Pneumatic HVAC Control Terms

Front

Two-Pipe Pneumatic Thermostat

Back

A control device used in HVAC systems to sense room temperature and modulate the flow of compressed air to actuators or valves. In a two-pipe configuration, one pipe supplies main air pressure, while the other serves as the branch line to control heating or cooling valves, allowing for seasonal changeover between heating and cooling modes.

Front

SCIM (Standard Cubic Inches per Minute)

Back

A unit of measurement for air consumption or flow rate in pneumatic HVAC systems. It quantifies the volume of compressed air used by controls like thermostats or controllers, ensuring efficient system design and operation without excessive air usage.

Front

Pneumatic Velocity Controller

Back

A device that regulates air flow velocity in ducts or variable air volume (VAV) boxes by sensing differential pressure and adjusting dampers or valves accordingly. It maintains consistent air distribution and energy efficiency in ventilation systems.

Front

Pneumatic Pressure Gauge

Back

An instrument that measures and displays the pressure of compressed air in pneumatic lines. It helps technicians monitor system performance, detect leaks, and ensure controls operate within safe pressure ranges, typically 0-30 psi.

Front

Air Compressor

Back

A machine that generates and supplies compressed air to power the entire pneumatic HVAC control system. It compresses ambient air to a pressure of around 20-30 psi, often including dryers and filters to provide clean, dry air for reliable operation of thermostats, actuators, and valves.

Front

Pneumatic Actuator

Back

A component that converts pneumatic pressure into mechanical motion to operate valves or dampers in HVAC systems. It responds to signals from thermostats or controllers to adjust airflow, water flow, or steam for temperature regulation.

Front

Pneumatic Relay

Back

A switching device that amplifies or redirects pneumatic signals in complex control sequences. It can reverse, average, or select signals from multiple sensors, enabling sophisticated control logic like high/low selection or sequencing in larger HVAC setups.

Front

Pneumatic Receiver-Controller

Back

A central device that receives input signals from sensors (e.g., temperature or pressure) and outputs proportional pneumatic signals to actuators. It often has air consumption rated in SCIM and is used for precise control in applications like zone temperature management.

Front

Pneumatic Pressure Regulator

Back

A valve that maintains a constant output pressure despite variations in input pressure or demand. In HVAC, it ensures stable air supply to controls, preventing fluctuations that could affect system performance.

Front

Pneumatic Flow Control Valve

Back

A valve that regulates the rate of air or fluid flow in response to pneumatic signals. It is commonly used in air handling units to balance airflow or modulate chilled/hot water flow for optimal HVAC efficiency.