Hi,

I have a 3rd party humidifier that I want controlled by my Ritetemp 8085C digital thermostat. However, I'm not sure how to wire it up. The humidifier just needs a simple open/close circuit switch for control. My thermostat provides this functionality.

I don't want to rip out drywall to add more wires :(

My current setup is this

Furnace -> colour <- Thermostat
R <- Red -> RC/RH (jumped so one wire is really redundant)
R <- Black -> RC/RH
Y <- orange -> Y
W <- white -> W
G <- green -> G

I know I can use either the Red or Black wire, since they are jumped at the thermostat and both lead to the same terminal "R" on the furnace, so one is redundant. Cool, half way there! :)

But...

I need to find a common path back to the humidifier through one of the other wires. Can any one of these others be shared with the humidifier (as a common to the humidifier), as not to interfere with the correct operation of the thermostat?

Any assistance would be most welcome.

The humidifier is normally controlled by a humidistat unless your thermostat has this capability, you could pick up a common wire in the furnace for the humidifier and only run one wire back from the thermostat or mount a humidistat next to the thermostat and run a wire from the "W" terminal to the humidistat and then to the humidifier through the black wire. Hope this is helpful, Mike

The humidifier is normally controlled by a humidistat unless your thermostat has this capability, you could pick up a common wire in the furnace for the humidifier and only run one wire back from the thermostat or mount a humidistat next to the thermostat and run a wire from the "W" terminal to the humidistat and then to the humidifier thru the black wire. Hope this is helpful, Mike

Hi, yes, my thermostat is also a humidistat.

Ritetemp 8085C (http://www.ritetemp-thermostats.com/8085C.html) It has the "H" connector.

My humidifier is just a 3rd party add on, it came with a humidistat, but my problem is, I burn wood in the winter, so the furnace does not kick in for heat, (not very often). So what would happen is the humidifier would start the water flowing, but the furnace would not know to start the fan.

I'm confident that my Ritetemp thermostat will engage (just) the fan when the humidity drops, and in turn close the circuit to the humidifier module, starting the water flowing over the filter.

After some research, I think I may be able to share the [edit] "W" as the return to close the humidifier circuit. But I need more info, I don't want to mess my furnace up :) Yeow.

Thanks for your answer.

Most humidifiers need to have the warm air coming off the furnace to pass through the humidifier and pick up moisture, with out this warm air the water will not evaporate from the humidifier, this is why the furnace needs to run.

Most humidifiers need to have the warm air coming off the furnace to pass thru the humidifier and pick up moisture, with out this warm air the water will not evaporate from the humidifier, this is why the furnace needs to run.


Right you are most humidifiers require that, however, mine does not. It's a high effecicency humidifer and will work with hot or just 'room temprature' air.

HOWEVER, I think I have found a solution, I need to do more reading, but this is what I have so far. It looks like what I want to do...

Page 19 of this document:
http://www.ritetemp-thermostats.com/images/ritetemp_Professionalreferenceguide_current.pdf

What type of humidifier do you have a lot of the newer ones have their own transformer and just need to compleat the circuit from W on the furnace through the humidistat and then to the humidifier. If It's a high efficicency humidifier it should be that simple.

What type of humidifier do you have a lot of the newer ones have their own transformer and just need to compleat the circuit from W on the furnace thru the humidistat and then to the humidifier. If Its a high efficicency humidifier it should be that simple.

Yes, that's what I was thinking myself. I was just looking for the other side of the "H" to close the circuit.

The humidifier does have it's own transformer.

It is a Honeywell HE260A (http://yourhome.honeywell.com/Consumer/Cultures/en-US/Products/Humidifiers/Humidifiers/Do-It-Yourself/Bypass+Flow-Through/Default.htm)

So, this sounds like good news. Using "H" & "W" I can complete the circuit to my humidifier, because it has its own transformer?