2,400+ Definitions

HVAC GLOSSARY

Every HVAC term, acronym, and industry phrase — defined in plain English.

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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 Loop Fluid
A food-grade antifreeze solution commonly used in geothermal closed loops…
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…
Psychrometer
An instrument consisting of two thermometers, one dry-bulb and one…
Psychrometric Chart
The psychrometric chart is a graphical representation of air properties…
Psychrometric Constant
A coefficient in the psychrometer equation that relates wet-bulb depression…
Psychrometric Process Line
A line drawn on a psychrometric chart connecting the entering…
Psychrometric Wet Depression
The difference in temperature between the dry-bulb and wet-bulb readings…
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…
Pull-Down Load
The initial high refrigeration demand required to reduce a warm…
Pulley Alignment
Pulley alignment is the critical adjustment process that ensures driving…
Pulse Width Modulation
The technique used in VFD output stages where the width…
Pump Curve
A manufacturer-supplied graph showing the relationship between a pump’s flow…
Pump Laws
Pump Laws are specific applications of the Affinity Laws that…
Pump-Down Cycle
An operational sequence in which the compressor draws refrigerant out…
Pump-Down Procedure
A service technique in which the compressor is run while…
Pumpdown
A service procedure in mini-split and VRF systems where the…
Push to Connect Fitting
Push to connect fittings provide quick, tool-free connections for plastic…
Push-Pull Recovery
A recovery technique in which the recovery machine pulls vapor…
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…