Glossary
HVAC System Glossary
Prompt Response Time | Competitive Pricing | Since 1967
Prompt Response TimeCompetitive PricingSince 1967
Learn More About Technical HVAC and Plumbing Terms
If you ever wanted to learn what some technical HVAC terms mean in today's day and age, check out the list of glossary items listed below. Depend on the professionals at D & R Plumbing Heating and Air Conditioning Inc for all your HVAC and plumbing repairs. Call us today at (765) 362-1390 for the HVAC services you need.
A Brief Overview of HVAC-Related Glossary Terms
- AFUE (Annual Fuel Utilization Efficiency): A measure of a gas furnace's efficiency in converting fuel to energy - the higher the rating, the more efficient the unit. For example: A rating of 90 means that approximately 90 percent of the fuel is used to provide warmth to your home, while the remaining 10 percent escapes as exhaust. All new furnaces must have an AFUE rating of 78% or higher. An older furnace could be as low as 50%
- ACCA: Air Conditioning Contractors of America
- A-coil: see Evaporator coil
- AGA: American Gas Association, Inc
- Air handler: The indoor section of a split system air conditioner or heat pump. An air handler contains an evaporator coil and blower. Electric heaters or hot water heating coil can be added
- ARI: Air Conditioning and Refrigeration Institute
- ASHRAE: American Society of Heating, Refrigerating and Air Conditioning Engineers
- Boiler: A term used for unit that heats your house by pumping hot water or steam through radiators. Under-floor heating pipes and hot water coils with air handlers can also be used to distribute the heat. Unit can be electric, gas or oil fired
- BTU (British Thermal Unit): This is the amount of heat it takes to raise one pound of water one degree Fahrenheit. For your home, it represents the measure of heat given off when fuel is burned for heating or the measure of heat extracted from your home for cooling
- CFM (Cubic Feet Per Minute): A standard measurement of airflow. A typical system requires 400 CFM per ton of air conditioning
- Capacity: The output or producing ability of a piece of cooling or heating equipment. Cooling and heating capacities are referred to in BTUs
- Compressor: The heart of an air conditioning or heat pump system. It is part of the outdoor unit and pumps refrigerant in order to meet the cooling requirements of the system
- Condenser coil: The coil dissipates heat from the refrigerant, condensing the refrigerant from vapor to liquid. In an air-conditioner it is the outdoor coil, in a heat pump system it is the outdoor coil in cooling mode and the indoor coil in the heating mode
- Contactor: A switch that can repeatedly cycle, making and breaking an electrical circuit. When sufficient current flows through the coil built into the contactor, the resulting magnetic field causes the contacts to be pulled in or closed
- Crankcase heater: This is the electric resistance heater installed on compressor crankcases to boil off liquid refrigerant that may have combined with compressor oil. Many newer cooling systems do not require crankcase heaters, however heat pumps do require crankcase heaters
- Damper: Found in ductwork, this movable plate opens and closes to control airflow. Dampers can be used to balance airflow in a duct system. They are also used in zoning to regulate airflow to certain rooms
- Degree day: A standard industry measure of the coldness of the temperatures experienced, based on the extent to which the daily mean temperature falls below a reference temperature of 65 degrees Fahrenheit
- Dth (Dekatherm): Used on Natural Gas Bills. 1 Dth = 10 Therms. See Therms
- Ductwork: Pipes or channels that carry air throughout your home. In a home comfort system, ductwork is critical to performance - in fact, it's as critical as the equipment
- Electronic air cleaner: Air filtration unit that removes extremely small particles from the air by ionizing the particles then catching them on electrically charged collector plates
- Evaporator coil: The other half of your air conditioning system located inside your home in the indoor unit. This is where the refrigerant evaporates from a liquid to a vapor as it absorbs heat from the air that passes over the coil
- Freon: see Refrigerant
- Fuel rates: We're all charged for the energy we use. Electricity is sold by the Kilowatt, Propane and Oil are sold by the Gallon, Natural Gas is sold by the Therm. Fuel rates are used to calculate your annual heating and cooling costs. Gas, propane and oil rates vary from month to month, check several of your bills to get an average rate
- GAMA: Gas Appliance Manufacturers Association
- Gas furnace heat exchanger: Located in the furnace, the heat exchanger transfers heat to the surrounding air, which is then pumped throughout your home. A furnace that is 90% efficient or higher has two heat exchangers; a primary and a secondary
- Heat gain: Cooling load of a home. This is the amount of cooling required to cool your home. A heat gain calculation takes into account all the things that allow heat to enter from your house, such as windows, doors, R-values, walls, ceilings, floors, construction quality, number of people, roof color, attic ventilation, outdoor temperature, indoor temperature, etc. Heat gain is stated in BTU's or tons per hour. This is used to pick the size of cooling unit required for your home. It can also be used to estimate your annual cooling costs
