Bryant 3 amp fuse blowing immediately

Jackdaw

I attempted to install a Nest thermostat yesterday (with Rh, G, C, Y1, W1 wires) but it reported no power, and sure enough 3 amp inline fuse was blown in my old Bryant Plus 80 furnace.

Assuming maybe I crossed a wire during install, even though circuit was off, I replaced the fuse, tried to power on furnace - fuse blows again immediately.

I disconnected and isolated all stat wires, fuse still blows when turning on power to furnace (circuit breaker and switch)

I reconnected the old thermostat (R, G, C, Y1, E/W1) and everything works as it was.


Wanted to confirm a couple things before calling in an expert.
Is it normal for the 3 amp fuse to blow when all stat wires are disconnected?

Could the system somehow be configured to only work with the old thermostat that is part of the Electric Co's power partner program?

Thanks in advance for any thoughts and feedback.

pecmsg

Jackdaw said:

I attempted to install a Nest thermostat yesterday (with Rh, G, C, Y1, W1 wires) but it reported no power, and sure enough 3 amp inline fuse was blown in my old Bryant Plus 80 furnace.

Assuming maybe I crossed a wire during install, even though circuit was off, I replaced the fuse, tried to power on furnace - fuse blows again immediately.

I disconnected and isolated all stat wires, fuse still blows when turning on power to furnace (circuit breaker and switch)

I reconnected the old thermostat (R, G, C, Y1, E/W1) and everything works as it was.


Wanted to confirm a couple things before calling in an expert.
Is it normal for the 3 amp fuse to blow when all stat wires are disconnected?

Could the system somehow be configured to only work with the old thermostat that is part of the Electric Co's power partner program?

Thanks in advance for any thoughts and feedback.

NO!