No matter what type of heating system you have or which fuel you use, your home will go cold when the lights go out. That’s because the thermostat relies on electric relays and switches to “call” for heat. The fuel pump is also affected by a lack of electricity, and if you have a furnace, so are fans and blowers.

In most cases, your thermostat will start functioning again after power is restored, although older programmable thermostats may need to be reset.