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[Flyfishjt]

Searched and still can't find the answer. I have a propane forced air furnace with a/c unit. And having trouble finding what else I need to bring life to my owb. A freind of my has same set up and said I can just piggy back a seperate t-stat next to my existing one and run jumpers between the 2. So what's all the other things I've been reading about relays,aqua stats, Etc. ?  I know nothing about hvac. Oh and also I have a 4 wire running from my furnace to exsisting t-stat and no way of pulling a new/seperate wire from stat location to furnace cause of finished basement. Thanks in advanced.

[slimjim]

Single zone or multiple with zone dampers?

[RSI]

Try taking the wire off the G terminal and running it to the W on the new thermostat. You may need to splice a piece on so it is long enough to reach. Then add a jumper wire from the RH to the RH on the two thermostats. Also do the same if with the C to C terminals if there is a wire on the original thermostat. (the C isn't needed if your new thermostat uses batteries but connecting it may make the batteries only get used as backup power and won't go dead)

[Flyfishjt]

Got it! Thank you. After posting I did find a diagram on central boilers site. They did mention something about a relay when a/c is existing but couldn't I just remove a wire for the heating season and reattach during the cooling season so not to allow back feeding?

[RSI]

If you don't normally use the fan switch in the summer then just leave the wire off the G terminal and you don't need to put anything back in the summer.

[Flyfishjt]

Thank you RSI. I attached photo of my exsisting stat. I highlighted the terminals that are being used currently and also there is a jumper going from the R to RC terminals in place. My next question is if my stat doesn't have RH terminal do I just use the R? And if so do I leave factory installed jumper between the R and RC? Sorry if makes no sense I just don't want to fry my furnace and also don't want my A/C kicking on to fight boiler. Thanks again it's starting to make sense!

[Flyfishjt]

Forgot attachment

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[Flyfishjt]

Ok I just tried running a jumper from existing G to new stat W and R to R terminals and it kick my A/C on. Does it matter if I go from G terminal to W terminal or should I just take the wire completely off G terminal on existing stat and splice wires together.

[bajonesy77]

Take wire completely off of g and splice to w going to new stat. Here's a pic of mine, its a heat pump system. The blue wire nut is on the green wire that was on the g  terminal on the original stat and its connecting to the white wire that goes to the w on the new stat.

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[Flyfishjt]

Sweet I will give it another try tonight when I get home. I'm hoping that'll keep my a/c from kicking on. Thank you

[Flyfishjt]

Finally it worked!!!  That was the key was to do a direct splice and stay off the G terminal in existing t-stat. Still doesn't make sense in my head but don't care. The only thing I lose is the ability to run fan manually (who needs that anyway). Thanks guys

[RSI]

You can run the fan manually by just setting the temp higher on the OWB thermostat and just turning the switch to heat. Will do the same thing that the original fan switch used to.