![hvac - How can I modify a 4 wire thermostat to a new thermostat requiring c wire? - Home Improvement Stack Exchange hvac - How can I modify a 4 wire thermostat to a new thermostat requiring c wire? - Home Improvement Stack Exchange](https://i.stack.imgur.com/iKWAum.jpg)
hvac - How can I modify a 4 wire thermostat to a new thermostat requiring c wire? - Home Improvement Stack Exchange
![Wiring New Honeywell RTH6580WF Thermostat with no Yellow Wire at Thermostat - Home Improvement Stack Exchange Wiring New Honeywell RTH6580WF Thermostat with no Yellow Wire at Thermostat - Home Improvement Stack Exchange](https://i.stack.imgur.com/JTyJM.jpg)
Wiring New Honeywell RTH6580WF Thermostat with no Yellow Wire at Thermostat - Home Improvement Stack Exchange
![Blue "C" wire is connected to "Y" on old thermostat. New thermostat has separate "C" hookup. Where does the blue wire go - "Y" or "C"? : r/Nest Blue "C" wire is connected to "Y" on old thermostat. New thermostat has separate "C" hookup. Where does the blue wire go - "Y" or "C"? : r/Nest](https://external-preview.redd.it/6zN1xZQzy-2LOwa4n34vHNhikW4WIakCRkDvcE2CErg.jpg?auto=webp&s=7175e52594e48d5481997b4225d26fe9259f9429)
Blue "C" wire is connected to "Y" on old thermostat. New thermostat has separate "C" hookup. Where does the blue wire go - "Y" or "C"? : r/Nest
![Am I compatible? There is also an addition yellow wire hidden in the back. Can't find anything referencing 1-4 like this. : r/ecobee Am I compatible? There is also an addition yellow wire hidden in the back. Can't find anything referencing 1-4 like this. : r/ecobee](https://i.redd.it/el03n2cye8k81.jpg)
Am I compatible? There is also an addition yellow wire hidden in the back. Can't find anything referencing 1-4 like this. : r/ecobee
![New Honeywell thermostat Th4110d1007 Wiring Diagram #diagram #diagramsample #diagramtemplate #wiringdiagram #dā¦ | Thermostat wiring, Thermostat, Digital thermostat New Honeywell thermostat Th4110d1007 Wiring Diagram #diagram #diagramsample #diagramtemplate #wiringdiagram #dā¦ | Thermostat wiring, Thermostat, Digital thermostat](https://i.pinimg.com/originals/5e/da/5e/5eda5e9992d59000eea869d297b8b052.jpg)