Meanings of commonly used HVAC control symbols

Outlined below are the most commonly used hvac control symbols and their meanings.

Click here to view easy-to-use compiled charts of these symbols.

pressure sensor

Measures pressure of gases or liquids.

VARIABLE SPEED DRIVE

VSD enables variable control of motor speed and torque so that hvac systems can run at optimum efficiency.

Flow switch

Flow switches trip pumps on or off to control fluid flow.

Air conditioning controller

An electronic module that controls the hvac system.

carbon monoxide sensor

Sensors used to measure and thereby limit carbon monoxide.

co2 sensor

Used to measure CO2 concentration in air and adjust ventilation system accordingly.

DIFFERENTIAL PRESSURE TRANSDUCER

DPTs measure pressure difference across a region and aid in hvac zones systems such as stairwell pressurization, lift pressurization ,etc.

BUILDING MANAGEMENT SYSTEM

BMS is a computer based system that monitors the equipment systems of a building.

Relative Humidity sensor

Measures relative humidity of air.

Velocity meter

Measures air velocity in ducts.

FLOW METER

Measures flow in ducts and pipes.

Top to bottom

side to side

side to bottom

Damper

Dampers are used to regulate airflow.

VAV Box

VAV boxes regulate air flow through a duct.

THERMAL Energy Meter

Thermal Energy Meters measure amount of energy content in chilled water liquid flow.

Heat Exchanger

Heat exchanger is a device that transfers thermal energy from one medium to another.

Click here to view the list of common HVAC equipment symbols

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Click here to view the list of common HVAC piping symbols

Click here to view easy-to-use compiled charts of all common HVAC symbols.

Meanings of commonly used HVAC piping symbols

Outlined below are the most commonly used hvac piping symbols and their meanings.

Click here to view easy-to-use compiled charts of these symbols.

CHILLED WATER SUPPLY

CHILLED WATER RETURN

HOT WATER SUPPLY

HOT WATER RETURN

COLD WATER SUPPLY

COLD WATER RETURN

REFRIGERANT LINE

MAKEUP WATER LINE

HUMIDIFICATION LINE

DRAIN PIPE

VENT PIPE

PRESSURE GAUGE

AUTOMATIC AIR VENT

TEST POINT

PIPE RISER/DROPPER

FLOW DIRECTION

FLEXIBLE PIPE CONNECTION

TEMPERATURE GAUGE

STRAINER

Click here to view the list of common HVAC equipment symbols

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Click here to view easy-to-use compiled charts of all common HVAC symbols.

Meanings of commonly used HVAC Ductwork symbols

Outlined below are the most commonly used hvac ductwork symbols and their meanings.

Click here to view easy-to-use compiled charts of these symbols.

Straight duct

Ducts are conduits or passages used in hvac systems to move air.

branch duct

In order to split air passage among spaces, branch ducts are used.

duct bend

In order to make smooth turns and avoid turbulence bend pieces are used in the air passage.

y-junction

3-way junction

junction

beveled junction

Such junctions are used when a part of the air from the main passage is diverted to a certain space.

miter bend

A miter bend(elbow) is made by mitering or bevel cutting two pipes or ducts usually to form a 90 degree turn.

Duct Transition

Used to reduce to effective diameter of a duct. Transitions are required to change the overall size or shape of a duct.

Duct offset Transition

Supply Ceiling Diffuser

Distributes conditioned air uniformly throughout the room. These are visible on the ceiling.

Return Ceiling Diffuser

Collects return air from the room. These are visible on the ceiling.

Flexible Connector

Flexible connectors are used as attachments between ducts and equipment in order to reduce noise and vibration.

VAV Box

Variable Air Volume(VAV) boxes maintain the temperature of a space by controlling the supply of conditioned air through the duct into the space.

Duct Damper

Duct dampers are control devices in ducts that function like butterfly valves to control airflow.

Linear Diffuser Supply/Return

Linear diffusers distribute air evenly throughout a space.

Floor Register

A register is a grille with air flow adjustment.

Air grilles

Air grilles are used to evenly distribute air in a space.

Duct Heater

Used to heat air flowing through a duct.

Flexible Connection

Used to reduce noise and vibration.

Louver Opening

Louver is a device used in hvac ventilation systems to allow air to pass through while keeping out dirt and debris.

New Ductwork

INSULATED DUCTWORK

Insulated ducts are used to reduce thermal energy loss and prevent condensation on ducts.

EXTERNALLY INSULATED DUCTWORK

Insulated ducts are used to reduce thermal energy loss and prevent condensation on ducts.

FIRE RATED DUCT SYMBOL

Fire resistant ducts help maintain compartmentalization and divert smoke.

volume control damper

Used to control volume of air passing through a duct.

fire damper

Fire dampers are fire protection devices used to prevent spread of fire through ducts.

flexible connection

duct spigot with butterfly damper

non return damper

Non return dampers ensure airflow in single direction

duct mounted attenuator

Used near AHUs/FAHUs to reduce transmission of noise.

Motorised damper/ motorised smoke & fire damper

Performs the same function as a regular damper but is motorised and can be controlled automatically.

circular flexible duct

DUCT RISER

Duct that rises vertically through a building or structure.

DUCT DROPPER

Duct that drops vertically through a building or structure.

duct acoustic lining

Duct acoustic liners are primarily used for sound absorption.

vertical duct section

circular diffuser

supply duct section

return duct section symbol

Click here to view the list of common HVAC equipment symbols

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Click here to view the list of common HVAC control symbols

Click here to view easy-to-use compiled charts of all common HVAC symbols.

Meanings of commonly used HVAC equipment symbols

Outlined below are the most commonly used hvac equipment symbols and their meanings.

Click here to view easy-to-use compiled charts of these symbols.

fcu

Fan Coil Unit is a device that heats or cools a space using a coil and a fan.

ahu

Air Handling Unit (AHU) is a device used to circulate air in an hvac system.

chiller

Chiller is a device that removes heat from a liquid by making use of the VCR cycle.

pump

In hvac systems pumps are used to pressurize and movie liquid along hydronic lines.

compressor

In hvac systems, the compressor compresses the refrigerant.

fan

Different types of fans are used in hvac systems. Each performs a different function.

cooling coil

Cooling coils remove heat from the air.

silencer

Silencers reduce airborne noise.

muffler

Mufflers in hvac systems reduce noise by dampening gas pulsations in compressor suction and discharge lines.

air filter

Air filter collects dust and debris while letting air pass through.

dx unit

A direct expansion air conditioning unit(DX unit), cools air using a refrigerant liquid.

dryer

The dryer in hvac systems absorb extra moisture.

condenser

The condenser is the component of the hvac system that removes heat from the refrigerant.

temperature sensor

cooling tower

Cooling towers in hvac systems remove heat from water that is pumped to it from the condenser.

solenoid valve

Solenoid valve is an electromechanical valve that can be used to turn refrigerant flow on and off.

gate valve

Gate valves are used to fully open or close flow.

globe valve

Globe valves can be used to regulate flow.

butterfly valve

Butterfly valves are used to regulate flow.

Check valve

Check valves ensure that flow occurs only in one direction.

Click here to view the list of common HVAC control symbols

Click here to view the list of common HVAC duct-work symbols

Click here to view the list of common HVAC piping symbols

Click here to view easy-to-use compiled charts of all common HVAC symbols.