back on 20 min later I heard spray and found the t/p valve on our electric water heater was spraying, I turned off the water and electricity to the tank and have now replaced the t/p valve (evidently there has been a run on them at the local building supply stores) and the new valve leaks as soon as I turn on the water supply and fill the tank even though it is not plugged in and the water is cold, The leak stops when I turn off the water supply. Any help is appreciated.
    Thanks again in advance.

  117. Reuben Saltzman
    March 18, 2013, 7:47 pm

    J Richards – I’m guessing you picked up the wrong valve; a pressure relief valve for a boiler is set to go off at 30 psi, and it looks nearly identical. If that’s not the case, you probably have a defective valve.

  118. matt
    March 30, 2013, 4:03 am

    i am attempting to install a T&P valve on my own. Are there any precautions I should take when installing it? And how do I know the T&P valve was properly installed? I dont want to blow up my house.

  119. elliott
    April 1, 2013, 10:26 am

    Ruben, not long back our well was producing higher pressure spurts of air and mixture of water that had high amounts of rust… or so it appears to be. But since it subsided quickly and the rust color went away we thought almost nothing of it.

    i think April first is like a full moon day, here’s why: after waking early in the morning and then doing a few dishes after preparing coffee, i heard the sound of our toilet running. After turning off the local water supply behind the bowl and trying to formulate a list of the tools i might need to repair it (while the clock reads 5:30am) i hear thru my early morning brain fog (we have all been there) a slow but steady drip drip drip coming from the hot water heater. The T&P valve was running and the drip was unabsorbed water by the insulation blanket. Hot water supply valve off immediately. Then the single control for hot/cold water faucet in the kitchen cannot be stopped after running some noticeably higher pressure cold… i realize that i’m out of my sleep fog and have stepped into a fools day episode of the twilight zone as i turn off the water supply where it enters our house, kill the power to the well pump and the water heater. Now after reading a bit about other people’s difficulties, i’m not sure who i should call because i know the well company (now bankrupt) installed a ‘pressure tank’ between the well and our house. Maybe a pressure problem, maybe a failing relief valve, maybe a failing kitchen faucet and or toilet fill valve were affected after all is said and done will i need to replace those also? i tried to add as many details as possible sorry if there is too many.

    Thank you for your time.

    ps i built the house and did all the interior plumbing but the well i could not, and this is beyond my abilities, thus my questions.

  120. Reuben Saltzman
    April 1, 2013, 7:35 pm

    Elliot – your first step should be to measure the pressure of your water and make sure your tank is properly charged, and also make sure it’s not waterlogged. My best guess is that this was just a bad coincidence.

  121. elliott
    April 1, 2013, 8:21 pm

    Thanks Reuben, and plz excuse my misspelling of your name in my earlier entry. i have had a well installation and repair gentleman come to the house and he listened to the problem looked around and thought my variable high pressure is because the buried pressure tank valve is no longer working… epic failure! Way to much pressure incoming and the various valves inside the house broke or worked properly as the case may be. He recommended an internal pressure regulator made by the wellmate company after all the power supply lines needed have been made available (gitrdone!). Does this sound correct, to me (layman) it does sound correct. The pressure box, all the fittings and needed connections and of course the labor will come to less than 820 dollars to me that also sound reasonable since just the wellmate box is 350. Plz let me know if this sounds even just a wee bit funny, but i will have him check the pressure levels before any installation begins on friday. The defective pressure valve on the buried pressure tank will be removed once the ground thaws for an additional price. Once again, thank you very much for your time and attention to my post.

  122. Reuben Saltzman
    April 2, 2013, 3:47 am

    If this is the best that can be done until the buried pressure tank is accessed, you’ll probably have to do it. It makes sense.

  123. elliott
    April 3, 2013, 12:11 pm

    thank you Reuben for helping me and my situation. you are truly a gentleman and a scholar and there are very few of us left. have a fantastic day!


  124. Paul Lotts
    April 22, 2013, 7:37 pm


    I have a leaking T&P value on my 2 yr old gas water heater (very minor dripping out my pvc pipe to the exterior of the house – none inside). According to your posts, I should replace it. I’m leaving on vacation in a few days and can’t do it. Should I shut off the cold water supply as a precaution without I’m gone?

  125. Reuben Saltzman
    April 23, 2013, 3:44 am

    Paul – sure, that couldn’t hurt. You might also want to turn the temp down on the water heater.

  126. rolando
    April 24, 2013, 9:17 am


    My neighbor is having issues with his gas hot water heater, he’s replaced his relief valve and it still leaks, he doesn’t have a check valve or expansion tank… He is currently turning up the thermostat to full capacity, and he says his hot water runs out pretty quick… my question to you is im pretty sure he needs a new dip tube and maybe a new thermostat? I’m thinking the thermoster is corroded and acting as an insulator wich causes it to read temperature incorrect…

    any help would be greatly appreciated

  127. Reuben Saltzman
    April 24, 2013, 1:05 pm

    @rolando – You’re probably right. I’d say it’s time for your neighbor to get a new water heater. I’m guessing it’s at the end of its life expectancy.

  128. ao smith water heater manual
    April 24, 2013, 5:10 pm

    Instead of circulating hot water around to keep it warm
    even after it’s heated, residents who own tankless water heaters in Mishawaka, IN can simply heat water as it comes through for your use. There are several types of choices for solar hot water systems. The problem with traditional water heaters in the home, however, is that there has been only so much room to store heated water.

