Try to get older system to work with Honeywell RTH9580

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Old 05-17-19, 03:56 PM
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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!
 
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Old 05-17-19, 04:00 PM
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Pic of current A/C connections.....

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Last edited by PJmax; 05-17-19 at 04:41 PM. Reason: cropped/resized/labeled picture
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Old 05-17-19, 04:51 PM
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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.
 
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Old 05-18-19, 10:40 AM
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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."
 
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Old 05-18-19, 10:58 AM
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Look at the picture. Look at the cable that goes to the thermostat.
White is not connected. It needs to be.
 
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Old 05-18-19, 12:55 PM
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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.
 
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Old 05-18-19, 07:37 PM
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Got it working - thanks Pete!
 
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Old 05-18-19, 09:21 PM
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Good job. Thanks for letting us know how you made out.
 
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