Experts recommend 90% furnaces for most homes. A 90% or 92% AFUE furnace has enough efficiency to merit state or utility energy conservation rebates in many states, even though initial costs can be $1,000 more than an 80% furnace. A 90% furnace wastes about 10% less heat, and therefore is cheaper to operate. HVAC experts say the difference between an 80% furnace and a 90% furnace is greater than the difference between a 90% furnace and an ultra-high efficiency 92% to 96% furnace.


Multi-Stage furnaces

Experts and homeowners alike agree that multi-stage furnaces produce the greatest level of comfort. While conventional furnaces cycle on and off, two and three-stage furnaces use variable-speed blowers to maintain a nearly constant temperature. They are cheaper to operate. As an example, the Bryant/Payne has a modulating burner with a heat output range from 40% to 100% in 5% increments. This reduces wear and tear on the motor and increases efficiency, lowering operating costs.


Smaller HVAC systems usually cost less to buy, and those savings often spur people to upgrade to high-efficiency equipment. The money saved also offsets the cost of the professional load and sizing calculations. Properly sized equipment operates longer at maximum efficiency; oversized equipment runs for shorter periods (short cycling). It’s similar to a car getting worse mileage in stop-and-go traffic. In warm, humid weather, HVAC systems also remove moisture from the air. Oversized systems remove less moisture due to short cycling, leaving the indoor environment more humid. Properly sized equipment will last longer, as it will start and stop less often.

Resource: Heating and cooling Racine