# Powering a 24v/millivolt thermostat to control a gas stove ?



## Laketahoedan (Feb 16, 2008)

I want to use an InTouch CA8900 thermostat to control a gas stove/fireplace. The CA8900 says (if you look at the InTouch website) it works for millivolt systems.

But to power the thermostat I need a "C" wire or 24v common, which the Jotul400 stove I want to control does not have.

So I was thinking of powering the thermostat with a 24v transformer which i think would require running a wire from it to the "C" terminal and one to the "RH" terminal.

Can I do this if the stove is hooked up to the "W" and the "RH" terminals? or would the 24v power back to the stove and damage it through the "RH" terminal.

thanks for any input.


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## griz (Nov 26, 2009)

Be careful of voiding the Jotul warranty & UL listing.

You may have some liability exposure by altering how the unit is intended to function.


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## flashheatingand (May 3, 2008)

I clicked on the link for the t-stat in question, but got a video version. Didn't get into installer section, so this comment is based on most 24v t-stats. The answer is no, but, you could use a battery powered stat.

As for that stat, I would call the manufacturer. I see it's a wireless stat, so, where would you put the receiver? There may be heat issues if you put it in the space below the fp. Also, I would call the manufacturer, and ask if the r,w,y,g contacts are dry contacts or not. If they were dry contacts, and you can find a suitable place to put the receiver, you should be good. After all is said and done, you may be better served, by running some bell wire, and installing a battery powered or standard millivolt stat.

Good luck


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## DuMass (Feb 6, 2008)

Are you using that particular t-stat because of the network control feature?
The manufacturer says it’s compatible with MV valves, so I would think that as long as you only connect W from the t-stat to TH on the valve and don’t also connect C from the transformer to TH/TP, it should be okay…. but if you want to be extra cautious, as I likely would, you could install a 24V cube relay and connect the t-stat wiring to control it, then make the connections to TH and TH/TP on the gas valve through a set of N/O contacts on the relay.


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## Laketahoedan (Feb 16, 2008)

DuMass said:


> Are you using that particular t-stat because of the network control feature?
> The manufacturer says it’s compatible with MV valves, so I would think that as long as you only connect W from the t-stat to TH on the valve and don’t also connect C from the transformer to TH/TP, it should be okay…. but if you want to be extra cautious, as I likely would, you could install a 24V cube relay and connect the t-stat wiring to control it, then make the connections to TH and TH/TP on the gas valve through a set of N/O contacts on the relay.


Yes, I am using it on the zwave home automation system.


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## Laketahoedan (Feb 16, 2008)

I finally got an answer from an engineer at WayneDalton who bought the Intermatic CA8900.

She said that the 24volt transformer wire to the RH terminal would not effect the RH wire back to the gas stove. hope she is right


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## flashheatingand (May 3, 2008)

That would mean you have dry contacts at the terminal in question, which is a good thing. But, to be sure, I would get my multi meter,set it to volts, and check the voltage between rh & c. If zero volts, set the meter to ohms (omega), and check the reading between rh and w. If the reading is something in the range of .1-.4, I would be confident that all is well.


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## Laketahoedan (Feb 16, 2008)

flashheatingand said:


> That would mean you have dry contacts at the terminal in question, which is a good thing. But, to be sure, I would get my multi meter,set it to volts, and check the voltage between rh & c. If zero volts, set the meter to ohms (omega), and check the reading between rh and w. If the reading is something in the range of .1-.4, I would be confident that all is well.


sweet, thanks for that info.


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