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. This HVAC glossary has some of the most popular acronyms and industry-specific language homeowners will experience in their HVAC purchase.
Home 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.
HVAC 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.
HVAC Efficiency Ratings and Measurements
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).