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Whole House Humidifiers Harm Houses

By In Humidifiers On January 27, 2009


Whole house humidifiers can cause serious problems, especially in Minnesota.  Sometimes they destroy houses.  This topic gets a lot of people whipped up, and I always hear the same arguments for having a humidifier: they prevent your hardwood floors from cracking and splitting, they make the house more comfortable, you’ll get nosebleeds if you don’t… etc.  I admit, those are all valid arguments.  Nevertheless, the damage caused by an improperly used humidifier can far outweigh the benefits, and humidifiers are almost never used properly.  From all the houses that I inspect in Minneapolis and the surrounding areas, I know this.

A whole house humidifier gets installed in the furnace ductwork, adding moisture to the air that gets distributed throughout the house.  The amount of moisture that’s added is manually controlled with a dial that is usually located next to the thermostat, or next to the furnace.  To maintain the proper level of humidity, you need to know what the temperature is going to be, and then adjust the settings on the humidifier accordingly.  This is why I have such a problem with whole house humidifiers.  Here’s an excerpt from an owner’s manual:

“it is important to anticipate a drop in outdoor temperature and reduce the setting  accordingly to avoid excessive condensation. For example, with an outdoor temperature of 20°F the correct setting will be 35% RH. If the temperature is expected to fall to 0°F that evening, then merely reduce the setting to 25% several hours prior to the temperature change.”

Get out!  Nobody does this.

The biggest problem with whole-house humidifiers is that too much moisture gets added to the air, Moisture Damaged Window and the moisture condenses on the windows, walls, and especially in the attic.  Excessive moisture in the home causes mold growth.  Excessive moisture on the windows stains the finish and damages the wood.  Excessive moisture in the attic causes condensation, which can rot the roof boards.  I’ve inspected many attics with rotted or delaminating roof boards, and in almost every case there was a whole-house humidifier present.

My recommendation is usually to not use whole house humidifiers unless you’re an extremely ‘type A’ homeowner, which means you’ll check the weather forecast and adjust your humidifier all the time.  I do have a bit of good news about humidifiers though- the newest ones come with automatic humidity controls, so you don’t need to adjust the settings all the time.  I learned about these at Aprilaire’s web site, and I think they’re a great idea that will probably save a lot of homes from damage.  If you must use use a whole-house humidifier, use one of these.

Reuben Saltzman, Structure Tech Home Inspections – Email – Minnesota Home Inspector

        



About the Author

Reuben

Reuben is a second generation home inspector with a passion for his work. He grew up remodeling homes and learning about carpentry since he was old enough to hold a hammer. Reuben has worked for Structure Tech since it was purchased by Neil in 1997, and is now co-owner of the company. Reuben’s favorite customers are the ones who have a lot of questions; he grew up thinking he was going to be a school teacher because he enjoyed teaching others so much. In a sense, that’s a lot of what home inspections are about, so Reuben truly does what he loves. Reuben has an A.A. degree in liberal arts and has attended most of the Building Inspection Technology classes at North Hennepin Community College. Reuben and his wife are the proud parents of two young childen, Cy Alexander and Lucy Nicole, and have a German Shepherd named Stanley. With two young children Reuben doesn’t have much free time, but he still tries to play disc golf as often as possible during the summer. Reuben lives in Maple Grove, MN. Professional Qualifications / Memberships: *ASHI Certified Inspector *President, ASHI Heartland Chapter *Member, Minnesota Society of Housing Inspectors (MSHI) *Licensed Minneapolis Truth-in-Sale of Housing Evaluator *Licensed Saint Paul Truth-in-Sale of Housing Evaluator *Licensed Maplewood Truth-in-Sale of Housing Evaluator *Licensed Hopkins Truth-in-Housing Evaluator *Licensed Robbinsdale Point of Sale Evaluator *Affiliate Member, Southern Twin Cities Association of Realtors

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8 Comments

  • Priyanka 11 MONTHS AGO

    The humidifiers are playing an indispensable role in enhancing the moisture level of air. Thus you can prevent a number of diseases with the aid of these humidifiers.

    • Reuben Saltzman 11 MONTHS AGO

      @Priyanka - how does "enhancing the moisture level of air" prevent diseases?