  129. mike
    April 24, 2013, 6:28 pm

    Hey friend accidentally bump the water heater valve and a little bit of water came out and I cleaned the water up but now the valve is leaking does this mean I will have to replace the whole valve or should it stop leaking on its on thanks any help would be much appreciated thanks mike.

  130. Reuben Saltzman
    April 24, 2013, 7:36 pm

    Hi Mike, it’s probably just going to keep leaking. I recommend you replace it.

  131. jerry
    April 29, 2013, 10:16 pm

    Hello, I had a faulty T&P valve, which would leak from time to time, I replaced the valve, but as soon as I turn the water supply on, water comes gushing out from the top of the valve. The leak is much worse with the new valve then the old one. I have tried plumbers tape, didn’t slow down the leak. It is a side mount. Also I put the old valve back on just to see and it now leaks just as bad as the new one too. It is like there is something wrong with the threading of the thing you screw the valve into. No matter how tight I screw it, it still leaks the same.

  132. Reuben Saltzman
    April 30, 2013, 3:50 am

    Hi Jerry, it sounds like you might need a new water heater. I would have a plumber check it out before replacing the water heater though.

  133. vanessa gibbs
    May 7, 2013, 4:27 am

    I have a gas hot water leak on the exterior of my house, the water smokes and appears to be very hot the floor inside my house close to that area is hot as well, what could this be, could it be dangerous

  134. Reuben Saltzman
    May 7, 2013, 4:48 am

    Hi Vanessa, it sounds like you might have a leaking pressure relief valve. Yes, this could be dangerous. You should contact a plumber ASAP.

  135. Jon
    May 12, 2013, 8:22 pm

    Hi Rueben,
    After reading all of the posts I’m guessing the answer is to install a thermal expansion tank on the hot water heater cold water pipe inlet, but I’ll let you confirm that. My setup is the following: main cold water pipe to shut-off valve to pressure regulator/reducer valve to two branches – 1st) pressure relief valve (75 psi) opening up to open space (i.e. no overflow piping) and 2nd) hot water heater cold water inlet (there is no expansion tank).
    Problem: I’m getting ready to sell my house and noticed that the pressure reducing valve was extremely corroded and leaking. I had this replaced by a plumber and the plumber suggested to replace the pressure relief valve (located just after the pressure reducer) as well since it had a slow drip. Those parts were replaced and unfortunately the dripping didn’t stop, it got worse. At certain times during the day it will increase in frequency and at other times the dripping will cease. I was toying with the idea of finding a way to connect overflow piping to the relief valve and emptying out to the sump pump, but this won’t fix the leaking; it will merely route it to a safe place. As I am needing to put my house on the market this next week (and need home inspectors to not raise a red flag) how would you recommend fixing this leak? Thermal expansion tank? Or will a slow drip at the relief valve be acceptable to home inspectors? I want to minimize expenditures and modifications to the plumbing where possible.

  136. Reuben Saltzman
    May 13, 2013, 3:42 am

    Hi Jon,

    You got it. You should install an expansion tank.

  137. Jon
    May 13, 2013, 3:50 am

    Thanks Rueben. Any idea how much an expansion tank install should cost (parts and labor)? It would be helpful to know when I call around for estimates.

  138. Reuben Saltzman
    May 13, 2013, 5:23 am

    Hi Jon,

    I’ve never priced it out, but my best guess would be $200 – $300.

  139. William Cunningham
    May 13, 2013, 9:05 pm

    my hot water heater is leaking around the outside edge of of where the pressure valve screws in,not the threaded part for the valve, but the outside of that part next to the tank itself.Can that fitting be replaced or is that the end of my heater

  140. Reuben Saltzman
    May 16, 2013, 3:58 am

    William – I’m pretty sure that’s the end of your water heater.

  141. Geoff H.
    May 19, 2013, 1:47 am

    The drain tube from my TP relief valve is leaking and water ran into the room next to the water heater. There is a steady leak of water out the tube. For a temporary fix for the water running into the next room I extended the tube so it runs down the drainage tube in the room. Do I need to replace the TR relief valve or is it a bigger problem? If it is just the valve is it safe to replace on my own if I follow the instructional videos I found online?

    I’m located in Utah.


  142. Reuben Saltzman
    May 19, 2013, 5:08 am

    Geoff H – did you read this post?

  143. James
    June 13, 2013, 10:23 pm

    I replaced a leaking tp valve and almost a month later it is leaking again.The house we bought had a leaking water pressure reg outside and the plumber eliminated it could high pressure cause it to leak and if so could I just back the shut off valve up a little to reduce pressure in the pipes. Thanks

  144. Reuben Saltzman
    June 14, 2013, 4:06 am

    James – High pressure coming in probably wouldn’t cause a leak. Partially closing the main valve would only reduce water flow; not pressure.

  145. Selena
    June 16, 2013, 8:39 pm

    Our water heater was leaking from the pipe hanging downwards. My husband pulled up the valve to ensure that sediment was not preventing the full closure of the release, and it seemed to stop it for a couple of weeks. It just started leaking again. Does this sound like a simple valve replacement? Thanks!

  146. Reuben Saltzman
    June 16, 2013, 9:23 pm

    Selena – replacing the valve should be your first step.

  147. Moe
    June 17, 2013, 7:24 pm

    Is it ok to install the expansion tank on the hot water line near the hot water heater or does it have to go on the cold water line?

