Glossary Terms

HVAC Definitions

Air Cooled System - A type of air conditioning system that uses air as the condensing medium and R-22 or R-410A as a refrigerant. In most air cooled systems, the condenser is located outside and the refrigerant is piped to it from the indoor unit. In air conditioning, the heat from the indoor space is transferred to the outside air. In a heat pump, the heat is drawn from the outdoor air and is used to heat the indoor air.

Air Handling Unit (Air Handler) - The portion of the central air conditioning system that moves heated or cooled air throughout a home’s ducts, though it does not include the ductwork. Typically, it is located inside and includes blowers, dampers and other equipment in direct contact with air flow.

Blower - A piece of equipment designed to move air through a system. Usually refers to the air handling unit or air handler.

Charge - The amount of refrigerant in a system.

Coil (Indoor Coil) - Equipment that enables heat transfer to and from the refrigerant and the air when installed inside an air handling unit. The indoor coil often features two rectangular coil surfaces connected at the top and open at the bottom. From the side, this configuration looks like the letter ”A”.

Compressor - The ‘pump’ that circulates vapor refrigerant throughout the system from the indoor evaporator to the outdoor condenser and back.

Condenser Coil -A series of tubes filled with gas (vapor) refrigerant that carries heat from the home and removes it outdoors allowing the refrigerant to condense or liquify and start the process again.

Condensing Unit - A device that condenses a substance from a gaseous to a liquid state, typically by cooling it. In the process other latent heat is given up by the substance and will transfer to the condenser coolant.

Dual Fuel System - A heating solution that combines a furnace and a heat pump to provide an economical way to heat a home. A heat pump is activated for moderate heating needs and a furnace is switched on when higher levels of heat are needed. This system helps maximize the energy efficiency of each unit.

Ducts - Ducts are channels that carry cooled air from the air conditioning unit throughout your home and are responsible for removing warm or stale air. Ducts that are for central air conditioning can also function for filtering and heating systems.

Ductless Mini-Split - A type of air conditioning system that does not use ducts to transfer cool air and instead the outdoor condenser unit is connected directly to an interior air handler. Because of this direct connection, generally only one room or space can be cooled at a time making ductless mini-splits a viable option for room additions or add-ons, but potentially troublesome for whole-home solutions.

"AC" - (Air Conditioner) - HVACA system or assembly comprised of certain system components which are designed for the control of air temperature, relative humidity and air flow in a living or working space.

EER - (Energy Efficiency Ratio) - A ratio to determine the energy efficiency of an air conditioner. The higher the EER Rating, the more efficient the unit. EER Ratings are generally lower than SEER ratings because SEER are seasonally adjusted while EER ratings are calculated against a fixed ambient temperature.

Efficiency - A measure of how much energy is used to accomplish a cycle, measured by Seasonal Energy Efficiency Ratio (SEER) or Energy Efficiency Ratio (EER). The higher the rating, the more efficient a system is and the lower your energy consumption will be.

Evaporator Coil - A series of tubes filled with liquid refrigerant that absorb heat from the air as the liquid refrigerant is ‘evaporated’ into vapor.

Fresh Air Intake - An opening through which outdoor air is drawn into a system.

Furnace - The component in an HVAC system that adds heat to air by burning fuel in a heat exchanger.

Heat Pump - An air conditioner that has a reversing valve allowing it to alternate between heating in the winter and cooling in the summer.

HSPF - An industry term that stands for Heating Seasonal Performance Factor. It is a measure of efficiency for air source heat pumps. A higher number represents higher efficiency.

Humidity - A measure of the amount of moisture in the air.

HVAC - A term that stands for Heating, Ventilation, and Air Conditioning.

Load Calculation - A measure to determine heat gain and loss within a structure so that properly sized HVAC equipment can be installed.

Payback Analyst - A measure of the value of your system that determines the number of months required before monthly energy cost savings offset the purchase price.

