What is the two-stage heating or cooling?
Two-stage means that the system can have two distinct operational output. In general, the two-stage control is more complicated than the traditional single-stage system. It is prefered to equip a two-stage thermostat for the 2-stage system. But the existing wiring from the thermostat to the furnace can be a problem. Most of manufacture has its own control logic to let single-stage thermostat to work with a 2-stage furnace. Advantages of two-stage including the performance, efficiency, confort level etc. The initial price and maintenance cost for the 2-stage system are in general higher than that of single-stage system.
