Basic HVAC Terms Glossary

Basic HVAC Terms Glossary

AC (Alternating Current): A type of current where the polarity is perpetually reversing, causing the directional flow in a circuit to reverse at regular intervals.
AFUE: Annual Fuel Utilization Efficiency (AFUE) quantifies furnace efficiency by comparing heat output to heat input.
Air Conditioner: A device that changes humidity levels, temperature or quality of air.
Airflow Volume: This is the amount of air circulated in a space.
Air Handler: Indoor part of the air conditioning system including the circulating fan and evaporator.
Burner: The device that facilitates the combustion of air and gas.
Capacity: HVAC capacity is the output produced by the heating or cooling unit and is measured in BTUs per hour.
CFM (Cubic Feet per Minute): A measurement of airflow volume.
Charging a System: Adding refrigerant, to an HVAC system.
Compressor: A pump that increases the pressure of refrigerant gas.
Condensate: As warm air is pulled or pushed across the cool evaporator coil the coil perspires, creating liquid, or condensate which is mechanically drained away from the equipment.
Condenser Coil: Generally the outdoor coil, it removes heat from the refrigerant in the summer months, allowing the refrigerant to be converted from vapor to liquid and complete the refrigeration process.
Condenser Fan: A fan moves air over the condenser coil, and causes the removal of heat from the refrigerant.
DC: Direct Current. A type of electrical current that only flows in one direction.
Dehumidifier: A device that removes moisture, from the air.
Drain Pan: The drain pan collects the condensate and funnels it to the drain line.
Dry Bulb Temperature: The temperature as measured without the consideration of humidity.
Duct work: Metal, fiberboard or flexible material flowing throughout a space which delivers air to different areas in a home or office.
EER: The Energy Efficiency Ratio of a cooling device is the ratio of output cooling energy (in BTU) to input electrical energy at a given operating point.
Evaporator Coil: A device that is designed to absorb heat in the air in order to change the liquid refrigerant that flows through it into a vapor initiating the cooling process.
Fahrenheit: A temperature scale in which water freezes at 32 degrees and boils at 212 degrees at normal atmospheric pressure.
Fan: A device consisting of a motor and a blower wheel that moves air.
Filter: The air filter, prevents contaminants from entering the equipment.
Flue: A furnace vent serves to expel the combustion byproducts generated during the operation of a furnace
Furnace: A gas-fired heating component commonly used in homes. It enables the combustion of fuel and air to generate heat, which is then distributed throughout the house via a fan.
Fuse: A delicate metal strip connecting two parts of an electrical circuit.
Heat Exchanger: A device through which heat is transferred
Heat Gain: The amount of heat added in area.
Heat Loss: The amount of heat lost from a designated area.
Heat Pump: A device used for either the heating or cooling of a space
Heat Transfer: The flow of heat from one area to another by conduction, convection, and/or radiation. Heat flows naturally from hot to cold.
Humidifier: A device that adds humidity, or moisture, to the air.
Ignition: a combustive reaction.
Latent Heat: Hidden heat
Orifice: An opening or hole in a object.
Package Unit: A heating and cooling system all in one.
Plenum: A plenum is a compartment housing gas, often air, at a positive pressure level exceeding the surroundings. One of its roles is to regulate and balance pressure to ensure uniform distribution.
Programmable Thermostat: A type of thermostat that allows the user to program into the devices' memory a pre-set schedule of times and temperatures enabling or disabling the HVAC equipment.
PSI: A pound per square inch is a unit of pressure resulting from the force of one pound-force applied to an area of one square inch.
PSIA: Pounds per square inch absolute (psia) denotes pressure relative to a vacuum, distinguishing it from ambient atmospheric pressure. At sea level, atmospheric pressure is approximately 14.7 psi, which is added to any pressure measurement taken in air at sea level.
PSIG: Pounds per square inch gauge designates that the pressure is relative to atmospheric pressure.
Refrigerant: Refrigerants, the working fluids in air conditioners, heat pumps, and refrigerators, facilitate heat transfer into or out of an interior space. These compounds have low boiling points, allowing them to absorb and release heat effectively
Refrigerant Charge: The amount of refrigerant in a system.
SEER The efficiency of air conditioners is often rated by the Seasonal Energy Efficiency Ratio which is defined as the cooling output during a typical cooling-season divided by the total electric energy input during the same period.
Sensible Heat: Heat added or subtracted that causes a change in temperature.
Single-Speed Motor: Single-speed motors operate at their maximum speed until reaching the desired temperature, then they stop. They , consume higher energy levels compared to other motor types.
Split System: A split system consists of an outdoor unit an indoor unit.
Thermostat: A wall mounted device that monitor and controls the output of an HVAC system.
Thermostatic Expansion Valve: A device that creates a constant evaporator temperature by regulation of refrigerant flow through the system.
Ton: One ton is 12,000 BTUs per hour.
Two-Speed: The base required for a high-efficiency air conditioner, two-speed motors cycle on in low gear and attempts to satisfy the cooling load for the home, shifting to high gear if necessary. Once it reaches the desired temperature, it cycles back down to low before shutting off. With just two speeds, it reduces start-up noise, operates with greater energy efficiency and causes less stress on mechanical parts compared to single-speed motors.
Upflow Furnace: A furnace that pulls in air from the bottom and releases it through the top.
Vacuum: A space where the pressure is significantly below that of standard atmospheric pressure.
Variable-Speed: Ideal for high-efficiency air conditioners, a variable-speed motor functions much like a two speed, only with several speeds of operation. When compared with single- or two-speed motors, it facilitates smoother cycling and more precise performance control, as well as the most quiet operation, highest energy efficiency and least stress on mechanical parts.
Ventilation: The process of moving air (changing) into and out of an interior space either by mechanically induced (forced) means.
Volt: Is the derived unit for electrical potential and electromotive force.
Voltage: The force pushing electrical current along wires and cables.
Zoning: A zoning system is a setup that divides a home, office, or space into distinct regions to enhance temperature control and optimize the efficiency of a heating and cooling system.