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Common HVAC Terms and What They Mean

by VitalStorm Content on November 8, 2019

 Common HVAC Terms and What They Mean

If you find the vocabulary HVAC technicians use to be a little confusing, you aren’t alone. Most homeowners aren’t HVAC professionals, so the jargon technicians use is a mystery.  But never fear, the Blue Flame team has assembled this list of HVAC terms you might hear technicians use on the job.


Coils, also called evaporator or indoor coils, are where air conditioning comes from. Refrigerant is pumped through coils and, while in a gaseous state, absorbs heat and moisture from your home’s air. When the heat and water vapor is removed, your home’s air becomes cooler and drier.


The condenser is typically found in a big AC unit outside the home. The condenser returns the refrigerant to a liquid state, then releases the heat absorbed by the refrigerant into the outside air.


A damper is a plate or grate found in an air duct. Dampers control the amount of airflow into a home by increasing and decreasing friction between the air and the duct.


A duct is a passage that delivers hot and cool air throughout the home.


EER stands for Energy Efficiency Ratio. The EER is the ratio of output (cool air) to input (electricity).


The filter is a small grate of cloth-like material through which air passes before it enters your home. Air filters reduce the volume of particulates and impurities in your air-conditioned air.


Furnaces come in three varieties: natural gas, oil, and electric, and are the sources of heating for most North American homes. Furnaces warm the air, then motors in the furnace distribute this air throughout the home.


Grilles cover the vents through which air-conditioned air enters your home.

Heat Exchanger

Heat exchangers are devices that transfer thermal energy from one medium to another. HVAC systems have multiple heat exchangers including evaporator coils and condensers.

Heat Pump

A heat pump is a compression refrigeration system that can be reversed to provide either hot or cold air to a home.


HVAC stands for Heating Ventilation Air Conditioning. It is typically used to refer to heating and cooling systems found in homes, offices, and transportation systems.


IAQ stands for Indoor Air Quality.

Load Calculation

Load calculation is a test conducted by HVAC technicians to determine what size unit a home requires for appropriate heating and cooling. The calculation is based on square footage.


The SEER stands for Seasonal Energy Efficiency Ratio. Like the EER, the SEER is the ratio of output (cool air) to input (electricity); but, unlike the EER, the SEER only calculates this ratio on a seasonal basis, not a yearly one.


Single stage heating and cooling systems function like on/off switches. The furnace and air-conditioner each have one level and will run until the home’s temperature reaches what was programmed into the thermostat.

Split System

A split HVAC system has two main parts: an indoor unit and an outdoor unit. The indoor unit is typically a furnace, and the outdoor unit is typically an air conditioner.


Two-stage HVAC systems can operate at multiple levels. Instead of functioning like an on/off switch, two-stage systems can run at ‘medium’ or ‘high.’

Zoning System

A zoning system enables homeowners to maintain different temperatures in each room of their house.

Common HVAC Terms and What They Mean

Still need clarification on HVAC terms and what they mean? Our team at Blue Flame is happy to answer any and all questions you might have.