[Kedro]

How do you wire a thermostat to run a fan blower only on a gas furance

 

[Missouri Bound]

It's not always possible. If a thermostat has a fan switch AND the furnace control allows it you should be able to make it work with simple thermostat connections. The control board of the furnace will be ready for this connection. What wires are you working with to the thermostat? Got a picture? What connections are at the furnace?

 

[how]

If your furnace predates a control board, it's still possible to do with a fan relay if you have a thermostat with a fan switch and an available line to carry the switching 24V.

 

[biggles]

you have to chase the fan cycle into the heating signal if you have a control module:wink: it will come off that on a delay with that black relay board mounted you see with arating tag stamped

 

[hvactech126]

How do you wire a thermostat to run a fan blower only on a gas furance

More info about your setup is needed to be truly helpful.