  148. Reuben Saltzman
    June 18, 2013, 6:16 am

    Hi Moe, I’m not sure. I would have to read through the manufacturers installation instructions.

  149. John
    June 26, 2013, 5:19 pm

    I am getting ready to replace my 40 gal. hot water heater and i don’t know why there are 2 lines coming out of the T&P valve. There is a tee fitting on top of the heater and the T&P valve is on the top with a line going in the wall and another line out the other part of the tee going in the wall Why?

  150. Reuben Saltzman
    June 27, 2013, 3:33 am

    John – if you have a very old water heater, the T&P valve might be plumbed in through the hot water line. If that’s not it, I’m not sure.

  151. kenny
    June 28, 2013, 11:47 pm

    I replaced a leaking compression fitting valve and a faucet in an apartment and the next day the t&p valve gave out and will not hold pressure. The water heater is about 3 years old.Is it something i done wrong with the plumbing?

  152. Reuben Saltzman
    June 29, 2013, 5:05 am

    Kenny – the leaking faucet might have just been the weakest link. Now the T&P valve is just doing it’s job and relieving excessive pressure.

  153. biniam
    July 1, 2013, 8:04 am

    Hi Reuben. I replaced my water heater tank. Now, I have a tiny leak at the valve. I do have an expansion tank, as in before. I tried to resolve this by trying to undo the TPR valve and either replacing it or applying Teflon tape on the threads as I forgot during the installation. I loosened it about 180 degrees but I couldn’t go furthers as it is really tight and it’s squeaking. I put it back together without turning the valve back to where it was. The leak was gone for a while but there is even now a smaller leak than before. What do I do now?

  154. Reuben Saltzman
    July 1, 2013, 10:30 am

    Biniam – did you re-charge your expansion tank after replacing your water heater?

  155. Biniam
    July 1, 2013, 10:49 am

    Reuben, that might be my issue there. What’s to re-charge an expansion tank? No idea about that. So the answer is no.

  156. Biniam
    July 1, 2013, 11:25 am

    Reuben, that might be my issue there? What’s to re-charge an expansion tank? No idea about that. So the answer is no.

  157. Biniam
    July 1, 2013, 11:27 am

    Would simply replacing the expansion tank work too?

  158. Reuben Saltzman
    July 2, 2013, 3:44 am

    Biniam – your expansion tank should have a small valve on it called a Schrader valve. You can use a bicycle pump to re-charge the pressure tank to make sure the pressure inside it matches the pressure of the water in your home.

    To check the pressure of the water in your home, you need a pressure gauge. If the pressure in the tank doesn’t match the pressure of the water, the expansion tank won’t work properly.

    For more detailed info on this, you should locate the installation instructions for your specific expansion tank and follow the manufacturers instructions.

  159. Biniam
    July 2, 2013, 9:30 am

    Thanks for the input Reuben. One last post and I will try the steps on my day off tomorrow and let you know the results. So you don’t think not having wrapped the threads on the valve with Teflon tape and perhaps not putting it there properly may be causing the small leak? I borrowed a pipe wrench and I was going to remove it and re-install it. The leaking water doesn’t even make it above the depression where the valve sits by the way but the fact that there is water there worries me. Also, there is a pressure gage already in my water line so things are a bit easier for me there.

  160. Reuben Saltzman
    July 2, 2013, 1:21 pm

    Biniam – is the leak coming from the threads or coming out of the opening at the t&p valve?

  161. Biniam
    July 2, 2013, 1:39 pm

    Reuben, the leak is coming from the threads. The leaking water doesn’t even make it over the depression on the tank where the valve is attached, on top of the tank. There’s no leak anywhere else.

  162. Reuben Saltzman
    July 2, 2013, 2:05 pm

    In that case, the leak is surely the result of a bad connection to the water heater. Wrapping the threads will probably fix your problem.

  163. Biniam
    July 4, 2013, 6:37 pm

    That’s it, problem solved. I wrapped the threads on the calves with teflon and there is no more leak. Thank you!

  164. biniam
    July 4, 2013, 6:42 pm

    I meant valve not calves on the previous post,my smart phone is not so smart sometimes.

  165. Scott
    July 6, 2013, 12:31 am

    I have an 11 year old house with gas water heater (75 gal). I have copper plumbing in the house. I noticed the last week or two a sound of “rushing water through pipes” that could be heard from inside the house on the wall where the water heater resides in the garage. The wall is also warm to the touch where the water heater is (warm on the garage side wall and house side wall). I noticed quite a bit of water under the water heater as well. I shut off the water supply to the house, drained the water tank, turned the water back on, continued to drain (looked clear, no sediment..on city water for house good quality). I tested the T&P relief valve and it seems to be operating correctly. When in the middle position, water runs freely from the valve. With the water to the house on, and water to the water heater shut off, I still get the sound of rushing water. When the house water supply is shut off, the sound stops. Any ideas of what to do next? I never notived this sound or the felt heat on the wall in my 11+ years of living here.

  166. Reuben Saltzman
    July 6, 2013, 5:45 am

    Scott – It sounds like you have a leak that probably isn’t related to the water heater. Check your water meter to see if there is water flowing when it shouldn’t be. If so, you have a leak somewhere, probably in the wall.

  167. Scott
    July 6, 2013, 11:01 am

    YEP! bad section of 3/4″ copper pipe…had a pinhole leak. Had to cut out a section of drywall about half the size of a doorway, cut and replaced the pipe, and now all good. Just need to let dry and get a drywaller in to finish the job. Good blog and great info here!

