A two-stage furnace offers more efficiency than a single-stage furnace. It offers the precise heating and cooling your home needs at any given time and, in addition, operates very quietly. What’s more, two-stage furnaces are eco-friendly, as they do not produce significant amounts of carbon dioxide during operation.
Given the information above, most customers opt to secure a variable speed, two-stage furnace. Even if you’re only in the market for a heat pump, the same principles apply – look for pumps with two-speed compressors accompanying a variable speed air handler.
The working principle
For most climates, the unit works in the first stage, operating at about 65% capacity. As soon as the outside temperatures drop to extreme levels, the second stage comes on to support the first stage with additional heat requirements. This results in much warmer air in your room, as well as a reduction in air fluctuations.
Note:
While variable speed refers to the blower motor, two-stage denotes the gas valve and burners. Variable speed refers to the amount of air flowing through the ducts, while two-stage refers to the amount of heat sent out by the furnace.