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[bronco79]

I have searched n searched n can't find the same issue I have, so here goes... I'm ready to wire thermostat inside my house,i am going w a 2nd thermostat next to old stat. Research says... R- wire of old stat to r-wire of new stat , n then g-wire of old stat to w-wire of new stat. Using jumpers wies. I removed old stat n it runs off of 2 wires ... R-wire (red) and w-wire (white) and there were 3 others wires not being used. I went to the furnace n looked at circuit board n seen the other spots for wires , g being one of the spots where a wire can be connected. Would I hook up the g-wire at my furnace n run it to the w spot on my new stat?

[yoderheating]

 If its a basic heat pump jumper the r to r and the c to c. I use a Pro5000 Honeywell and I then run the w on the new to the g on the furnace and program the tstat accordingly. But I also run it through a relay so it can not back feed to the old tstat. Sometimes if it back feeds it will kick on your outside unit.

[Scott7m]

Hey bronco, my personal cell tower went down and I had no service at home. 

Hey.  Maybe someone else can way in on this as I've not seen any with only 2 wires.  It is my understanding that this is a gas furnace with no outside unit.  It's not something I ever see down this way

[RSI]

Sounds like an old heat only mechanical thermostat or originally was one.

Connect the 3 spare wires to the G, C and R at the furnace.
Then connect the furnace G to thermostat W, and the R to R and the C to C. The C wire isn't needed unless your thermostat needs power to run. If it uses batteries it won't need it but if you do connect it the batteries may only be used as backup power and not go dead.

[bronco79]

Ok thanks Scott it sounds like RSI is on to something that makes sense to me. Yea my set up is just a basement furnace n that's it . My thermostat is powered by batteries so sounds like I don't need c wire. I'll try that wiring set up today n let u guys know how it went. Thanks

[CountryBoyJohn]

I have a related question.  Can I go a "poor mans" route and simply unhook the "W" wire that turns on the heating element?  I don't have the funds for extra thermostats (I would need 2, one upstairs and 1 downstairs) but just want to do what is minimum to get the blower to run off the thermostat when it calls for heat.  Would that work?

[bronco79]

Also Scott, researching the stove settings , sounds like 170 w a 10 degree differnce is a good place to start ? Should I keep blower 100% open too?

[yoderheating]

 Wow, I can tell I was sleepy when I wrote that first comment. Didn't read the question well enough. So am I reading this correctly that your old tstat is only using the w and r terminals to run the current heating system? And I assume this is an electric or gas furnace? If its gas it may be using a heat sensor to turn on the fan which could cause an issue when you put in a coil. If you are running the pump 24/7 and the fan never shuts off you will have to install a low voltage 3 way valve.

[yoderheating]

Country Boy are you running a multi-zone heat pump system? Or is it a multi-zone gas or oil system without a heat pump?

[bronco79]

Yea its a propane furnace that's running off just the r-wire n w-wire on the thermostat. Should I try the hook like u explained earlier rsi ? Or u think I might have to do a switch

[yoderheating]

 If its just propane try it like RSI suggested. 9 out of 10 times its going to work well. You will know if you need a zone valve because the fan will not shut off. However if you put the coil in the return then you asking for trouble.

[bronco79]

No coil in the return . Yea I'm gonna give it a shot n see if fan will run off of 2nd stat . If not back to the drawing board. Everyone is very helpful on this forum , its awesome. Can't wait to start the fire !!!! No propane bill this winter

[yoderheating]

Thats the best part, watching the oil truck go by my house to the neighbors. He hasn't been to my place in 10 years! You should be fine, try not to install the coil right on top of the furnace as well. If you have some room in the plenum a foot or two from the furnace that would be great.

[CountryBoyJohn]

I'm all resistance electric.  No heat pump.  No gas.  No LP.  Ideally, I'd like to get a 2 source thermostat that has the 1st source as just the fan with no heating element, and the second source to be fan plus heating element.  For now, I'm hoping that un-hooking the "W" wire will give me the fan only, when the stat calls for "heat."

[yoderheating]

 Without looking at it I couldn't be 100% sure but it sounds like it should work just fine so long as your existing tstat is activating the g terminal as well.