Humidifier Maintenance

I just got an email from the senior home editor for Popular Mechanics asking for some guidance. It’s worthy and timely with the season, so I am including his question and my answer here:

His question:

A reader has emailed me with a couple of humidifier questions. He just
bought a home with an AprilAire humidifier and wants to know what to do with
it in the summer. Aside from the obvious (shut it off and perhaps switch the
damper lever on the duct to the summer setting) what else can I tell him?

He also describes a component that sounds like it’s the humidifier water
panel evaporator. He’s suspicious of the white/gray crust on the panel and
mentions that it’s crumbling. First, can you tell me what the material on
the panel is? Second, I would assume that it’s best to replace the panel, if
not in the spring, then before the next heating season.

I’d welcome any help that Aprilaire can lend in answering this reader’s
questions. Given that this is for the May issue, time is of the essence.

My answer:

Hi Roy, Happy to help.

It’s difficult to say all of the things to look for without knowing the model. For example, the damper "summer" setting would assume the reader has a bypass humidifier. If so, you are correct. And make sure to emphasize to change this every season so he is properly humidifying in winter, and not wasting air conditioning energy in summer.
But if it is a power unit, the model 700, there is no damper lever.
Besides that, however, you are correct. The water panel evaporator should be changed once a year; before the heating season.
 If there is white/gray "crust" on the panel that is crumbling, then it is probably deposit build-up and that’s the sign of a panel that needs to be replaced. Make sure he purchases Aprilaire brand. There are cheap knock-offs. He can buy them online or from his HVAC contractor.
Note, however, that a brand new water panel will come with the metal mesh already covered in a white slurry. This is sometimes confused with a panel that is dirty, but this is actually a slurry that is added in the manufacturing process to help the water cling to the panel and therefore aid in the evaporation process.
The reader should also make sure the drain lines are clear. If they’re not, they should be flushed or replaced. The water tube going from the water line into the humidifier should also be checked to be sure it is clear of deposits.
I would also instruct this reader that since he has purchased an existing home, he should have his heating and cooling professional check out his entire system, which he should do at least yearly anyway. At that time, the service tech can inspect the humidifier and make sure it’s all up to snuff. Likely, he can do all of the above maintenance I mentioned for a very small part of the service call.
This would also be a good time to see if there are any new upgrades that he might be interested in. For example, we’ve recently added automatic digital control to our units which are more accurate and eliminates the need for the homeowner to keep changing the humidistat setting based on changes in outdoor temperature.
If he needs to find an Aprilaire dealer near his location, he can go to  and type in his zip code in the FIND A DEALER box. He’ll also find alot of FAQ’s there and a 1-800 number where he can call in and get a live, Wisconsin body to answer his question!
Hope that helps.

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