2,400+ Definitions
HVAC GLOSSARY
Every HVAC term, acronym, and industry phrase — defined in plain English.
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…
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…
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…
Power Factor
Power factor is the ratio of real power to apparent…
Power Factor Correction
Power factor correction is the installation of capacitors or other…
Power Meter
A power meter is an electronic instrument that measures electrical…
Power Optimizer
A power optimizer is a device installed on individual solar…
Power Purchase Agreement
A Power Purchase Agreement (PPA) is a contractual arrangement in…
Power Quality
Power quality refers to the consistency and purity of electrical…
Power Usage Effectiveness
Power Usage Effectiveness (PUE) is a metric measuring the ratio…
Power Vent
A power vent uses an electric blower or fan to…
Powerwall
Powerwall is a lithium-ion home battery system manufactured by Tesla…
PPD
PPD (Predicted Percentage Dissatisfied) quantifies the percentage of occupants expected…
Pre Cool
Pre Cool is the practice of cooling a building below…
Pre Cool Coil
A pre-cool coil removes heat from outdoor air before it…
Pre Heat
Pre Heat is the practice of heating a building above…
Precision Cooling
Precision cooling, also known as close control cooling, refers to…
Predicted Mean Vote
Predicted Mean Vote (PMV) is a thermal comfort index that…
Predicted Percentage Dissatisfied
Predicted Percentage Dissatisfied (PPD) is a metric that quantifies the…
Predictive Maintenance
Predictive maintenance uses performance data and trend analysis to forecast…
Press Fit Fitting
Press fit fittings are mechanical connectors that join copper or…
Pressure Balancing Damper
A pressure balancing damper is a manually or automatically adjustable…
Pressure Data Logger
A pressure data logger automatically records air pressure, duct pressure,…
Pressure Dependent VAV
A Pressure Dependent Variable Air Volume (VAV) system is a…
Pressure Drop
Pressure drop is the reduction in air pressure as it…
Pressure Enthalpy Diagram
A pressure-enthalpy diagram, commonly called a P-H diagram, plots refrigerant…
Pressure Independent VAV
A Pressure Independent Variable Air Volume (PI-VAV) box is a…
Pressure Reducing Valve
A pressure reducing valve automatically limits system water pressure to…
Pressure Reducing Valve Plumbing
A pressure reducing valve (PRV) automatically decreases high incoming water…
Pressure Relief Valve
A pressure relief valve (PRV) is a spring-loaded safety device…
Pressure Sensor
A pressure sensor measures static, dynamic, or differential pressure in…
Pressure Switch
A pressure switch is a safety control device that opens…
Pressure Testing
Pressure testing is a diagnostic and quality assurance procedure in…
Pressure Testing Refrigerant
Pressure testing refrigerant involves applying nitrogen gas to an HVAC…
Preventive Maintenance
Preventive maintenance refers to scheduled service activities performed on HVAC…
Primary Control
A primary control is a safety device used in combustion-based…
Primary Secondary Loop
A primary secondary loop divides a hydronic system into two…
Process Exhaust
Process exhaust refers to contaminated air, vapors, and particulates removed…