When shopping for furnaces, homeowners will come across the terms one-stage and two-stage. This choice presents differences in purchasing, operating, and repair costs due to the way these furnaces work. Single-stage furnaces always operate at 100% power, while dual-stage furnaces can operate at 70% or 100% power.
The main benefit of a one-stage furnace is its price. Not only are these furnaces more affordable to purchase, but they are durable and less expensive to repair than two-stage furnaces. Two-stage furnaces have a higher cost due to the second heat exchanger and may cost more to repair; although, they are just as durable. Aire One, a heating and cooling company being in this industry for over 30 years, have experience with both types and is able to make repairs.
Because most one-stage furnaces have a blower that operates at max speed and volume, the furnace blows more cold air through the ducts than a two-stage furnace, which typically has a multi-speed blower that blows less forcefully before the furnace has fully heated up. For this reason, single-stage furnaces have a greater temperature variability. A one-stage furnace can swing up to 4 degrees while a two-stage furnace has temperature swings of only one or two degrees.
Another benefit of a two-stage furnace is its longer cycle, which enables the air in your home to be pulled through the furnace more frequently than with a one-stage furnace. Although this is not as effective as running an air purifier, it does remove more dust and debris from the air. The longer cycles also cause a humidifier that’s connected to the HVAC system run longer, producing a more comfortable indoor climate.
When it comes to efficiency, two-stage furnaces are more efficient. The longer cycle runs more consistently at lower power. These furnaces have efficiency ratings between 95% and 97%, while single-stage furnaces have slightly lower efficiency ratings of between 90% and 95%. This efficiency can make up the price difference over the life of the furnace.