I am upgrading my thermostat to a Nest, and would like to add a common wire. My current furnace controller doesn't have a C terminal, but the current thermostat wire has 2 unused wires (black and blue)
what's the best way to do this?
On the 24V side of the transformer there is: 1 Red Wire 3 Blue Wire - 1 Blue is ground - 1 Blue goes to gas valve - 1 Blue goes to furnace controller
Can I cut one of the blue wires, lets say the one to the controller, strip the ends and connect both ends to the c-wire on my thermostat wire?