![Old Honeywell 2 wire AC thermostat (with 1 extra wire behind) - can I modernize this with Ecobee? : r/ecobee Old Honeywell 2 wire AC thermostat (with 1 extra wire behind) - can I modernize this with Ecobee? : r/ecobee](https://i.redd.it/old-honeywell-2-wire-ac-thermostat-with-1-extra-wire-behind-v0-zgb7bnf4hv2b1.jpg?width=3024&format=pjpg&auto=webp&s=260717dc10e09aa7edef141b700365ef3292e75f)
Old Honeywell 2 wire AC thermostat (with 1 extra wire behind) - can I modernize this with Ecobee? : r/ecobee
![Two 2 wire Honeywell digital thermostat to replace mercury switch. Convert from mercury switch - YouTube Two 2 wire Honeywell digital thermostat to replace mercury switch. Convert from mercury switch - YouTube](https://i.ytimg.com/vi/YqTUSs56E7A/maxresdefault.jpg)
Two 2 wire Honeywell digital thermostat to replace mercury switch. Convert from mercury switch - YouTube
![heating - Wifi thermostat to replace old mechanical 2-wire 110V Honeywell? - Home Improvement Stack Exchange heating - Wifi thermostat to replace old mechanical 2-wire 110V Honeywell? - Home Improvement Stack Exchange](https://i.stack.imgur.com/YnlT0.jpg)
heating - Wifi thermostat to replace old mechanical 2-wire 110V Honeywell? - Home Improvement Stack Exchange
![wiring - 2 wire thermostat wire want to be able to select fan only - Home Improvement Stack Exchange wiring - 2 wire thermostat wire want to be able to select fan only - Home Improvement Stack Exchange](https://i.stack.imgur.com/eH39I.jpg)
wiring - 2 wire thermostat wire want to be able to select fan only - Home Improvement Stack Exchange
![2 to 8 Wire All Thermostats Wiring Diagrams (Honeywell, Nest) | Thermostat wiring, Thermostat, Electrical diagram 2 to 8 Wire All Thermostats Wiring Diagrams (Honeywell, Nest) | Thermostat wiring, Thermostat, Electrical diagram](https://i.pinimg.com/originals/45/2d/cd/452dcd199d840f3929b6b52f03c0481b.png)
2 to 8 Wire All Thermostats Wiring Diagrams (Honeywell, Nest) | Thermostat wiring, Thermostat, Electrical diagram
![Wiring a Honeywell Room Thermostat - Honeywell or Resideo Thermostat Wiring Connection Tables & Hook-up Procedures Wiring a Honeywell Room Thermostat - Honeywell or Resideo Thermostat Wiring Connection Tables & Hook-up Procedures](https://inspectapedia.com/heat/Thermostat_Install_129_DJFs.jpg)