11-26-2023 09:59 AM
I have a wood furnace with a gas backup, presently controlled by two separate Nest Learning thermostats, with the gas set fifteen degrees lower than the wood. I believe I should be able to wire both furnaces into a single thermostat, but the dual fuel wiring descriptions all assume that the primary "fuel" is a heat pump. Obviously if I have a wood fire going, I do not want the gas running on top of that, and once the fire goes out, I want the gas top come on. I'd like the gas to heat to a lower temperature. I think this means that I set up the wood furnace as primary and the gas as an emergency back up. Advice welcome!
11-30-2023 11:36 AM
Hi THW,
Thanks for reaching out to us. To control the wood and gas furnace thermostats, connect the wires from the wood furnace's "W" terminal to the Nest Thermostat's "W1" terminal, making the wood furnace the primary heat source. Connect the wire from the gas furnace's "Y" terminal to the Nest Thermostat's "Y1" terminal, allowing the Nest Thermostat to control the gas furnace as the backup heat source. Configure the Nest Thermostat settings to recognize the dual fuel system, specifying a "gas furnace" as the backup/emergency heat source. Adjust temperature differentials in the Nest thermostat settings to prioritize the wood furnace during operation and the gas furnace as a backup when needed. Follow on-screen prompts to setup your thermostat.
Let us know if that helps.
Best,
Zoe