  168. Dave
    July 9, 2013, 5:35 pm

    The pressure relief valve on my gas hot water heater is dripping. The system also has an expansion tank which I think may be waterlogged. Is there a way to add air to the expansion tank? If so, how do I add air to the system and how much should be added? The expansion tank specs list Air Pre-Charge as 20 PSI, Max Air Charge as 80 PSI, and Max Working (Water) as 150 PSI.

    Thank you for your assistance.

  169. Dave
    July 9, 2013, 5:37 pm

    The pressure relief valve on my gas hot water heater is dripping. The system also has an expansion tank which I think may be waterlogged. Is there a way to add air to the expansion tank? If so, how do I add air to the system and how much should be added? The expansion tank specs list Air Pre-Charge as 20 PSI, Max Air Charge as 80 PSI, and Max Working (Water) as 150 PSI.

    Thanks for your assistance

  170. Reuben Saltzman
    July 10, 2013, 3:37 am

    Dave – your expansion tank should have a small valve on it called a Schrader valve. You can use a bicycle pump to re-charge the pressure tank to make sure the pressure inside it matches the pressure of the water in your home.

    To check the pressure of the water in your home, you need a pressure gauge. If the pressure in the tank doesn’t match the pressure of the water, the expansion tank won’t work properly.

    For more detailed info on this, you should locate the installation instructions for your specific expansion tank and follow the manufacturers instructions.

  171. Shawn Macedo
    July 11, 2013, 7:56 am

    Thanks for the great information on your blog. This article was just what I was looking for!

  172. Marco
    July 30, 2013, 12:04 pm

    Is it necessary to have a drainage line coming out from your t&p relief valve?

    Mine is located on the top of my water heater, and there is no drainage line attached to it. No water is leaking from the t&p valve though.

    My concern is will my house be flooded if the t&p valve does release water?

  173. Reuben Saltzman
    July 30, 2013, 1:54 pm

    Marco – yes, there should be a discharge tube attached. You can read more about it here:

    The T&P valve typically won’t release water suddenly; it’s usually more of a slow leak.

  174. Steve
    July 31, 2013, 12:23 pm

    Hi Reuben,

    We had found a small amount of water nearby our gas water heater every three/four days for two weeks
    now. Our plumber just replaced the T&P valve last
    week. We could not find any leaking from the water tank. Is it possible that the water came underneath
    the concrete floor? Thank you for your time.


  175. Dave
    August 1, 2013, 10:47 am

    The pressure relief valve on my gas hot water heater was dripping water on a system that has an expansion tank which I thought may be waterlogged. I turned off the water main, drained part of the system, and attempted to add air to the expansion tank. However, after adding air, I am not getting a pressure reading at the Schrader valve. Is this an indication that my expansion tank is defective and needs replaced?

  176. Reuben Saltzman
    August 1, 2013, 2:29 pm

    Dave – air is supposed to be added to the expansion tank when water is already in the system. If it won’t take pressure after that, yes, it’s probably defective.

  177. jeanne
    August 4, 2013, 11:18 pm

    If we had a discharge about [a gallon], then the discharge stopped, do we still have to replace the pressure relief valve? Thank you so much

  178. Reuben Saltzman
    August 5, 2013, 4:10 am

    @jeanne – personally, I would replace it.

  179. Carol
    August 5, 2013, 4:55 am

    Our six year old Whirlpool Gas Water Heater has decided to stop working. The pilot light will not light. We have an Expansion Tank and have noticed that on the pipe leading to it there is a build up of rust. Also the top of the Water Heater has a spot where it looks like it is rusting and has a hole. I can see rust stains as if the pipe was leaking but never actually saw it leak. So my question is is it time for a new heater? Is there something that needs to be replaced?

  180. Donnie
    August 16, 2013, 9:42 pm

    I have a 40 gal Hot Water Tank and the T/P valve is leaking after replacing it a year ago, I tried turning off the cold water at the inlet, but it continued to leak. My next step was to turn the water back on and turn the thermostats (both) all the way down to 90 deg. I left it that way for a day and checked the water temperature to insure that the thermostats are working properly. They appear to be just fine: nothing but warm water! The T/P valve was still leaking however. I also checked the pressure at an outside faucet and found it reading about 75 pounds. With the T/P Valve leaking continually however, I am thinking that it may be defective, or it could be excessive pressure at 75 pounds. If the problem is the incoming pressure, what are my options? An expansion tank will just fill up with water due to pressure and the t/p valve will start leaking again once the expansion tank reaches capacity, right? Replacing the T/P valve won’t remedy the pressure problem either will it? HELP!!!

  181. Reuben Saltzman
    August 17, 2013, 5:15 am

    Hi Donnie,

    Before doing anything, I would try replacing the T&P valve again.

    An expansion tank will not fill up with water; it has a bladder that allows air to compress inside it. If the valve leaks again after replacing it, contact a good plumber.

  182. Eugene
    August 20, 2013, 7:20 pm

    I hope I am not asking a question previously ask. I recently replaced the drain valve on my gas water heater. Prior to the replacement, I operated the heater on A for several years and moved it between A and B about one year ago. Since replacing the valve, I have to operate the heater on B to satisfy my family. We have been in the home for 11 years and prior to replacing the valve I performed zero preventive maintenance (I did not know it was required). I drained the water heater during valve replacement and also learned from the manual TODAY my water heater requires annually the temperature pressure relief value be manually open.
    Does the requirement to increase the setting indicate an issue, will opening the pressure valve help? Thanks in advance.

