Google Nest Community

Same issue. Nest is short cycling, but backup thermostat works fine.

Same issue. Nest short cycles on heat. Previous thermostat does not. C wire connected.

Same issue. Nest short cycles on heat.

The C wire comes from the A/C, not the furnace. The furnace could be short cycling because nest steals power from the Rh wire while heat is running.

This issue still persists. When I have Y1, G, Rc, W1, Rh, and C all connected, the boiler short cycles. The A/C did not have this issue during the summer. I have gone back to a regular thermostat in the meantime to protect my boiler.