Compare Different Kinds of Furnaces

SINGLE STAGE

Single stage furnaces are on or off.   They run at 100%, every time.

TWO STAGE

Two-stage furnaces turn on at 60% of capacity (the first stage). If the call for heat isn’t satisfied, the furnace will kick up to 100% (the second stage). Often second stage will not be used, except in extreme weather conditions. As the furnace starts at a lower speed, there is no blast of heat. Making a two-stage is more efficient and quieter.

VARIABLE CAPACITY

A variable-capacity furnace will run as low as 35% of capacity. With 65 stages of heating, a variable-capacity furnace will adjust, in as small as 1% increments, to heat your home quietly, precisely, and efficiently.