Need C-wire for new Honeywell RTH6500WF Thermostat

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Need C-wire for new Honeywell RTH6500WF Thermostat
Posted On: May 14, 2024

I am upgrading my old non-wifi programmable thermostats with Honeywell wifi models. These need a C-wire and my wiring only has 4 conductors and no C-wire. I contacted Honeywell support and they suggest using a C-wire adapter, but it appears my system's air handler units for heating/cooling do not have a control board with a terminal block to connect the adapter to. I opened the side panel. They are First Co units that were installed when the house was built 30 years ago. There's a unit in my basement, and one in the attic. All the wiring connections are mounted on the outside of the units. Only 3 wires go into the unit beside a separate AC power line. Can I still use a C-Wire adapter with this configuration? What are my options to provide a C-Wire to my new thermostats?


Question from user NetGeni59 at stackexchange.


Answer:

If you can, run the Brown wire coming from the transformer to the thermostat. That would be your C wire.


Answer from user Traveler at stackexchange.



[BACK]
Need C-wire for new Honeywell RTH6500WF Thermostat
Posted On: May 14, 2024

I am upgrading my old non-wifi programmable thermostats with Honeywell wifi models. These need a C-wire and my wiring only has 4 conductors and no C-wire. I contacted Honeywell support and they suggest using a C-wire adapter, but it appears my system's air handler units for heating/cooling do not have a control board with a terminal block to connect the adapter to. I opened the side panel. They are First Co units that were installed when the house was built 30 years ago. There's a unit in my basement, and one in the attic. All the wiring connections are mounted on the outside of the units. Only 3 wires go into the unit beside a separate AC power line. Can I still use a C-Wire adapter with this configuration? What are my options to provide a C-Wire to my new thermostats?


Question from user NetGeni59 at stackexchange.


Answer:

If you can, run the Brown wire coming from the transformer to the thermostat. That would be your C wire.


Answer from user Traveler at stackexchange.



Need C-wire for new Honeywell RTH6500WF Thermostat

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