Trying to use Nest 3rd gen to cycle fan for my wood boiler heat

[Woodboilerheat]

I have a wood boiler that circulates hot water through a heat exchanger in my air handler. I need to be able to cycle my fan by a temperature setting without activating any other heating source. Can I put a jumper wire between the W1 terminal and the G terminal to use the aux heat as a fan control?

[Woodboilerheat]

For anyone trying to figure this out, I finally figured out how to achieve the above stated scenario. I inserted an insulated wire in the W1 terminal that goes to nothing (dead ended). The thermostat sensed that I added the wire so I set it to electric forced air alternate heat and to use the alternate heat at all times. It turns the fan on and off at the set temp without turning on any heat strips or compressor. Shew… glad to figure this out!!!

[auslandjack2]

​Connecting a jumper wire between the W1 and G terminals on your Nest Learning Thermostat (3rd generation) to control your fan is not recommended. Nest thermostats are designed to function without jumper wires, as they have internal mechanisms to manage necessary connections. Inserting a jumper between W1 and G could potentially damage your thermostat or HVAC system.

To achieve fan control without activating additional heating sources, consider configuring your Nest thermostat's fan settings. By default, the fan activation for the W1 wire is set to 'Don't activate' because many forced-air systems handle fan control independently. However, if your system requires the thermostat to control the fan, you can change this setting to 'Activate.' This adjustment ensures that the thermostat will call for both the furnace (W1) and the fan (G) when heating. ​