HVAC Questions? Ask an HVAC Expert for Answers ASAP
There are 2 thermostats hooked up:
Blower only thermostat is a white-rodgers 1E78-140
Heat pump thermostat is a white-rodgers type-1F58-72
The furnace is a Comfortmaker and has 2 different model numbers on the same sticker ; NTG9125FKA3 and GNM125N20A3. The HP is a softsound 1200+ model CHP248AKA1.
Our fossil fuel kit number is XXXXX
YES, The hot water coil is on top of the furnace/cooling coil.
Alright since your HP stat is only a two stage we have this option. keep the set point of that thermostat 2 degrees lower than desired temperature. From the R terminal on the Furnace board run a thermostat wire from there to another thermostat you can use your 1 E78 if you like wire the R wire to R on that stat and from W on the stat run this to G on the furnace board. keep that thermostat at at you desired temp. With the 2 degree spread this should keep the furnace or heat pump from running and your wood furnace will heat the house. If it fails you have a 2 degree spread and the pump or furnace will come on. Return all of the wires from the Furnace and pump to their original position.
Another option is to purchase a three stage heat stat and we can combine everything to one control. Since these wood furnaces do vary let me ask you this, The water coil you have sits on top of the furnace make sure it is above the cooling coil and is it controlled by a valve ( electrically)? or just runs all the time? Secondly because you have this coil on there the furnace was not designed to run with that much resistance so you will have to check your air flow and blower speeds to make sure you get the CFM needed to cool or heat and protect the heat exchanger in the furnace. I hoped this helped. let me know if you have anymore questions.
This morning I wired the 2 thermostats as described above, but the outside unit still runs.
Alright, we have a different problem. If you take the wires off to the 1E78 blower fan. Does the HP still run? If so I need to know how you wired the Furnace /HP and FF kit. We probably have it mis wired., just tell me what color wires go to what terminals.
2 stage thermostat:
G-GREEN/BLACK (new one I ran to the new thermostat)
R-RED/BROWN(new one I ran to the new thermostat)
HP BOARD (on the outside unit)
When I removed the wires from the new thermostat, the HP kicked on.
It sounds like we have this mis wired. First lets get the HP and Furnace to operate correctly. Do you have a wiring diagram for your equipment? As I look at your last message you have W2 connected to the thermostat with a white wire that goes where? This is typically not used on a fossil fuel set up. I am searching for a diagram right now, I do have a diagram I can send you but your FF kit could be different.
Once we get the HP/Furnace operate correctly follow my last set of instructions to wire the blower for wood burner.
Let me know where that wire goes as I look up other information. Thank you
We do have a diagram for our FFkit.
It says the W2 from the 2 stage thermostat connects to the W on the thermostat side of the FF board.
Everything worked fine before we hooked up the wood stove. Today, after we unconnected the 2 wires on the new thermostat, our current still works same as always.
The wood stove works fine with our system, just the outside HP unit runs whenever the blower kicks on.
Alright, I have one more idea. On the 1E78-140 you used terminal R and W there was also a switch on the back for gas or electric. It needs to be put to electric, this will allow the blower to run on a call for heat. If the heat pump comes on anytime the blower is running there we have to have a back feed or a short. it is very difficult to do this without seeing it. As I look at the diagram anytime there is a call for fan the G terminal is powered on the FF board and the furnace. All other switching is controlled by the FF board. Which leads me to believe we have a failed board. let me know if this works if not i will opt out and see if someone else can get a better handle on it.
One more question, if you disconnect the Y off the thermostat will the heat pump still run? If it does the problem is most likely in the board if not the problem could be the thermostat. let me know I am very curious. Thank you
The IE78 does not have a switch on the back. (that I can find).
Also, when looking at the wiring diagram on this thermostat for heat only, it calls for a jumper wire from RC to RH that is not there. It is still in the box.
If you have the red wire on RH your OK, these are for separate heat and cool transformers and since your only heating with this stat you don't need to hook up the jumper but you can if you like. When i looked at the spec on the stat is showed a gas electric switch on the back. I might have been looking at an old spec and the unit was changed. If the fan comes on as soon as it calls for heat your OK. if it was set to gas the fan delays and waits for the furnace to call for fan.
Like I had said before this FF kit is solid stat ( board) so all functions are controls electronically. If that heat pump comes on when the fan calls i believe you have a failed board. The way to check, disconnect the Y wire off the stat if it still comes on it's in the board or the outdoor unit wiring, stuck contactor or board? We will have to further diagnose. let me know, Thank you for your patients.
I am assuming your outdoor temp is hi enough for the heat pump to call not the gas furnace? So we have proved the thermostat is making the outdoor unit come on.
Now after you hook everything back up and the fan only is calling check for voltage at the thermostat connection near the FF board, if you have 24 volts from Y to ground your thermostat has failed.
Are you sure when you had everything hooked up and the stat for the wood burner was calling that the other stat was set low enough not to call for heat?
I went back and hooked up the yellow wire on the 3 stage thermostat. I hooked up the other 2 wires on the thermostat like you said last night. The 2 stage thermostat was set on 70 and the new thermostat is on 76. When the blower first kicks on, so does the outside unit.
Our outside unit does not have a sensor. When the heat pump is on, it runs for so long. It will then kick to the gas furnance when needed. When it is too cold outside for the HP, we put the thermostat on AUX heat which is the gas furnance only.
I will get a tester tomorrow to test the 24 volts on the yellow wire.
If I get 24 volts on the yellow wire, the thermostat has failed. Should I get a three stage thermostat?
There should be a dial or setting on your FF board that you set the temperature to what you want the heat pump to stop and the gas furnace to come on. The best temperature to do this is about 40 degrees this was you have very few defrost cycles on the heat pump. If you get 24 volts on the stat when there is only a call for fan the thermostat is bad ,is this what you are reading?
Not being there it is very difficult to know exactly how this is working. I always hate to make someone spend money if they don't need to. However if you can't find someone that can accurately diagnose the problem a three stage thermostat with a fossil fuel kit built in would be the best way to do this. You would set the Wood burner to be the first stage of heat and just leave W open when it calls it will turn on the fan. Honeywell and White Rodger both make these stats. Again you might like a second opinion, but this is how I would do it.