HVAC Terms

Commonly Referenced Residential HVAC Terms

Like any industry, the heating, ventilation and air conditioning (HVAC) business has plenty of terminology that can be confusing to an outsider. All of the acronyms and industry-specific language can limit your ability to truly understand what's being discussed. But our guide can help. Continue reading to learn common terms and phrases.

Residential HVAC System Equipment

Air Handler

Part of a central air conditioning or heat pump system that transfers heated or cooled air throughout a home's ductwork. This function may also be handled by a furnace.

Condensing/Outdoor Unit

Part of a central air conditioning system that is outside. It acts as a heat transfer point for collecting heat from outside air or dispelling heat to the outside air.

Heat Pump

An air conditioner with a valve that enables alternation between heating and cooling.

Single Package

A heating and air conditioning system with all components encased in one unit outside the home that is used throughout the year.

Split System

A heat pump or central air conditioning system with both in-home and outside-of-home components. This is the most often used system for homes.

Unit Components

Compressor

The pump that moves refrigerant in a cycle, from the indoor evaporator coil to the outdoor condensing unit and back to the evaporator. It acts as the heart of the system's refrigerant circulation.

Condenser Coil

A refrigerant-filled tube network that removes heat from hot refrigerant vapor. The vapor then condenses into a liquid, which absorbs more heat.

Evaporator Coil

Part of a heat pump or central air conditioning system inside the home. It acts as the heat transfer point for both warming and cooling air.

Efficiency Ratings/Measurement

AFUE %

Annual fuel utilization efficiency. This measurement is used for furnaces and indicates how efficient a furnace is at producing heat. Higher AFUE ratings indicate a more efficient product. The government's established minimum AFUE rating for a non-weatherized gas furnace vented through a chimney is 81%.

BTU

British thermal unit. It's a measurement of the amount of heat required to raise the temperature of one pound (or one pint) of water by one degree Fahrenheit.

HSPF

Heating seasonal performance factor. This measurement is used for heat pump efficiency. A higher HSPF rating indicates a more efficient heat pump. There isn't a government-established minimum rating for HSPF.

MERV

Minimum efficiency reporting value. This measures the efficiency of air filters. A higher rating means a filter is more efficient in capturing air particulates.

SEER

Seasonal energy efficiency ratio. This measures an air conditioner's cooling efficiency. Ratings can be as low as 13 or as high as 20 or more. An air conditioner with a 21 SEER rating, for example, is extremely efficient.

Ton

A ton is the cooling capacity of an air conditioning system. The measurement is equal to the amount of heat required to melt one ton of ice over 24 hours. A one-ton air conditioner would be rated at 12,000 BTU per hour (BTUh).

Additional HVAC Terms

ASHRAE

The American Society of Heating, Refrigeration and Air-Conditioning Engineers is a not-for-profit trade organization. Founded in 1894, its goals include the promotion and advancement of heating, ventilation, air conditioning and refrigeration system design and construction.

Balance Point

When a heat pump's output is exactly equal to the heating needs of the home. Typically occurs when the outdoor temperature is between 30° F and 45° F. When the outdoor temperature is below this point, the heat pump must use supplementary electric resistance heat to maintain temperatures indoor.

Heat Source

The air or liquid heat from which heat is collected. In Luxaire® heat pumps, for example, outdoor air acts as the heat source.

Load Calculation

Load calculation helps HVAC professionals determine what size system a home requires, based on heat gain or heat loss.

Supplementary Heat

Usually electrical resistance heat, supplementary heat is the auxiliary or emergency heat used when outdoor temperatures are below a heat pump's balance point.

Variable Speed

A motor that can operate at varying speeds for increased accuracy in the control of heated or cooled air in the home.

Speak with an Expert

Our Certified Comfort Experts are highly trained in home heating and cooling needs, and can provide you with a personalized solution that's right for your home.

Schedule a Home Consultation

Learn More