  183. Reuben Saltzman
    August 20, 2013, 7:33 pm

    Hi Eugene,

    You’re probably having to turn up the temperature dial because the thermostat is covered in sediment; this happens over time. Testing the pressure relief valve won’t affect that.

  184. Eugene
    August 20, 2013, 8:48 pm

    Reuben, thanks for the prompt reply. There are no additional leaks since replacing the drain valve. Would draining the water heater again (done once in 11 years) help with the thermostat sediment issue? Or, would you recommend replacing a thermostat in a 1998 model? During the repair, I did vacuum off the burner. It had a lot of black sediment piled on top of it…

  185. Reuben Saltzman
    August 21, 2013, 3:32 am

    Draining the water heater now probably won’t make any difference; it needs to be done regularly from the start. I would just plan to replace the water heater soon; water heater are expected to last for about 10 – 15 years.

  186. JayMar
    August 24, 2013, 5:54 pm

    I have a 6 year old Lochinvar 50-gal gas water heater (model no: LTN050G-4) that is not producing hot water and there is water filling up in the drain pan as I don’t ever recall water being in there before. The relief valve discharge line has a steady drip of water into the pan which has filled the pan to almost full. There’s no corrosion anywhere and the PRV looks normal.

    What steps should I take to resolve the steady drip of water into the pan from the PRV discharge line before reigniting the pilot light? And is it safe to reignite the pilot light if water is dripping from the PRV discharge line?

  187. Reuben Saltzman
    August 25, 2013, 12:40 pm

    @JayMar – replace the T&P relief valve. Yes, it’s safe to re-ignite the pilot even if the T&P relieve valve is leaking.

  188. Val
    August 26, 2013, 6:58 pm

    Thank you for this site. We just replaced a 19 year old water heater that dripped just a bit from the relief valve. We have since reduced the pressure in our home to 45psi (from about 100) so we were surprised to find that the new heater is dripping more than the old. Not only is it dripping but it seems like during the day when we’re at work it “throws up” water because there is much more water on the floor than a drip should cause. We’ll be replacing the Pressure Relief Valve in hopes that is all we have to do. Fingers crossed!

  189. Donna
    September 1, 2013, 1:56 am

    Hello. We just installed a new Whirlpool Gas hot water heater. Filled tank with water and then PRV begin leaking/spewing to the point we had to shut it off at the cold water supply valve off. That stopped it. But it was too late to go back to the store. Could the PRV be defected on new water heater? We did go down in size from a 50 gallon to 40 gallon short. Thanks in advance for your expertise!

  190. Reuben Saltzman
    September 1, 2013, 5:41 am

    Hi Donna, yes, it’s possible that your water heater came with a defective T&P relief valve. It’s even more likely that it’s stuck in the open position.

  191. Donna
    September 7, 2013, 10:02 am

    Reuben, replaced the T&P relief valve and viola, works like a champ. Thanks for your help!

  192. evee sue
    September 7, 2013, 3:46 pm

    I live in a condo, the water heater is enclosed in a closet with a pan . My water heater leaked, (about >10 years old), and the plumber adviced me to replace it with new one, but he said he need to upgrade it, he said the new plumbing code requirement is to have the discharge pipe extended to the outside of my unit. he will use approx. 30 feet pipe. Is this a new plumbing code?

  193. Reuben Saltzman
    September 8, 2013, 6:26 am

    @evee sue – there is no requirement in Minnesota for the T&P discharge tube to discharge to the exterior of the home. The Minnesota State Plumbing Code says “The discharge pipe shall be full size and run to within 18 inches of the floor or a safe place of disposal.”

    If you’re outside of Minnesota, you’ll need to check your state plumbing code.

  194. Mike Widmer
    September 16, 2013, 5:41 am

    Must of been Saturday night sometime, while I was at work. My wife came down the basement Sunday morning to feed the dog, when walking over by the dog food, almost half of the basement was water. 1) did the water come from the pressure relief valve. 2) is the tank leaking somewhere? Now, today is Monday, I am sitting in the basement, typing you this, ran all our showers for 10 minutes, and so far, nothing is happening. What should I do?

    Mike W

  195. Reuben Saltzman
    September 16, 2013, 8:26 am

    Hi Mike,

    Stick your finger up inside the T&P discharge tube. If it’s wet, there’s your culprit. If not, I don’t know what it was.

  196. Carol H.
    September 17, 2013, 9:43 am

    Glad I found your site! Hopefully you can help me, I’m trying to save replacing my water heater as a very last resort. A couple of months ago, our gas water heater started leaking from the top. We drained it completely and then refilled it. No problems until today. Today, when my husband started getting ready for work, we discovered there was no hot water. Went downstairs to find water on the floor, minor compared to the first a few months before. I opened the PRV to let some of the water out, let it go for about a half an hour and then closed it again. It is making a sound kind of like a hiss, if that makes any sense. So, I turned off the level on the pipe above the water heater, as my husband told me to do. The leak and the hissing sound both stopped instantly. I will be checking it around noon my time (it is 9:41 in the morning right now) to see if the water is heating up.

    I live in Colorado, and we have had a lot of rain over the last week (I’m sure you all have seen the news about it). While we were not hit by any flooding, I mention this in the event it might be related. I appreciate any info you can give. Thank you so much for this blog!

