2,400+ Definitions
HVAC GLOSSARY
Every HVAC term, acronym, and industry phrase — defined in plain English.
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…
Product Data
Product data is manufacturer-supplied technical information including specifications, performance ratings,…
Programmable Thermostat
A programmable thermostat automatically adjusts heating and cooling setpoints according…
Propane Furnace
A propane furnace is a heating appliance that burns propane…
Propane Water Heater
A propane water heater burns liquefied petroleum gas (propane) in…
Property Assessed Clean Energy
Property Assessed Clean Energy (PACE) is a financing mechanism that…
Proportional Balancing
Proportional balancing is a simplified hydronic balancing method that adjusts…
Proportional Control
Proportional control modulates a valve or damper position continuously based…
Propylene Glycol Solar
Propylene glycol solar fluid is a non-toxic heat transfer liquid…
PSC Motor
A PSC (Permanent Split Capacitor) motor is a single-phase induction…
Psychrometric Chart
The psychrometric chart is a graphical representation of air properties…
Psychrometrics
Psychrometrics is the science of the thermodynamic properties of moist…
PTAC Installation
PTAC (Packaged Terminal Air Conditioner) installation involves mounting a self-contained…
PUE
PUE (Power Usage Effectiveness) measures data center energy efficiency by…
Pull Down Time
Pull down time is the duration required for a refrigeration…
Pulley Alignment
Pulley alignment is the critical adjustment process that ensures driving…
Pump Laws
Pump Laws are specific applications of the Affinity Laws that…
Push to Connect Fitting
Push to connect fittings provide quick, tool-free connections for plastic…
PV Powered Heat Pump
A PV powered heat pump uses photovoltaic electricity generation to…
PV System
A PV system is a complete solar energy installation that…
PV Wire
PV wire is a single-conductor, UV-resistant cable specifically engineered for…
PVC Flue
A PVC flue is a plastic exhaust pipe made from…
PVC Pipe
PVC (polyvinyl chloride) pipe is a rigid plastic tubing commonly…
PWM Controller
A PWM (Pulse Width Modulation) controller is a basic solar…