- Heat loss: Heating load of a home. This is the amount of heat output required to heat your home. A heat loss calculation takes into account all the things that allow heat to escape from your house, such as windows, doors, R-values, walls, ceilings, floors, construction quality, number of fireplaces, outdoor temperature, indoor temperature, etc. Heat loss is stated in BTU's per hour. This is used to pick the size of heating unit required for your home. It can also be used to estimate your annual heating costs
- Heat pump: Basically an air-conditioner with a reversing valve and defrost control. In the summer, it absorbs heat inside your house and pumps it outside the house just like an air-conditioner. In the winter, it reverses the operation and absorbs heat outside your house and pumps it inside your house (It usually cost less to move heat than to it does to make heat). A heat pump will have an HSPF rating for heating efficiency and a SEER rating for cooling efficiency
- HSPF (Heating Seasonal Performance Factor): This rating is used in measuring the heating efficiency of a heat pump over an entire heating season. The rating is in BTUs per watt. The higher the number, the more efficient the unit
- Humidistat: A control which regulates humidity in the heating season by turning humidifier on or off
- HVAC: Heating, Ventilation and Air Conditioning
- Kw (Kilowatt): Measurement of electric power used, your electric bill is based on how many Kw you use per month. 1 Kw = 1,000 watts. If used to produce heat with resistive elements (electric furnace or electric baseboards) 1 Kw will produce 3413 BTUs
- Latent heat: A type of heat, which when added to or taken from a substance, does not change the temperature of the substance. Instead, the heat energy enables the substance to change its state (liquid to vapor or vapor to liquid). See sensible heat
- Package unit: A heating and cooling system contained in one outdoor unit. A package unit is typically installed either beside, on top of the home, or sometimes in the attic. See split system
- Refrigerant: A chemical that produces a refrigerating effect while expanding and vaporizing. Most residential air conditioning systems contain R-22 refrigerant (chlorodiflouromethane). R-22 is regulated by international controls under the Montreal Protocol and in the United States by the Environmental Protection Agency. It has a long life ahead of it as it is scheduled to be in production until the year 2020. It's used in approximately 95 percent of air conditioning equipment manufactured in the U.S. today. Equipment using R-22 cannot be manufactured after 2010. They must use a different type of refrigerant. The popular type currently used is R-410a (a.k.a. Puron®). Refrigerants are not interchangeable, the equipment must be designed for the type
- SEER (Seasonal Energy Efficiency Ratio): A measure of cooling efficiency for air-conditioners and heat pumps. Measurement is BTUs of cooling per Watt of electricity. The higher the SEER, the more energy efficient the unit. The government currently requires new units to have a minimum SEER rating of 13. Older units can be as low as 8 or even 6 SEER
- Sensible heat: That heat which, when added to or taken away from a substance, causes a rise or fall in temperature. See latent heat
- Split system: This is a combination of an outdoor unit (air-conditioner or heat pump) with an indoor unit (furnace or air handler). Split systems must be matched for optimum efficiency
- Therm: Measurement of gas usage, your natural gas bill is based on how many therms you used. One therm = 100,000 BTUS. On gas bills, this may be stated in Dekatherms (DTH). 1 DTH = 10 therms
- Thermostat: A thermostat consists of a series of sensors and relays that monitor and control the functions of a HVAC system
- Ton: A unit of measurement used for determining cooling capacity. One ton is the equivalent of 12,000 BTUs per hour
- Two stage: Some heating and cooling units can have more than one output capacity, giving them a high and low speed. Low speed would be used most of the time resulting in lower noise levels and more even temperature control and switch automatically to high speed when needed for the more extreme conditions
- Variable speed: Electronically controlled blower or fan motor that can vary its speed anywhere between its high and low settings. This allows for multi-stage heating and cooling. The electronic control can detect restrictions to the airflow and adjust the motor speed to always maintain the correct airflow. It can vary speeds during cooling to increase air-conditioner's efficiency and dehumidification. Dehumidistat can be added to further increase dehumidification. During continuous fan operations it can run at 50% for low noise levels and low operating costs
- Zoning: A method of dividing a home into different comfort zones so each zone can be independently controlled depending on use and need
Share On: