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Eric I am not sure you can use the Nest with a zone system, Do you want to try to see if we can find the fuse so you can reconnect old thermosat? If so give me model on your air handler/furnace.
OK, The only problem people usually run into trying to use the Nest with a zoned system is that often zone dampers are controlled by transformers independent of the furnace transformer.In that case you are sending power from the furnace transformer on one wire and common to zone damper from a different transformer.
What is model on furnace or air handler that thermostat controls?
Remove front panel on furnace and look inside for a control board and see if there is a small automotive fuse on board
Probably in lower panel
Check this fuse.See if blown
That does not look blown. Put it back. Next tell me where that board zone is getting low voltage to these terminals.
I did not ay fuse WAS definitely blown,I said it may be and we should start there. I do not think this fuse is the issue. Do you have a volt meter to see if that little plug in transformer is sending 24v to zone board?
Do you have anything else that operates on 24 volts? You can plug something into plug to make sure plug is working but that will not tell us if you fried the little plug in transformer
Check between those two terminals for voltage
Yes on those two wires we should get 24 volts
Leave wires connected
You should be getting 24 volts there,If not you probably fried that little plug in transformer. When connecting the nest did you allow wires to touch while they were disconnected?
The little transformer that supplies power to zone panel is what I am referring to.Did you have power off to it when changing thermostat?
You have just tested it, You determined that the plug is hot by plugging something else in.You determined it is not sending 24v out to board with meter. Home depot may have these as they are pretty common transformers.
It is possible, but lets hope not
Lets wait until we get finished.Tomorrow is fine.
Talk to you then.