HVAC Terms Every Homeowner Should Know

April 13, 2011

Do you ever dread making phone calls regarding your heating & cooling system (by the way HVAC stands for Heating, Ventilating and Air Conditioning) because you don’t know the terminology? Knowing a few terms can help clear up a lot of confusion when discussing repairs or when purchasing of a new system. Below are some terms that are helpful for homeowners to know:

  • BTUh. British thermal units per hour. 12,000 BTUh equals one ton of cooling.
  • Compressor. The pump that moves the refrigerant from the indoor evaporator to the outdoor condenser and back to the evaporator again. The compressor is often called "the heart of the system" because it circulates the refrigerant through the loop.
  • Condenser Fan. The fan that distributes air over the air-cooled condenser.
  • Condenser coil (or outdoor coil). A series or network of tubes filled with refrigerant, normally located outside the home that removes heat from the hot, gaseous refrigerant so that the refrigerant becomes liquid again.
  • Evaporator Coil (or Indoor Coil). The other half of an air conditioning system, this network of tubes filled with refrigerant, which is located inside the home within the indoor unit, takes heat and moisture out of indoor air as liquid refrigerant evaporates.
  • HVAC. Heating, Ventilating, and Air Conditioning.
  • HVAC/R. Heating, Ventilating, Air Conditioning and Refrigeration.
  • MERV. Abbreviation for Minimum Efficiency Reporting Value. The MERV rating is the standard method for comparing the efficiency of an air filter. The higher the MERV rating, the better the filter is at removing particles from the air. The MERV scale ranges from 1 (least efficient) to 16 (most efficient), and measures a filter's ability to remove particles from 3 to 10 microns in size. Filters with higher ratings not only remove more particles from the air, they also remove smaller particles.
  • NATE. Stands for North American Technician Excellence. NATE-certified technicians are skilled professionals who have proven their knowledge in the HVAC/R industry by passing specialized NATE certification tests. NATE’s certification tests represent real world working knowledge of HVAC and HVAC/R systems.
  • Refrigerant. A chemical (working fluid) used in air conditioners, heat pumps and refrigerators to transfer heat into or out of an interior space. This fluid boils at a very low temperature enabling it to evaporate and absorb heat.
  • Refrigerant Charge. The required amount of refrigerant in a system.
  • SEER. Also known as the Seasonal Energy Efficiency Ratio. SEER is a measure of seasonal or annual efficiency of a central air conditioner (or heat pump). It takes into account the variations in temperature that can occur within a season and is the average number of BTU’s of cooling delivered for every watt-hour of electricity used by the air conditioner over a cooling season. The higher the unit's SEER rating the more energy efficient it is.
  • Split System. The combination of an outdoor unit (air conditioner or heat pump) with an indoor unit (furnace or air handler). Split systems must be paired for optimal efficiency. This is the most common type of system installed in a home.
  • Thermostat. A series of sensors and relays that monitor and control the functions of a heating and cooling system by turning the device on or off when a specified temperature is reached.

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Last Updated: June 09, 2023