New Thermostat - 24V from furnance

thone

I would like to install a new thermostat (wi-fi) which requires external power.

I found 24V terminals from the furnance, however, they are already in used. (One connect to motor, I am not sure about the other). Can I hook this new thermostat on to it?

biggles

...they mean 24Vs constant on the subbase from the furnace you shold alraedy have R at there,so you need the C side of the transformer in the furnace so you read 24V with just the subbace wired or before connecting it to the base...stay away from the motor side and the 115Vs within the furnace...reason you need a constant 24Vs is the draw on the new stat solid state within...if you just used the R without a C pulled up there the stat would light up but have no action