I am installing a new thermostat that has built-in humidity control to get the ugly humidistat off my living room wall. My problem is that the thermostat is stealing 24v power from the RH to power the H wire that leads to the humidifier. I say that this is a problem, because the book on my furnace specifically states not to run a humidifier from the transformer on the furnace.

I do have a 110 HUM lead on the furnace and a 24v transformer that has been running my humidifier. I'm just not sure how to wire the new thermostat into the mix.

Also, wouldn't wiring the humidifier to this thermostat this way cause it to open the water valve even if the blower isn't running?


Here is my thermostat: http://www.ntsupply.com/files/products/43885.pdf

Thermostat: CTC Programmable Touchscreen Thermostat with Humidification Control
Model: 43855

Humidifier: Bestair Humidifier
Model: BA3200G

Furnace: York
Model: P4HUC16N09201B

 

The H is going to get the power from the t-stat. Honestly, Hunter makes great fan, but not t-stat.

If you want a good t-stat, I'd suggest Honeywell IAQ. They use a "switch" for humidifier hook up, so you are not "stealing" power.

By the way P4HUC16N09201B is the coil above the furnace.

 

The Honeywell does look nice, but the price is $100 more!

Is there anyway to get the one I have to do what I want? Right now I have it wired to "steal" the 24v it needs to run the humidifier.

Besides the fact that it's taxing the transformer on the furnace it runs the humidifier and doesn't kick on the fan when the thermostat senses the need for more humidity.

I can't imagine this product was that poorly designed!

 

Honestly, If you want to keep that t-stat, I'd go ahead and wire it to the humidifier.

That coil on the humidifier is not taking anymore power than the coil on the A/C unit outside in the summer when it's running.

Other brand that has 24 volts on the board use the same transformer.

Let me know if you want to give it a try. The worst thing can happen is the burner won't light, and then we will have to look at another plan.

Oh what's the model # on the furnace, not A Coil.

 

Thanks for the reply!

I went ahead and wired it in to the thermostat and it works fine.

However.....

When the thermostat calls for humidity it does not turn on the blower, therefore dumping water down the drain....

If the thermostat calls for heat and humidity the system works fine.

I've had to leave the blower in the 'on' position so that at least the humidifier is doing something rather than just wasting water.

The Model number I gave was the number listed inside the furnace door. I'll have to check for a different one when I get home from work.

 

That's what I don't like about Hunter... HOneywell won't turn on the humidifier till either the fan is on, heat, or force the fan on.

The model # is in the burner area of the furnace.

 

Front of furnace



A Coil Front



Inside of furnace door



Front of burner

 

Ok, you are correct on the model #. I went bck to my search, and I didn't read it close, jut was a cross ref of a coil that could work with your furnace.

You have a single stage furnace, so the IAQ can be an over kill for you.

 

So what thermostat would you suggest that will also run the humidifier?

I'd like a programmable thermostat and has a N/O contact for the humidifier. The IAQ would do the trick, but it's almost like having a supercomputer running a VW Bug.

 

Honeywell IAQ is the only one I'm aware of. The other thing we can do is add a A50 relay to your Hunter, that way the humidifier will only run when the fan is running.

 

I wondered if a current sensing device existed! That would work good. However, I've now discovered that this Hunter thermostat will only allow the cooling program to turn down to 71F. I'm not happy about that restriction, so I'll be returning this thermostat and buying the IAQ.

Thanks again for all of your help. Hopefully this thread will help someone else.

 

Let me know when you do get the IAQ, and I'll get you all set up with it.