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The Differences Between Single Stage, Two Stage, and Variable Speed Furnaces

There are three types of furnaces available on the market today. The system that will work best for your home is based on a number of factors, including heating requirements, existing ductwork and insulation, size and levels of your home, budget, and more.

Before you invest in a new heating system for your home, you should consult with a professional HVAC contractor, such as ARS (American Residential Services) Heating, Cooling and Plumbing. The Comfort Advisors and Service Technicians at ARS have a tremendous amount of experience in the industry analyzing homes to help a homeowner determine the best home heating system option.

The following are the three types of furnaces that may be suggested:

Single Stage Furnace
Single stage furnaces, also known as single speed furnaces, only have one stage of heat output – high. They continually disperse the maximum amount of heat that the furnace is designed for, regardless of the temperature outdoors or in certain areas of your home. Imagine yourself going from a walk to a full out sprint every time you wanted to work out. This is how a single stage furnace operates – there’s an “off” speed, and then an “on” speed with nothing in between.

This can be extremely costly for your energy bills in the winter since every time your furnace turns on, it’s dispersing the most amount of energy it possibly can.

Two Stage Furnace
Two stage furnaces, also known as two speed furnaces, operate much more efficiently than a single stage furnace. The first stage of this type of furnace operates the majority of the time in most climates, and runs at about 65% of the furnace’s full capacity. When the temperature outside becomes extremely cold and the first stage is not sufficient enough to heat your home, the second stage kicks on to provide the additional heat requirements. A 2 stage furnace provides the right amount of heat to efficiently satisfy your home and family’s needs.

In addition, a 2 stage furnace is much quieter since it doesn’t operate at 100% capacity every time it runs and creates less carbon dioxide emissions for the environment.

Variable Speed Furnace
Unlike a single stage furnace and 2 stage furnace, a variable speed furnace doesn’t actually refer to the number of stages your furnace goes through to provide heat; rather it refers to the fan motor in the furnace. In variable speed furnaces, the fan motor can move at different speeds to control the amount of heated air dispersed throughout your home. Better airflow results in a more comfortable environment in regards to both temperature and humidity.

Even when the furnace is not “on,” the motor in a variable speed furnace can still operate to continually circulate air throughout your home. This feature allows for healthier indoor air quality since your air is constantly passing through the filter in your HVAC system and being cleaned of such things as bacteria, viruses, and mold spores. In addition, this advanced control over airflow can eliminate the need for the furnace to operate as often since air is constantly being distributed throughout your home. This can result in less energy consumption and lower utility bills every month.

Some of the variable speed furnaces available are the most intelligent on the market. Though they may cost slightly more upfront, their savings can quickly be realized in saved energy costs over the lifetime of the equipment.

If you reside in the Washington DC Metropolitan, Northern Virginia or Maryland area, contact ARS Heating, Cooling, and Plumbing today to schedule a free estimate appointment with one of our trusted Comfort Advisors. They will listen to your comfort needs, analyze your home, and help you make the best heating installation decision for your family. Financing options are available. Visit to schedule an appointment online or call 888-242-4277.

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