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Riley Heating & Air Blog

Multi-Speed vs Variable Speed Furnaces

Originally published October 2013, updated January 2017

It’s easy to confuse the terms variable speed and multi-speed when referencing the way a furnace works. Both terms, which apply to the blower motor of the furnace, have very independent meanings. Both options are designed to improve the way furnaces operate so that they enhance comfort and improve energy efficiency.

Understanding Variable Speed and Multi-Speed Furnaces

A variable speed furnace will automatically change modes to regulate heating output. This type of blower has an intelligent design that controls the specific needs of each room. A variable speed blower motor will sense any restrictive elements to the airflow, such as a clogged air filter, and compensate by ramping up the blower’s power. Additionally, the blower fan remains in the on position most of the time. However, the fan automatically runs at a more efficient level of airflow as needed. Along with the right thermostat, the intelligent design allows for a consistently optimum humidity level as well.

Many older furnaces are either on or off and so are considered to be single stage. They provide the same level of heating regardless of the demand. Today’s efficient multispeed options operate at two or more speeds. The two-speed models are more common, operation at either high or low speeds. Multispeed versions allow for more precise temperature control.

How Do I Choose Between Variable And Multi-Speed?

A variable speed furnace is more efficient in adapting to your heating needs and requires less electricity to power the motor. An energy audit is always the best place to start prior to choosing a new system. An analysis of the building’s floor plan and duct system, in addition to load calculations and budget, determines the best type of furnace for any HVAC need. Choosing the right furnace is crucial for humidity control. You will also avoid overworking the unit and shortening its lifespan. For more help with making the right decision for your family, call Riley Heating & Air Conditioning today at 334-298-1278.

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