  197. Reuben Saltzman
    September 17, 2013, 1:59 pm

    Hi Carol,

    It sounds like you probably need a new water heater.

  198. Paul
    October 13, 2013, 8:59 pm

    After a remodel I noticed that a pipe is now welded to the heater relief valve and it appears to feed plumbing for a bathroom. I tried it see if the valve would activate and pushed fairly hard but can’t budge it. I’ve never tested one before so I’m afraid to pull the lever too hard. This appears to be a dangerous adaptation. I live in nevada. Is this a valid setup that meets code?

  199. Reuben Saltzman
    October 14, 2013, 3:33 am

    Hi Paul,

    That sounds like an unsafe setup. I’m not familiar with Nevada plumbing code, but whatever it is, I’m sure your setup doesn’t meet it. Get a plumber to fix it.

  200. Kevin
    October 20, 2013, 8:47 pm


    I tested my T&P valve tonight as the directions called for annually (just bought the house last month and not sure when it was last tested) and it has been dripping for a few hours now since I tested it. It did not drip before I tested it, now I’m regretting doing it. I turned off the the water supply to stop the dripping over night. We where also out of town for the past week, not sure if there is excess pressure from not using the hot water for that long or if the valve just needs to be replaced? Do I need to hire a plumber to do that?

  201. Reuben Saltzman
    October 21, 2013, 3:33 am

    Kevin – the valve needs replacement. You can find youtube videos of how to replace the valve; that might help you decide whether you need a plumber.

  202. Chad
    October 27, 2013, 7:25 am

    my relief valve keeps leaking after replacement. ive never had this problem before. my wife said she had seen standing water out by our incoming line. i have yet to see the standing water come up but my question is If there is a blockage or something in the main line would that cause my relief valve to leak?

  203. Chad
    October 27, 2013, 7:59 am

    Ive actually noticed that it only leaks whenever she takes a bath and the tank starts to fill back up

  204. Reuben Saltzman
    October 28, 2013, 3:39 am

    @Chad – no, I’m sure there’s no blockage in your main water line that could cause the relief valve to leak.

  205. scott
    October 29, 2013, 6:49 pm

    Replaced hot water heater due to old one leaking out bottom. Now the new hot water heater leaks water outof the pressure valve. I have an expansion tank already. The old hot water heater never leaked. What do you think is the problem. I tried turning the temperature down. And that didn’t help

  206. Reuben Saltzman
    October 29, 2013, 7:18 pm

    @Scott – you probably need to charge the pressure tank. See my comment to “Biniam” on 7/2/13.

  207. scott
    October 29, 2013, 7:31 pm

    So i need to recharge the expansion tank to match hot water heater pressure its an older expansion tank so I don’t have the manual is there a common procedure for this. Also is that the reason I don’t have the water pressure in the shower as before with the new heater.

  208. Sarah Tooke
    November 4, 2013, 8:53 am

    My husband replaced the relief valve and thermostat on the hot water heater, and it’s fine for awhile then the relief valve starts leaking water and there is a lot of steam coming from it. What can we do to fix this?

  209. Reuben Saltzman
    November 4, 2013, 8:57 am

    @Sarah T – It sounds like you have a defective water heater. What is the temperature of the water when this happens?

  210. Bob
    November 12, 2013, 9:32 pm

    My T&P valve was leaking. I checked the water pressure coming into house and it was 100 psi. Between the cold water shut-off and the water heater, I installed a Pressure Reducing Valve, a pressure gauge and an expansion tank. The reducing valve and the tank were set at 50 psi and the gauge confirmed that. The leaking stopped for one month and started again. I noticed the gauge sometimes reads 80 or 90 psi and sometimes 50 psi. I closed the cold water inlet valve and the gauge went to 0 psi. I left it closed for 1 hour and then checked the gauge and it read 75 psi. So, I seem to be getting a backflow from the hot water line that has high pressure and causes the leaky T&P. How do I fix this problem?

  211. Reuben Saltzman
    November 13, 2013, 4:31 am

    @Bob – I’m no expert at troubleshooting situations like yours, but my best guess is that you either have a defective or improperly installed expansion tank. You’ll have to talk with a plumber for more info.

  212. James
    November 17, 2013, 7:28 pm

    T&P valve has a constant flow coming out. I’ve turned down the temperature on the water heater, adjusted the house’s water pressure to 60psi, installed an expansion tank and adjust it to 58psi, and replaced the pressure relieve valve, yet it continues to leak. Anything else I can try?

  213. Reuben Saltzman
    November 18, 2013, 4:34 am

    @James – if the house pressure is at 60 psi and water constantly comes out, it means the valve is open, the valve is defective, or the wrong valve is installed. Make sure the valve is set for 150 psi and 210 degrees (f).

  214. Water Heater Repair in Miami FL | Water Heater Repair Miami
    November 28, 2013, 8:31 am

    […] water heater can have too much pressure inside if your T&P valve is not working properly. This valve is responsible for releasing pressure build up that protects […]

  215. Scott Simpson
    December 3, 2013, 6:30 pm

    For the first time in 10 years I opened the release valve on my water heater. I have never had an issue, a leak or any issue with it prior. Now the copper drain tube from the release valve will not quit leaking water. Does that mean my valve is defective and will not close now that I opened it.

