Question about 2-stage heating thermostats

[kcroat]

I have a dual fuel system (heat pump and gas boiler with no supplimental electric) that I want to control with the same thermostat. I'm looking at a cheaper White-Rodgers model (1F85-277) as I don' have problems programming them. It is two-stage and has W1 and W2 terminals (for heat pump and gas boiler, respectively). However as I understand it the normal configuration for heat pump t'stats is for W2 to be hooked to supplimental electric heat, which is called for only when the heat pump (on W1) can't keep up. When it is too cold, I'd like to be able to not use the heat pump at all and go straight to the gas boiler (on W2). Do the typical 2-stage heating thermostats allow you to do this or do I need a more expensive model (other White-Rodgers or Honeywell)?

Thanks.

[BaldLoonie]

You will need something besides that stat. I'd suggest Honeywell's Vision Pro TH8320. With the outdoor sensor, it will do just what you want. Available through heating dealers. Not sure if the consumer version will work for what you need.

[key]

be carefull of dual voltage, keep in mind that you will have to install an isolating relay...

[smokin68]

Originally posted by kcroat
). However as I understand it the normal configuration for heat pump t'stats is for W2 to be hooked to supplimental electric heat, which is called for only when the heat pump (on W1) can't keep up. When it is too cold, I'd like to be able to not use the heat pump at all and go straight to the gas boiler (on W2). Do the typical 2-stage heating thermostats allow you to do this or do I need a more expensive model (other White-Rodgers or Honeywell)?

Thanks. [/B]

This isn't how a normal heatpump works. The w1 is actually your electric heat backup. The reversing valve is your 1st stage of heat. That said,if all of your controls are 24v, you can hook up almost any hp stat to do what you want as long as you install a remote sensor(normally closed) on the compressor circuit that opens on a drop in temperature,and the stat has the capability of calling for backup on it's own. Call a pro and have a Visionpro installed, like BL said.

[docholiday]

Is theboiler feeding a water coil in the duct or baseboard?

If its feeding a coil I wouldnt shut down the HP. I would have the water coil installed after the indoor HP coil and bring it on with W2 or outdoor temperature sensor. An aquastat would be another good idea for this application. If its baseboard you still arent saving anything by shutting down the HP. You could always add a zone and put the water coil in. Its got to be after the HP coil in either case.