Thermostat Help

angel1971

I replaced an old thermostat with a Hunter Universal thermostat and followed the instructions to the letter. Ran into a problem!! There is only one slot for E/W2 wire. I have both the E and the W2 wires. I put them in the same slot but it just dont feel right to do that. What do I do?

thehvacguy

What kind of furnace do you have? I dont recall ever seeing an e terminal. I know w2 is the terminal for the second stage of heat in a two stage furnace.

unicursalhex

You didn't mention what kind of equipment you're running. The terminals are different for heat pump than for conventional, make sure you're reading the right line

thehvacguy

What terminal is e for? Is it for humidifier?

beenthere

Emergency heat, on a heat pump.

beenthere

Either leave them both in the same slot. Or get a thermostat with separate E and W2 terminals.

thehvacguy

By emergency heat are you referring to the electric heat strips that come on during defrost?

beenthere

That would be aux, or back up heat.

Emergency heat is the same heaters. But is only controlled by the thermostat when the thermostat is turned to emergency heat. When set to emergency heat, the heat pump does not run.

thehvacguy

I dont understand, if the heat pump doesnt run during emergency heat, then where does the heat come from? And what is the purpose of the emergency heat function?

unicursalhex

It runs a backup heat source, usually electric heat strips in the air handler, for dual fuel systems it usually runs a gas furnace. The purpose(s) of emergency heat is to run at lower temps (usually around 30 degrees) when the heat pump can no longer extract enough heat. It can also be used as another heat source if the heat pump goes out.

beenthere

Majority of all heat pumps have an aux heat source. This heat source is also the emergency heat when the heat pump is non functional.

As uni posted. It can be electric strip heaters, gas furnace or boiler, oil furnace or boiler.