R-22 - An HCFC (hydro chlorofluorocarbon) refrigerant, often referred to by a brand name such as Freon®, used primarily in residential air conditioning systems. It is being phased out for its higher global warming potential (GWP) and ozone depleting properties.

R-410AA - Non-ozone depleting refrigerant that has replaced R-22 as the preferred refrigerant of choice in the U.S., Japan and Europe. R-410A performs at a higher pressure than R-22 and requires the use of different equipment than with R-22.

Refrigerant - A chemical, usually a vapor, which can be used in a mechanical system to produce a cooling heat transfer effect while changing the pressure of the refrigerant. Many air conditioning and refrigeration systems use refrigerants which change from vapor (gas) to liquid and back to a vapor during the heating and cooling process.

Relative Humidity - The ratio of the amount of moisture in the air compared to the amount of moisture the air could hold at the current temperature, expressed as a percentage.

Return Air - The air drawn into the heating unit after having been circulated through a room.

Room Air Conditioner (Window Unit) - Standalone air conditioning unit that cools only where needed, usually installed in a window space. Generally, less efficient than central air conditioning, but less expensive to operate.

System A general term that refers to the set of components that perform an HVAC function.

SEER - A rating that expresses the efficiency of air conditioning equipment throughout an entire average cooling season, including both the hottest and coolest days. It stands for Seasonal Energy Efficacy Ratio. The higher the SEER rating, the more efficient the system.

Split System - The most common type of residential system, it consists of two main components – a compressor and condensing unit installed outdoors, and an air-handler installed indoors.

Tonnage - A unit of measure used to describe the cooling capacity of an air conditioning system. One ton of cooling is the amount of heat needed to melt one ton block of ice in a 24-hour period.

Zoning - A method of providing independent heating or cooling to different areas or rooms within a building or home, typically controlled by separate controls or by opening or closing the vents and ducts in each zone.

Plumbing Definitions

Angle Stop - An angled stop is a shutoff valve between the water supply and plumbing fixture. It is used to shut off water flow while you repair the connected item.

Anode Rod - An anode rod is located inside the water heater. The anode rod protects the water tank from corrosion due to magnesium or aluminum.

Backwater Valve - A backwater valve prevents disposed sewage from reentering the home.

Ball Check Valve - A ball check valve is a type of backflow preventer. The ball check valve is placed on a water line to direct water flow in one direction.

Ballcock - The ballcock controls the flow of water in a gravity-operated toilet tank. When the toilet is flushed, the circular float will drop and open the ballcock. This results in water being distributed in the tank. As the water rises, the float rises to the level that shuts off the ballcock.

Branch - A branch is any secondary part of the drain system; also, referred to as the lateral line.

Branch Vent - A branch vent connects vents with a vent stack.

Check Valve - The check valve is a type of backflow prevention. The check valve is installed on a pipe to allow water flow in one direction.

Cleanout Plug - The cleanout plug is in a trap or drainpipe. The cleanout plug offers access to the drain line for clearing any blockage in the pipes.

Closet Synonym for a toilet, also referred to as a “water closet”.

Closet Auger - A closet auger is a flexible rod that is used to access a toilet’s trap to remove any clogs.

Access Panel - An access panel is an opening in a wall or ceiling near a fixture. The panel offers access to work on plumbing or electrical systems.

Closet Bend -The closet bend connects the closet flange to the toilets drain.

Closet Flange - The closet flange is a ring that anchors the closet bend to the floor. The closet flange also includes closed bolts that secure the toilet in place.

Diaphragm - The diaphragm is a flexible membrane that helps regulate water flow and build up within a Valve.

Dip Tube - The dip Tube sends cold water to the bottom of the water heater tank.

Drip Leg - The drip leg, also known as the “sediment trap”, is a pipe installed at the lower segment on a gas line. The capped off section collects condensation and debris.

Escutcheon - The escutcheon is a protective cover under the faucet handle that masks the fixtures hole.