  216. Reuben Saltzman
    December 4, 2013, 4:31 am

    @Scott S – yes, that’s a common occurrence when someone tests one of those valves that hasn’t been operated for a long time. Time for a new valve.

  217. Tim
    December 8, 2013, 10:07 am

    I recently bought a house and the water heater wasnt giving me much hot water, about enough for a 5 minute shower. I called the home warranty and they came out and flshed the system and got out a lot of sediment. He mentioned that they cannot replace it until it actually is leaking. A few hours after he left I noticed that the T&P was leaking quite a lot, about the same amount that comes out of a bathroom sink when turned on. Do you know why this would happen and how I can fix this? The water heater is very old and does need to be replaced but I was hoping to hold off a little while

    Thank you for your help

  218. Reuben Saltzman
    December 9, 2013, 4:31 am

    @Tim – I’m guessing the T&P valve was operated, which could cause an old defective valve to start leaking.

  219. Brandon Baker
    December 13, 2013, 9:30 pm

    Hey Mr.Saltzman looked all over the web for a blog like this and im hoping you will be able to help me i have a pressure regulator coming in on the main water supply and an expansion tank before the hot water heater…today after two showers i was in my basement (having a smoke) and i hear alot of water running i look and the pressure relief valve is discharging all over…filled the pan by the time i got it to stop and all over the floor (atleast 3 gallons) could this just mean that the valve is going bad? or the expansion tank? and what causes the tank to go bad? its a new home and was installed no later then 3yrs ago..any help would be appreciated

  220. Brandon Baker
    December 13, 2013, 9:32 pm

    expansion tank was what i ment in the last post

  221. Reuben Saltzman
    December 14, 2013, 5:55 am

    @Brandon – yes, this could be a bad valve, a bad tank, or the tank might not be charged. Read through the previous comments to see what I mean about the expansion tank not being charged. The tank has a bladder that separates the air from water; if the bladder fails, the expansion tank has failed. That’s not too likely on a three-year-old system.

    If the pressure in your expansion tank matches the water pressure, replace your relief valve.

  222. L
    December 21, 2013, 11:52 am

    the water dept was completing a repair and apparently some debris made its way to our PRV valve and we had significantly reduced water pressure. We are waiting on a plumber to fix it but in the mean time I wondered if using the little water pressure we have to shower will damage our hot water heater? Thanks!

  223. Tara Herbert
    December 23, 2013, 4:31 pm

    Dear Mr Saltzman,
    Your blog is so great. I too have a question. My tpv started leaking…..initially a big flow of very hot water. I think it was my fault as I noticed the boiler pressure was low and let in more pressure. Then I left the boiler running on high and went out for a couple of hours. When I got back I heard the water rushing out through the Tundish and through the relief pipe to outside. I checked the boiler and saw the pressure was up to 3 bar. So I drained some water through a radiator to get the pressure back down to 1.5 bar. However water continued to come though the tpv for the next 8 or 9 hours …less over time. I turned off the boiler and switched off the power into the tank. Eventually the water went to a drip and now it’s stopped. I need To go away for a few days over Christmas and the plumber is coming straight when I get back. I will leave the boiler and power off as its not freezing weather. My big question is shall I switch off the mains water or not? There is no cut off for water directly into the tank I can work out so its mains or nothing. Just frightened to do the wrong thing. THanks so much.

  224. Reuben Saltzman
    December 23, 2013, 9:00 pm

    Hi Tara, once you have added water to the system, the fill valve should be shut back off, and you shouldn’t have to worry about more water coming in. It doesn’t sound like you have an automatic fill valve, so you should be safe leaving the water on. Without seeing your system I obviously can’t guarantee that, but that’s my best guess.

    If there is a valve that adds water to your boiler system, it should be turned off.

  225. Tara
    December 24, 2013, 1:05 am

    Thank you so much! Happy Holidays!

  226. Andy McDonnell
    December 27, 2013, 3:28 pm

    So I changed Pressure relief valve on water heater but had strange problem. After turning off cold water input and draining about 15 gallons, the relief valve still flowed water when opened. I drained 15 more gallons, opened a HW faucet, and bled all pressure by holding relief valve open. Two minutes later I removed the old valve and warm water kept gushing out, until I was able to thread new relief valve into place, soaking me and dumping a few gallons of warm water onto the floor.
    MY question is, where did that water come from? Back flow from the hw piping? It was warm, not cold, and high in the tank.

  227. Paul DE
    December 28, 2013, 11:13 am

    Thanks so much for the information! I replaced my heater with the exact same model and size as the original about 8 months ago and everything has been fine until now. My relief valve that came on the new one has been driving me nuts for a couple weeks now. It has been so intermittent I actually had to put a plastic cup under the pipe to make sure that is actually where it was coming from. It is. I can dry everything up and watch it for about 8 hours, through people taking showers, and doing dishes. Everything will be dry. Then, randomly, there will be an inch of water in the pan. I haven’t been able to find a pattern. I think the relief valve is bad, but I need to ask a question. There is an expansion tank installed in the cold water inlet line that sits above the pipe. That means that the air section would be above water section. When I drained the water heater the expansion tank drained too. I didn’t do anything special to refill the expansion tank. I just hooked everything back up and turned on the water. Was I supposed to prefill the expansion tank, deflate it, or anything? Instructions for new ones said just pressurize and connect it. I never deflated the bladder pressure on this one. I just left it as it was. Could an air bubble be stuck above the water in the expansion tank causing it not to work right? Also, the outside temp is dropping around here. The inlet water would be colder but the tank itself is under the stairs in the warmer house. Thanks for any help!

