I could use some advice.

This past summer I bought a house. The house has a carrier gas furnace and a/c unit. The previous owner or possibly the builder installed a heat pump thermostat. I'm having an issue with it. I'm hoping someone can help.

Whenever the heat kicks in, after a short while, the thermostat decides to kick in the auxiliary heat. Since its a gas system, I don't have aux heat, nor a heat pump. When it does this, it has the result of turning off the gas heat, leaving the system to just blow cold air. It does this until I turn it off, then turn it back on again.

Is there anyway to work around this so that the thermostat never kicks in the aux heat? I'd like to avoid buying a new thermostat but if I must than I will.

The thermostat is this one: http://www.residential.carrier.com/p.../premium.shtml

If I must replace the thermostat with a new one, how do I know if my system is a 1-stage or 2-stage heating system? Does it matter for which thermostat to buy? The house was built in 1998, so the system isn't terribly old.

Any help would be appreciated.

-Alex