![Trying to replace this old 2 wire thermostat for a newer digital one. Problem is older unit does not have leads labeled or which cable is which. Any help on how to Trying to replace this old 2 wire thermostat for a newer digital one. Problem is older unit does not have leads labeled or which cable is which. Any help on how to](https://i.redd.it/j9mnonzn7nu91.jpg)
Trying to replace this old 2 wire thermostat for a newer digital one. Problem is older unit does not have leads labeled or which cable is which. Any help on how to
![My heat-only system only has two or three wires connected to the thermostat. Am I compatible with ecobee? My heat-only system only has two or three wires connected to the thermostat. Am I compatible with ecobee?](https://storage.googleapis.com/article_attachments/227874667/rwc.png)
My heat-only system only has two or three wires connected to the thermostat. Am I compatible with ecobee?
![My heat-only system only has two or three wires connected to the thermostat. Am I compatible with ecobee? My heat-only system only has two or three wires connected to the thermostat. Am I compatible with ecobee?](https://storage.googleapis.com/article_attachments/227874667/gasvalvefaststat.png)
My heat-only system only has two or three wires connected to the thermostat. Am I compatible with ecobee?
![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
![Room thermostat wiring tables: guide to generic or standard wiring connections for standard or generic room thermostats Room thermostat wiring tables: guide to generic or standard wiring connections for standard or generic room thermostats](https://inspectapedia.com/heat/Thermostat_Install_129_DJFs.jpg)
Room thermostat wiring tables: guide to generic or standard wiring connections for standard or generic room thermostats
![My heat-only system only has two or three wires connected to the thermostat. Am I compatible with ecobee? My heat-only system only has two or three wires connected to the thermostat. Am I compatible with ecobee?](https://storage.googleapis.com/article_attachments/227874667/gasvalvediagram.png)
My heat-only system only has two or three wires connected to the thermostat. Am I compatible with ecobee?
![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)