Humidifier won't turn on with furnace fan set to Auto.
I live in western NY and we've had the furnace on for weeks now. Lately, highs are near 30 degrees and lows around 20.
My (Trane) thermostat has two fan settings - Auto and On. In On mode, the fan runs 24/7 at very low speed. In the winter, with the heat on, I prefer Auto mode which is where I have the Thermostat set.
I had a feeling my new Aprilaire 600 wasn't working since the RH was slowly dropping (over a few days) down to 30%. I was looking for 40% so I had been slowly moving the adjustment dial up to 7 with no corresponding increase in RH.
I also noticed that when the heat kicked on, nothing happened at the humidifier control panel - i.e. no green light, no water. However, the humidifier did work properly in Test mode.
So I checked around the Internet and found a post that suggested switching the Thermostat fan setting from Auto to On. Bingo! The next time the furnace kicked on the green light on the humidifier panel came on and the water flowed. It now continues to work "properly."
The bad news, as I mentioned above, is that I prefer to have the Thermostat (fan) setting on Auto, not On. So my questions:
1) Is this normal? 2) If not, which device is probably at fault? 3) Can the thermostat and/or the humidifier control panel be rewired by my service rep to "fix" this?
Re: Humidifier won't turn on with furnace fan set to...
There is a devise called a current sensing relay (a little black box that hangs on a blower motor wire that senses current from that wire) If you have such a devise it should hang from the white (common) wire. Loop the wire through twice.
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first , make sure thermostat is level on the wall. If o.k. try adjusting the anticipator at the thermostat. remove cover and you should see same as in picture. Move arm away from longer slightly, and try it a few times, each time before going more. If that doesn't help, it may be time for a new thermostat.
Is the furnace fan set on auto or on. You will get better humidity if you keep the fan on. It won't add much to your electric bill because many of the newer furnaces operate the fan on DC voltage. Try it!
A simple check you can perform on your aprilaire 760 is the following:
1) locate the two brown wires coming out of the 760 (these wires will be wired to tell the 760 to turn on when the hvac bower is on and the humidistat is calling for moisture).
2) temprarily disconnect the two brown wires from the external wiring and then short the wires together. All you're doing here is bypassing the your thermostat and bower-on indicator.
With the 70 unit plugged in to the wall outlet and the two brown wires connected together, both the fan and the solenoid valve (water inlet valve) should both be activated.
It is possible that you did not set the new blower on the proper speed. Black wire is high. Blue is medium. Red is low. If the fan is operating to slow it can run to hot and trip the high limit control. Make sure the filters are clean. When the old motor went bad, the problem might not have been discovered rite away your high limit control might need to be changed.
Also anytime you work on a furnace you can kick up some dust. Always clean the flame sensor.
You should take out that aprilaire and throw it in the garbage or return it to who you got it from. Ask them why they didn't offer you the best humidifiers available. The only way to truly control humidity in your home without running your heat is a steam humidifier. Autoflo makes a good one also honeywell makes a new one. I have installed a honeywell tru steam in my own home and a few customers it hasn't lived up to its advertising. The auto flo has never given me any problems with customers.
I am not a furnace guy but I may be able to give you a few ideas of things to diagnose the problem and get it resolved. First off, I assume you have a thermostat that you use to to turn your heat on. If it is a generic ( meaning : non programmable model) then you should be able to try this simple test. Remove the cover ( typically they snap on) around the thermostat so you can see the control mechanism inside. You should see few skinny wires ( similar to those used on a telephone wire) solid copper in various colors.. When you rotate the dial on your thermostat to call for heat, there is a small glass vial that has a drop of mercury ( which is electrically conductive) in it that makes contact and shorts two control wires together ad that is what calls for heat on your furnace. When the temp inside the room where the thermostat is reaches the tempertaure you requested, the bimetal mechanism either contracts or expands to reposition that glass vial to shift the mercury off the contacts and your furnace shuts off... That is the basics behind how your thermostat and furnace work ( generally speaking) If you can identify the two wires inside the thermosat that are shorted together when that vial of mercury shorts them inside it.. you can temproarily unhook them ( they are low voltage.. normally 24 Volts or less) so no worries about getting ashock or anything.. and short them together for a minute or two.. by doing that... your furnace should turn on and heat should flow.... Once you start your furnace this way.. unhook these two wires and your furnace should shut down .. It may take a minute or two ( depending on the control for it) If it doesn't..then your problem is on the furnace side and you may need to get the furnace control system serviced or replaced.. if it does shut down, then your problem is your thermostat and thats a simple replacement.. Also.. make sure the thermostat was properly leveled on its base.. The position of the thermostat ( meaning level) will dictate when that mercury makes contact and your furnace switches on.. OK..I tried to explain the works of this to you but here is a link to a Honeywell site that explains it in simpler terms.. The part about shorting the two wires together and then opening them will aid you in identifying where the problem actually is.. here is the link: http://homerepair.about.com/od/heatingcoolingrepair/ss/thermostat.htm
Hope this helps you more than confuses you..