Why do I hear some people say not to trust a humidistat?

unless the humidty in your home is higher then 35%. if it is then the humidifier would not run. try turning it up higher and see if it comes on. Do you hear a click in the humidistat? as you turn up the dail when you hear the click is when the humidifier should come on. Also remember your furnace must be running for the humidifier to come on. if you hear the click and the humidifier fan comes on but no water, you may have a clogged inline filter located in the solinoid valve or a bad soliniod. all parts for your humifier can be purchased from www.aprilaire.com

Turn off the water to the humidifier

Disconnect the water line to the inlet water valve (the solenoid), catch any excess water or drips in a small container

Turn the water back on slowly and see if water flows through the open line (the one you just disconnected - catch the water in a small bucket)

If you have water to the valve, it's probably the solenoid valve - you can test this by reconnecting the water line and turning the humidistat all the way up. You should hear a click as the solenoid tries to open. If it clicks and no water comes out it's the valve. If there is no water to the valve, you'll need to determine the reason(s). Although not every water valve has one, check for a plugged inlet screen at the entry to the water valve (solenoid)
Sometimes the small line tap valves commonly used with humidifiers can plug up or malfunction. If you try to repair or replace the tap valve, make sure the water is turned off.
If no click, it could be the humidistat or there is no power to the unit.
If the humidistat is bad, you won't hear any click and no power will be sent to the solenoid valve. In that case, the humidistat may be defective.

Depending on your comfort level and knowledge, you can try applying power directly to the valve by bypassing the humidistat, but only try this if you are comfortable working with electricity. The voltage should be around 24 volts (in the USA) , which is low, but requires some knowledge.

Turn off the water to the humidifier

Disconnect the water line to the inlet water valve (the solenoid), catch any excess water or drips in a small container

Turn the water back on slowly and see if water flows through the open line (the one you just disconnected - catch the water in a small bucket)

If you have water to the valve, it's probably the solenoid valve - you can test this by reconnecting the water line and turning the humidistat all the way up. You should hear a click as the solenoid tries to open. If it clicks and no water comes out it's the valve. If there is no water to the valve, you'll need to detrmine the reason(s). Sometimes the small line tap valves commonly used with humidifiers can plug up or malfunction. If you try to repair or replace the tap valve, make sure the water is turned off.

If no click, it could be the humidistat or there is no power to the unit.
If the humidistat is bad, you won't hear any click and no power will be sent to the solenoid valve. In that case, the humidistat may be defective.

Depending on your comfort level and knowledge, you can try applying power directly to the valve by bypassing the humidistat, but only try this if you are comfortable working with electricity. The voltage should be around 24 volts (in the USA) , which is low, but requires some knowledge.

reason why I asked they sometimes have a problem sensing current and you may need to wind the wire twice instead of one pass. If you jump the wires at the humidistat and the unit turns on its either the stat or you may want to do a relative humidity check on the house to see where your at

Best regards,
Tinner

you can bypass the humidistat by shorting the 2 brown wires on the bottom of the humidifier. just remove the 2 wire nuts and touch the 2 together (just 24v)if it comes on then there is a control problem with the humidistat or wiring if it doesnt come on the control board or transformer may be bad or you dont have 120v to the humidifier on the plug. also make sure your furnace blower is running cause the hum cant come on if its wired properly unless the fan is running. you also may want to go to www.aprilaire.com and get a maintenace kit from their online store. it comes with pad and new hose along with a couple other things.

In order of probability:
1) (incorrect wiring) Make sure that humidistat is in SERIES wired with the furnace.
2) (shorted wires) Check that two wires to humidistat are not touching...use your glasses if you need them!
3) (bad humidistat) disconnect the humidistat and put an ohmmeter accoss the two terminals when it is turned on you should read 0 ohms, and when off it should read infinate ohms, if not pass both these tests, you need new humidistat.
That is it, there are no other possibilites!

Given all other variables are the same (location, average humidity, humidistat setting, etc.) I would speculate either:

- the compressor is not running as much as before, or
- the evaporator is icing up and blocking ariflow, or
- the compressor is not getting evaporator coils cool enough, or
- the fan is not running at top speed.

Have you checked for icing?
Has the humidistat setting been inadvertently changed?
Does the fan seem to be operating normally?
Do you hear the compressor "kicking in", or is it just the fan you hear?

It sounds like the humidifier may be improperly wired.
It's hard to solve without checking the wiring, but it seems like the humidistat is wired so that as the dial is advanced, it incorrectly turns on the fan, or furnace, or both.  The contacts of the humidistat should be wired so that they turn on the solenoid only.  Also, the power to the humidistat, to turn on the solenoid, should come on only when the fan is on.
Hope this helps!

Hello All,

Was having a similar problem. Disconnected the source line and opened saddle valve. I was getting water to the solenoid but nothing out the other side. My humidistat doesn't have a "test" setting, it's either off or the highest humidity. I held the outbound line in my hand and experimented with adjusting both sadlle valve and humidistat. I didn't get any water until I opened the saddle valve MUCH further than I thought was necessary and turned the humidistat to near the highest setting. Once I had water coming though I experimented with the setting on the humidistat, turning it off and then slowly increasing the humidity until the solenoid clunked and water started coming out. I would recommend anyone having this same problem to open the saddle valve all the way (I was surprised how many turns that took) and set the humiditstat to it's highest setting.

Randall