Try to get older system to work with Honeywell RTH9580
#1
Member
Thread Starter
Try to get older system to work with Honeywell RTH9580
Hi, newbie here...
I'm trying to get a Honeywell RTH9580 to work with my hot water baseboard heat and forced air AC. The AC unit is pretty old but it does have the capacity to power the thermostat. My problem is that I cannot reconcile the available wiring on the AC panel to what I need on the Honeywell. I can't find anything on-line either to sort it out. I can get the heat side working fine,
The AC panel has the following terminals: C G W1 W2 W3 R. Its a single stage unit. Any ideas on how to translate this to a (more) modern wiring nomenclature? I need to wire it an way so it also powers the thermostat as well.
Thanks in advance!
I'm trying to get a Honeywell RTH9580 to work with my hot water baseboard heat and forced air AC. The AC unit is pretty old but it does have the capacity to power the thermostat. My problem is that I cannot reconcile the available wiring on the AC panel to what I need on the Honeywell. I can't find anything on-line either to sort it out. I can get the heat side working fine,
The AC panel has the following terminals: C G W1 W2 W3 R. Its a single stage unit. Any ideas on how to translate this to a (more) modern wiring nomenclature? I need to wire it an way so it also powers the thermostat as well.
Thanks in advance!
#2
Member
Thread Starter
Pic of current A/C connections.....
Last edited by PJmax; 05-17-19 at 04:41 PM. Reason: cropped/resized/labeled picture
#3
Welcome to the forums.
At the thermostat....... pull off the R to Rc jumper.
Red from A/C needs to be on Rc at stat.
Green from A/C needs to be on G at stat.
Blue from A/C needs to be on Y at stat.
White from the A/c needs to be on C at stat.
Connect the white wire in the thermostat cable to C on the furnace with the red wire from the A/C condenser.
The heat connects to R and W-O/B. No polarity.
At the thermostat....... pull off the R to Rc jumper.
Red from A/C needs to be on Rc at stat.
Green from A/C needs to be on G at stat.
Blue from A/C needs to be on Y at stat.
White from the A/c needs to be on C at stat.
Connect the white wire in the thermostat cable to C on the furnace with the red wire from the A/C condenser.
The heat connects to R and W-O/B. No polarity.
#4
Member
Thread Starter
Thanks a bunch Pete - I'm going to give it a try. Just not 100% sure what you mean when you say:
"Connect the white wire in the thermostat cable to C on the furnace with the red wire from the A/C condenser."
"Connect the white wire in the thermostat cable to C on the furnace with the red wire from the A/C condenser."
#5
Look at the picture. Look at the cable that goes to the thermostat.
White is not connected. It needs to be.
White is not connected. It needs to be.
#6
Member
Thread Starter
Oh OK, you said "for the furnace" - you mean connect the white wire to the C terminal on the AC as in the pic. Sorry, just trying to make sure I do this right. Thanks again.
madski
voted this post useful.