What is the Difference Between First-Stage, Two-Stage and Variable Capacity Furnaces and Air Conditioners?

Compare Different Kinds of Furnaces

There are three kinds of furnaces* available, today.  Know your options.  

Please see the chart and diagram below to understand the differences.

*While this post specifically describes furnaces, the same applies for air conditioners.  

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.

Know your options! 

If you need more information, please contact Otto, here.
To see our selection of furnace, please click here. For our air conditioners, please click here.