2,400+ Definitions
HVAC GLOSSARY
Every HVAC term, acronym, and industry phrase — defined in plain English.
Pilot Light
A pilot light is a small, continuously burning flame that…
Pipe Anchor
A pipe anchor is a rigid fastening device that locks…
Pipe Freeze Protection
Pipe freeze protection encompasses strategies and materials used to prevent…
Pipe Friction Loss
Pipe friction loss describes the pressure decrease caused by friction…
Pipe Guide
A pipe guide is a low-friction device that allows controlled…
Pipe Hanger
A pipe hanger is a support device that suspends pipe…
Pipe Heat Trace
Pipe heat trace is an electric heating system installed along…
Pipe Installation
Pipe installation involves placing copper, PVC, or polyethylene tubing for…
Pipe Insulation
Pipe insulation is a protective covering applied to hot or…
Pipe Length Equivalent
The total effective refrigerant pipe length in a VRF system…
Pipe Pressure Drop
Pipe pressure drop is the reduction in pressure that occurs…
Pipe Schedule
A Pipe Schedule is a detailed table specifying all piping…
Pipe Sizing
Pipe sizing is the process of selecting appropriate pipe diameters…
Pipe Slope
Pipe slope is the intentional grade or tilt applied to…
Pipe Support
A pipe support is a structural element that bears pipe…
Pipe Velocity
Pipe velocity measures the speed at which fluid flows through…
Piping System Design
Piping System Design involves sizing and routing water or refrigerant…
Pitot Traverse
A method of measuring volumetric airflow in a duct by…
Pitot Tube
A probe inserted into an airstream or duct that senses…
Pitot Tube Traverse
A pitot tube traverse is a method for measuring air…
Plate Freezer
A refrigeration device that freezes product by pressing it between…
Plate Heat Exchanger
A plate heat exchanger consists of thin metal plates stacked…
Plate-and-Frame Heat Exchanger
A compact heat exchanger using thin corrugated metal plates clamped…
Pleated Filter
Pleated filters feature accordion-like folds in the filter media that…
Plenum
A plenum is a chamber or box used to distribute…
Plenum Fan
A centrifugal fan with no scroll housing used in plenum-return…
Plenum Pressure
The static pressure maintained inside a supply or return plenum,…
Plenum Rated
Plenum rated refers to materials that meet strict fire safety…
Plenum Space
Plenum space is the cavity or chamber above a suspended…
PM 2.5
PM2.5 refers to particulate matter with a diameter of 2.5…
PMV
PMV (Predicted Mean Vote) is a numerical index that predicts…
Pneumatic Actuator
A pneumatic actuator uses compressed air pressure (typically 15-25 PSI)…
Point of Use Water Heater
A point of use water heater is a compact unit…
Points List
A Points List is a comprehensive inventory of all controllable…
Polycrystalline Solar Panel
A polycrystalline solar panel is manufactured from multiple silicon crystals…
Polyester Filter
Polyester filters utilize synthetic polyester fibers as the primary media…
Polytropic Compression
Polytropic compression is a more realistic refrigerant compression model incorporating…
Pond or Lake Loop
A geothermal closed-loop configuration where coiled piping is submerged in…
Pool Dehumidification
Pool dehumidification is the process of removing excess moisture from…
Pool Heating
Pool heating is the process of raising and maintaining swimming…
Pool Solar Panel
A pool solar panel is an individual collector module that…
Positive Pressure Room
A positive pressure room maintains air pressure higher than adjacent…
Positive Temperature Coefficient Thermistor
A solid-state starting device whose resistance increases sharply with temperature,…
Post-purge
A continued blower operation period after the gas valve closes…
Potassium Permanganate
Potassium permanganate (KMnO₄) is an oxidizing chemical compound used in…
Potential Relay
A potential relay is an electromagnetic switching device that removes…
Pounds per Square Inch
Pounds per Square Inch (PSI) is a unit of pressure…
Power Burner
A power burner is a gas burner equipped with a…