These are the HVAC Heating Season Terms to KnowThe more you know about your heating system, the better choices you can make for HVAC efficiency, service, repairs and when you’re installing a new unit. Though, you don’t need to become an expert, but understanding basic heating season terms is a great start!


When you’re shopping for a new furnace, you probably want to compare energy efficiency between different models. The Annual Fuel Utilization Efficiency (AFUE) rating does just that. The AFUE rating of any furnace indicates the percentage of fuel that is converted to heat energy. The higher the AFUE, such as 97 AFUE, the greater energy efficiency.


The Heating Seasonal Performance Factor (HSPF) number represents heating efficiency for heat pumps. It is the ratio of heat output to energy input.

Variable-speed Furnace

A variable-speed furnace is one that employs sophisticated equipment that delivers heating output to your home at variable speeds. Variable-speed furnaces offer the highest AFUE ratings and, when properly installed, keep your home comfortable to within a degree of the thermostat setting.

Heat Pump

Heat pumps utilize the natural properties of refrigerant to transfer heat energy, rather than use a fuel to make heat. Heat pumps typically aren’t as efficient for home heating as furnaces in the Indianapolis area. However, when combined with a furnace in a dual-fuel system, they are excellent home comfort solutions that also provide home cooling during summer.

Heat Exchanger

Your furnace’s heat exchanger consists of material that transfers heat energy from the combustion compartment to airflow inside the air ducts. Your HVAC pro should inspect the heat exchanger each year for cracks.


MERV is an acronym for Minimum Efficiency Reporting Value. MERV is used to designate the efficiency of air filters. The higher the MERV rating, the better capturing qualities a filter delivers. Stock up on air filters to last you through the heating season, and try to choose filters with MERV 7 to 12 ratings for optimal HVAC efficiency and IAQ performance.

When you have HVAC questions or need furnace service or repair in the Indianapolis area this heating season, contact Mowery Heating, Cooling and Plumbing.

Our goal is to help educate our customers in Brownsburg, Indiana and surrounding areas about energy and home comfort issues (specific to HVAC systems).

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