Furnace / Heat Pump Wiring
#1
02-07-18, 12:37 PM
Furnace / Heat Pump Wiring
The control board on my Lennox G26Q3-75-4 gas furnace went out. I ordered a new control board and installed it. Only misstep was the very last thing I did. When I went to transfer the thermostat wires and two wires from the heat pump (Trane XE 1200, model number TWP036C100A1), I didn't take proper notes. I attached the wires incorrectly and the furnace wouldn't turn on. I disconnected the wires coming from the heat pump and now the furnace turns on and runs correctly.
Wanting to get the heat pump connected correctly before summer gets here.
On the furnace control board, there are five thermostat connections - Y, W, R, G, and C. From my thermostat/humidifier/controller I have the yellow wire connected to Y, the white wire connected to W, red wire connected to R, green wire connected to G, and a brown wire and blue wire both connected to C.
There were only two wires coming in from the heat pump that were connecting to the furnace control board with the thermostat wires - a white wire and a red wire.
Can anyone help me figure out which terminals the white and red wire from the heat pump should be connected to?
Thank you!
Wanting to get the heat pump connected correctly before summer gets here.
On the furnace control board, there are five thermostat connections - Y, W, R, G, and C. From my thermostat/humidifier/controller I have the yellow wire connected to Y, the white wire connected to W, red wire connected to R, green wire connected to G, and a brown wire and blue wire both connected to C.
There were only two wires coming in from the heat pump that were connecting to the furnace control board with the thermostat wires - a white wire and a red wire.
Can anyone help me figure out which terminals the white and red wire from the heat pump should be connected to?
Thank you!
#2
02-07-18, 01:48 PM
With only 2 wires go outsi9de it's not a heat pump. The red wire will be on Y and white wire goes to C.
#3
02-07-18, 05:53 PM
Group Moderator
Welcome to the forums.
That model is a Trane heat pump.
He mentioned only two of the wires from the heat pump connected to the furnace board....... but there should be more than two to the furnace board.
There should be an R wire, a Y wire, a C wire and possibly a W wire based on using the furnace for AUX heat while defrosting,
That model is a Trane heat pump.
He mentioned only two of the wires from the heat pump connected to the furnace board....... but there should be more than two to the furnace board.
There should be an R wire, a Y wire, a C wire and possibly a W wire based on using the furnace for AUX heat while defrosting,
#4
02-07-18, 06:47 PM
skaggsje, thanks for your response. Perhaps I should clarify, there are more than two wires coming in from the heat pump but only two of those wires were connected to furnace control board. I didn't originally install the heat pump or the furnace so I'm not sure why only two of the several wires coming in from the heat pump were connected to the control board. Could it have been setup like this to only use the air conditioning function of the heat pump and not the heating function?
Thanks for your help!
Thanks for your help!
#6
02-07-18, 09:27 PM
Most likely either the brown or blue wire goes to the O/B terminal on the thermostat and should not be connected to the furnace but spliced to the heat pump. Take a look at the thermostat to see what color wire is connected to which terminal.
#7
02-25-18, 10:35 AM
Pics attached
Everyone, attached are pictures of the control board, wires from the heat pump at the control board, and wires at the heat pump. I have also documented on the pictures what colors the wires are. In case you can't see on the picture and to recap:
- My heat (furnace and blower) are working and a picture of the wiring on the control board is attached. There were two wires from the heat pump that were attached to the original control board but I failed to note where they were connected. There are other wires coming in from the heat pump but they were not attached to the control board.
- The two wires at the control board (from the heat pump) that I need to re-attach are the red and white wires.
Thanks for your help and sorry for the late reply, I have been out of town.
- My heat (furnace and blower) are working and a picture of the wiring on the control board is attached. There were two wires from the heat pump that were attached to the original control board but I failed to note where they were connected. There are other wires coming in from the heat pump but they were not attached to the control board.
- The two wires at the control board (from the heat pump) that I need to re-attach are the red and white wires.
Thanks for your help and sorry for the late reply, I have been out of town.
#8
02-25-18, 11:00 AM
Group Moderator
What makes this difficult is we aren't seeing all the wiring.
We see 6 wires at the furnace but this cable is not from the thermostat as there is no orange wire for the heat pump. You are showing us two wires from the heat pump that connect to the furnace.... where are the other wires since there are at least 4 connected outside ?
Is there one cable or two outside at the unit ? I can't clearly see the wiring.
I'd say there is a splice somewhere that we aren't seeing.
We see 6 wires at the furnace but this cable is not from the thermostat as there is no orange wire for the heat pump. You are showing us two wires from the heat pump that connect to the furnace.... where are the other wires since there are at least 4 connected outside ?
Is there one cable or two outside at the unit ? I can't clearly see the wiring.
I'd say there is a splice somewhere that we aren't seeing.