Fall/Flow - The fall, also known as flow or pitch, refers to the slope needed to create proper drainage in pipes.

Fixture - A fixture refers to the plumbing device that provides water and/or disposal. Common fixtures in plumbing are toilets, sinks and showers.

Flapper Valve - The flapper valve connects the water tank and toilet bowl. When the flapper valve opens, water flows from the tank into the bowl.

Float Ball - The float ball is the plastic ball attached to the ballcock. The rise and fall of water in the tank is determined by the float ball’s placement.

Floor Flange - The floor flange, also known as a closet flange, connects a toilet to the sewer line.

French Drains - French drains provide an easy channel for water to flow through. Water runs into a gravel-filled trench, then into perforated pipe at the bottom of the trench. Water travels freely through the pipe, which empties a safe distance from the house.

Gas Cock - The gas cock on a main gas line allows for the gas to be shut off.

Gate Valve - The gate valve controls the flow of liquids in pipes.

Gravity Operated Toilet - A gravity operated toilet relies on downward pressure of water in a toilet tank to flush. Gravity operated toilets often have ball cocks in their tank.

Gray Water - Gray water is any wastewater that comes from common fixtures, but not toilets.

Horizontal Branch - The horizontal branch runs from plumbing fixtures to a waste stack.

Horizontal Run - Horizontal run is the distance liquid travels from the entry point and exit of a pipe.

Nipple - A nipple is a short pipe that connects couplings and other fittings.

Hose Bib - A hose bib is a common outdoor faucet. Sometimes called a spigot.

Main Line - The main line supplies water from the water company’s meter at street level to the main branch of pipes around your home.

Power Flush System - The power flush system compresses water to provide a pressurized flush. This system is often found in business and commercial settings.

PRV - or "pressure reducing valve", is a special valve that is installed directly on the main water line. The PRV constrains the amount of water entering from the water companies supply to normalize water pressure for home use.

PVC - PVC pipes are sturdy plastic pipes that are used for drainage, waste and vent systems.

Rim Holes - Rim holes are a series of small holes around the toilet bowl. Water flowing from the rim holes.

Saddle Valve - The saddle valve is a mounted pipe run by a clamping device. The saddle valve is used to make quick connections between low-demand devices.

Septic Pumping - Septic Pumping is the process of removing sludge from the bottom of the septic tank, and this needs to be done before the sludge builds up to a level where it blocks the outlet pipe through which liquids flow into the drain field.

Septic Tank - A septic tank is a small sewage treatment system for homes with no connection to local sewage pipes. Septic refers to the bacteria the decomposes the waste inside the tank.

Straight Stop - Valve A straight stop valve is a straight shutoff valve used to close off water supply during repairs.

Sump Pump - A sump pump is used in basements that flood often. The sump pump sits in a pit that accumulates the water, where it pushes the water outside the home.

T&P Valve - The T&P Valve or the Temperature and Pressure Relief Valve is used to safely release excess heat or pressure in a water tank.

Supply Line - A supply line is a metal or plastic line that carries water directly from the main line into a plumbing fixture.

Tailpiece - The tail piece is a pipe that runs between a fixture and trap.

Trap - The trap is a curved section of a drain line that prevents sewer odor from entering your home. All plumbing fixtures have a “P” trap, except for a toilet that has an “S” trap.

Trapway - The trapway connects the toilet bowl to a waste outlet. The size of the trapway, also known as the passageway, influences clogging.

Trip Lever - The trip lever is the flush handle and actuating arm on a toilet tank. The trip lever is attached to the flapper, which results in the toilet flushing. The trip lever can also refer to the drain in a tub.

Vent - The vent is a pipe that allows air into the drain system.

Vent Stack - The vent stack, also known as a stink pipe, releases gas and odors outside the home.

Water Hammer - The water hammer is a loud noise and vibration associated with pipes being turned on or off. The water hammer is caused by a sudden surge, or halt, of water in the pipes.