When should my Aprilaire model 700 humidifier run?

Consumer question:
Since my model 700 was installed last winter, I've noticed it sometimes runs even if the heater isn't running. Also, sometimes, if the heater is running, the humidifier does not. It seems to run completely independently of whether the heater is running or not. Is this normal?
Aprilaires' response:
Thank you for contacting us. The humidifier does not regularly run independent of the furnace when wired to turn on and off with the furnace heat call. If you turned the humidistat down when the humidifier was running, does the humidifier turn off? If the humidifier stays on when the humidistat is turned down, then you would have a bad solenoid. If the humidifier turns off then you have a good humidistat and good solenoid.

Do you have a digital humidistat that you are controlling the humidifier with? The digital humidistat has a blower activation switch on it and you might have that in the on position. Turning the blower activation switch to the off position should solve your problem of the humidifier running in these different times.

If you have a manual control to wired to the humidifier, then you would need to have your service contractor trouble shoot the current sensing relay that would be wired between the humidistat and humidifier.
If you have any other questions please contact us at 800-334-6011. Thank you


2 thoughts on “When should my Aprilaire model 700 humidifier run?

  1. Keith

    I have an Aprilaire 7000 which had not worked since last year. I had replaced the solenoid and replaced the “filter” when I powered it back on it started to work. Our home had a lot of static before. this. I set it at 35% but now it will not sure off unless I turn it to off on the manual setting? Since it had not run for some time would it just be getting acclimatized to the home?

    The furnace is not on and it still continues to run. I now have it in the off position, but I did notice the solenoid is very hot to the touch?

    I just had the HVAC rep here two weeks ago and they never checked the humidifier even though they were the ones who installed the unit.

    Suggestions, thoughts

    1. aprilaireadmin

      Dear Keith,

      Thank you for your inquiry regarding the operation of your Aprilaire Model 700 Humidifier. All Aprilaire humidifiers are designed to maintain an indoor humidity level of 35% at a room temperature of 70 °F any time the outdoor temperature of 20°F or above. Since the humidifier was off, it will take time for humidity to build back up in your home. You indicated the humidifier runs without the HVAC operating. Since the humidifier should only operate when the HVAC is on, it appears it is not wired correctly. You will please want to contact your HVAC installer so they can wire the humidifier to only operate when the HVAC system is on. It is typical for the solenoid to be warm to the touch when operating.


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