
Common HVAC Terms
Ever wonder what a condenser coil or compressor does? Or what "plenum space" means? Here’s a glossary of terms that will help you increase your knowledge of your HVAC system so you’re better equipped to ask questions and even diagnose problems yourself.
A
Type of compressor that uses a more efficient process for compressing refrigerant for better cooling efficiency.
B
A burner assembly within your oil furnace that provides combustion for heating oil.
C
The ability of a heating or cooling system to heat or cool a given amount of space. For heating, this is usually expressed in BTUs. For cooling, it is usually given in tons.
D
A movable plate located in the ductwork that regulates airflow. Dampers are used to direct air to the areas that need it most. Typically used in a zoning application.
E
The ratio of cooling capacity to the power input (in watts). The higher the EER rating, the more efficient the air conditioner.
F
A component of an HVAC system that adds heat to air or an intermediate fluid by burning fuel (natural gas, oil, propane, butane, or other flammable substances) in a heat exchanger.
G
A device that transfers heat from inside the furnace into the air outside the furnace. The duct system then transfers this exchanged air to different rooms in the building or space.
The part of a furnace that transfers heat to nearby air. That air is then distributed through the ductwork throughout your home.
I
Refers to the cleanliness of the air in a home. IAQ factors include particulate count (pollen, mold), humidity and volatile organic compounds (VOCs) found in a home’s air – all of which can aggravate allergy and asthma symptoms.
L
A series of studies performed to determine the heating or cooling requirements of your home. An energy load analysis uses information such as the square footage of your home, window or door areas, insulation quality and local climate to determine the heating and cooling capacity needed by your furnace, heat pump or air conditioner. When referring to heating, this is often known as a Heat Loss Analysis, since a home's heating requirements are determined by the amount of heat lost through the roof, entryways and walls.
M
The standard comparison of the efficiency of an air filter. Every air filter has holes that allow air and particles to pass through. The smaller the holes, the fewer particles that can pass through. Higher MERV ratings indicate smaller holes 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.
N
North American Technician Excellence (NATE) conducts rigorous, independent testing verifying the real-world knowledge and application of HVAC technicians and installers.
O
Part of an HVAC system that converts heating oil (similar to diesel) into high-temperate heat for the home.
P
Any substances measuring less than 100 microns in diameter. The EPA has found that small particles (less than 2.5 microns) are responsible for some of the most serious health effects of poor air quality.
R
The old standard for residential air conditioners, now being phased out by the U.S. EPA.
S
An energy efficiency rating for air conditioners. The higher the SEER, the more efficient the unit.
T
Usually found on an inside wall, this device controls heating and cooling equipment, allowing simple adjustments of temperature and other comfort control factors, such as humidity and airflow.
U
A nonprofit testing and research organization that sets standards for different product categories and tests products to make sure they meet UL certification standards.
V
A motor that provides a quiet, consistent flow of air for enhanced comfort, efficiency and humidity control. According to the Office of Energy Efficiency & Renewable Energy, a variable-speed motor running continuously at half speed may use up to 75% less power that a single-stage motor uses to move the same amount of air.