  228. Reuben Saltzman
    December 28, 2013, 8:42 pm

    @Paul DE – I’m no expert at troubleshooting expansion tanks; I know just enough to explain the concept. Your theory sounds plausible.

    I’d check the pressure on the water distribution piping in the house, then compare it to the pressure in the expansion tank. If they’re not the same, get that corrected. That should be your first step.

  229. Ahsan
    December 31, 2013, 1:33 pm

    Many thanks for such a nice information which I am sure have helped many across the world.

    Following advices and recommendations, I have replaced the TPR valve to stop the almost constant dripping water. The water has unfortunately not stopped dripping. It ONLY stops dripping when there is hot water being used at home. This is my 6th year in the home. There is no expansion tank installed and some how things were working fine until now. Any recommendations from your side will be highly appreciated.

  230. Reuben Saltzman
    December 31, 2013, 1:41 pm

    @Ahsan – if it still leaks, I’m guessing the wrong valve was installed. Make sure the valve is set to go off at 150 psi.

  231. Ahsan
    January 1, 2014, 11:34 am

    Thanks for the reply. You were right. I installed a wrong valve. This morning I installed a correct one and unfortunately the water is still leaking. Not sure what should I do now. Thanks for your help!

  232. Reuben Saltzman
    January 2, 2014, 4:44 am

    @Ahsan – if it’s still leaking and the correct valve is installed, there are three possibilities: 1) The valve is defective. 2) The pressure in your tank is over 150 psi. 3) The temperature of the water in your tank is over 210 degrees Fahrenheit. If it were me, I’d be checking the pressure in my system.

  233. Ahsan
    January 2, 2014, 8:04 am

    Sounds very logical. Any advice on how to check the pressure in the system ? I have meter installed to Furnace which shows reading of approx 25PSI. I am not sure if this will be the same for Water Heater as well. Thanks a lot for your help !

  234. Reuben Saltzman
    January 2, 2014, 8:18 am

    Put a device like this on the hot water connection for your washing machine.

  235. Ahsan
    January 2, 2014, 7:06 pm

    You are right….the pressure is at almost 160PSI. So how can we reduce this to the desired level.

  236. Paul DE
    January 2, 2014, 8:57 pm

    I put a RainBird pressure gauge I bought at HomeDepot on my washing machine’s cold supply and my pressure reached 160psi after about an hour of not using water. Yikes! Normal pressure was about 58psi. I checked the Schrader valve on the expansion tank and it sprayed water. So, it looks like my expansion tank’s bladder was blown. Without the expansion tank my relief valve was doing what it should at 155psi. Releasing pressure. The instructions for the new tank said it has a bladder instead of a diaphragm which allows it to be installed at any angle. It’s an Amtrol st-5. Online reviews said the cheaper in-store ones fail much more. I installed the new one with 58psi of air pressure and so far my water pressure has been steady at 58psi. My mistake during troubleshooting was not realizing that any water usage will equalize the pressure again. The only time the water pressure would have reached a dangerous 155psi or greater in my situation was after a lot of hot water usage followed by no water usage at all. That’s when the most water is heated and the most expansion occurs without any release. Thanks for sparking the thought process for me!

  237. Ahsan
    January 2, 2014, 10:02 pm

    Tried to reduce the pressure via water pressure reduction valve, but it did not reduced the PSI which is still showing at 160. Could it be that the valve is not functional and need to be replaced ?

  238. Reuben Saltzman
    January 3, 2014, 5:08 am

    @Ahsan – I think that’s exactly what your issue is. Probably a defective pressure reducing valve.

  239. Reuben Saltzman
    January 3, 2014, 5:09 am

    @Paul DE – thank you for taking the time to come back and post your results here. I’m glad to hear you got it figured out.

  240. Jordan
    January 4, 2014, 4:57 pm

    A couple of questions: if you’re water heater has with check valves on the hot and cold nipples leading into the water heater and out of it, how can the pressure tank help with water expanding out of the tank? Also, I noticed that your illustration shows the expansion tank before the hot water heater shutoff valve…most of the illustrations seem to stress it should be between the shutoff valve and the cold water nipple. Does it make a difference? Thanks.

  241. Reuben Saltzman
    January 5, 2014, 6:55 am

    @Jordan – I’ve never seen a water heater with check valves on the hot and cold water nipples, but yes, a check valve on the cold side would render an expansion tank useless. Also, the shutoff valve for the water heater should be located immediately before the water heater. Where have you seen illustrations showing otherwise?

  242. Ahsan
    January 5, 2014, 10:28 pm

    Hi Jordan, I retested the pressure reducing valve….actually it does increase / reduce the water flow pressure (water coming out of the tap) but the water pressure gauge will still hit 160 PSI regardless of the pressure valve setting. So I am assuming that the pressure reducing valve is working however it is still a mystery why there is this higher downstream system pressure (under no flow condition).

  243. Reuben Saltzman
    January 6, 2014, 4:36 am

    @Ahsan – at this point, I think you would do well to have a plumber check it out.

  244. Lenny
    January 6, 2014, 8:56 am


    You do not have an expansion tank or it is not working properly.

  245. Ahsan
    January 6, 2014, 9:19 am

    @Lenny, there is currently no expansion tank installed. It was never there before as well. We do have one for home heating (furnace).

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