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[WoodMOJoe]

I know this has been discussed here before but my searching brought up nothing that made sense for my specific situation, so...

My system...propane upflow furnace w/AC, homemade outdoor boiler (online soon I hope!).

I am wanting to use a second thermostat to control the blower when the OWB is producing heat, and my existing thermostat to fire up the propane unit if the OWB fails to hold the heat up.   I was planning on using a cheap programmable t-stat (probably a Honeywell) for the 2nd t-stat, but would be glad to hear any recommendations.

***Here are pics of my existing wiring at the back of the t-stat and where that wiring connects to the propane furnace.  I guess the extra red and white wire at the furnace go out to the A/C compressor.***  Let me know if you need any more info, thanks.

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[RSI]

All you should have to do is remove the wire from the G terminal on your thermostat and run it to the W on the new thermostat. Then put a jumper wire from the RH on the original thermostat to the RH on the new thermostat. If you have a wire on the C terminal, you can also run a jumper to the C on the new thermostat.

The C connection is needed if your thermostat doesn't use batteries. If it does use batteries and you connect the C it most likely will only use them as backup so they won't go dead.

[WoodMOJoe]

Thanks RSI.  I had found a post of yours that was similar to what you just said here but the other poster had introduced wire colors into the mix and they just confused me (don't take much to confuse me  ).

I do have a wire on the C terminal at the furnace (think it's one of the ones going out to the A/C compressor), so if it won't hurt anything I will go ahead and run a jumper from C old to C new on the stats.  Both of my thermostats will have batteries in them.

[RSI]

C is a direct connection to the transformer. The A/C compressor may use it too.
The wire that controls the A/C compressor from your thermostat is the Y connection.

[WoodMOJoe]

C is a direct connection to the transformer. The A/C compressor may use it too.
The wire that controls the A/C compressor from your thermostat is the Y connection.

Got it, thanks.  Looking forward to getting things all hooked up and the first fire.  Looks like we should have some decent weather to work on it soon.

[WoodMOJoe]

Looking ahead (aka dreaming) to cooling season and was wondering...

Can I just turn the new thermostat to Off and operate my cooling system with my old thermostat...or do I need to return the wiring to the original setup...or...?

[RSI]

Yes, it should work fine.
If you want to run fan only in the summer, just turn the 2nd thermostat up and then the auto/off (on 2nd tstat) will do the same thing the fan switch used to before you moved the wires.

[WoodMOJoe]

Perfect, thanks for the info RSI.   

[sizmo]

I know this has been discussed here before but my searching brought up nothing that made sense for my specific situation, so...

My system...propane upflow furnace w/AC, homemade outdoor boiler (online soon I hope!).

I am wanting to use a second thermostat to control the blower when the OWB is producing heat, and my existing thermostat to fire up the propane unit if the OWB fails to hold the heat up.   I was planning on using a cheap programmable t-stat (probably a Honeywell) for the 2nd t-stat, but would be glad to hear any recommendations.

***Here are pics of my existing wiring at the back of the t-stat and where that wiring connects to the propane furnace.  I guess the extra red and white wire at the furnace go out to the A/C compressor.***  Let me know if you need any more info, thanks.

***The upload folder is full. Please try a smaller file and/or contact an administrator.***

Can't get the 2-75K pics to post, keep getting this message:

The upload folder is full. Please try a smaller file and/or contact an administrator.

WoodMOJoe:

I have the same furnace/AC/Wood boiler setup as you do. Another option is to use one thermostat for everything. I bought a touchscreen LUX thermostat. It will support two stages of heat. Your green wire for the fan only goes to the first stage of heat (wood boiler) the propane burner wire goes to the second stage of heat. You can then set the differencial on the thermostat. So when the wood furnace isn't heating enough, it will kick on the propane burner to bring the heat to where you have it set. Was real easy to do.

Let me know if you have any questions.

[WoodMOJoe]

Thanks for that info sizmo. 

I already have the 2-stat setup installed, but if one of them shoots craps in the future I would consider going with a single-stat setup.

[WoodMOJoe]

Last night I went to redo the new thermostat wiring (to change it from surface-mounted to hidden in the wall) and after re-reading RSI's great instructions I noticed something I missed the first attempt.

My new thermosat does not have a "RH" terminal, just "R" and "RC".  It also has a (removable) factory installed metal jumper from R to RC.

What terminal on the new stat can I use and do I need that jumper in place?  Or, do I need to get a stat with an "RH" terminal?

[RSI]

R is the same as RH. Some just label them different.
RH is for heat and RC is for cooling. You only take the jumper out if the heating and cooling systems are completely separate.

[WoodMOJoe]

Good deal, that is the way I had it hooked up before attempting the redo.   One of these days    I will get some water in the system and try it out, think I am ready now.

Appreciate all the help RSI.  If you ever need any tips on putting up a satellite dish system I'm your guy.   

[Farmer616]

im trying to do this exact same thing ive run the G from the old thermostat over to the W on my new one and ran a jumper from RH to RH, now my old thermostat is ran on batteries and my new one is not but neither of them have a C terminal, any help?? been fighting this for a while

[WoodMOJoe]

I have been burning for a couple of days now but am unable to get my "2nd" thermostat to control the system.

It's always worked before and I don't think I have changed anything.

It won't even run the furnace fan when you switch the fan to On position.

We have just been manually turning the fan on and off with the switch on the "1st" thermostat.

Have checked the wiring, even bought a new "2nd" thermostat and replaced it...no dice.

Hoping it's something simple I am overlooking but was wondering if anyone had any troubleshooting suggestions?