HVAC humidifier symbol

A duct section with rising droplets.

Also known as: Steam humidifier symbol, Moisture injection symbol

Engineering & technicalStandard profile

Meanings

The services drawing symbol for a humidifier adding moisture to the supply air.

Officially standardisedVerified fact
Marks a humidifier adding moisture to supply air on a services drawing.
Contexts: Technical drawing
Officially standardisedVerified fact
Draws what is added rather than the device adding it, which is the opposite choice from the coil symbols standing beside it in the same unit.
Contexts: Technical drawing

A section of duct containing several small drops or a set of short rising strokes.

Current useHigh confidence: High confidence because the current use is defined by a current official standard, but only a single source has been found so far.
IdentityHigh confidence: High confidence because the identity is defined by a current official standard, but only a single source has been found so far.
Historical originLow confidence: Low confidence because the historical origin is documented in encyclopedic references, but only a single source has been found so far, but early or supporting evidence is limited, but the regional or cultural match to this specific claim is not precise.
Visual matchModerate confidence: Moderate confidence because the visual match is documented in encyclopedic references, but only a single source has been found so far.

ASHRAE graphical symbols for heating, ventilating and air conditioning
American Society of Heating, Refrigerating and Air-Conditioning Engineers · retrieved 2026-08-25
The principal standard for HVAC drawing symbols. Cited for a symbol's identity and what it represents on a services drawing. Not cited for the design or sizing of any installation, and no record is a specification.

Last reviewed 2026-08-25

Meanings

The services drawing symbol for a humidifier adding moisture to the supply air.

Officially standardisedVerified fact

Marks a humidifier adding moisture to supply air on a services drawing.

Officially standardisedVerified fact

Draws what is added rather than the device adding it, which is the opposite choice from the coil symbols standing beside it in the same unit.

Confidence

Current useHigh confidence: High confidence because the current use is defined by a current official standard, but only a single source has been found so far.
IdentityHigh confidence: High confidence because the identity is defined by a current official standard, but only a single source has been found so far.
Historical originLow confidence: Low confidence because the historical origin is documented in encyclopedic references, but only a single source has been found so far, but early or supporting evidence is limited, but the regional or cultural match to this specific claim is not precise.
Visual matchModerate confidence: Moderate confidence because the visual match is documented in encyclopedic references, but only a single source has been found so far.

Sources

ASHRAE graphical symbols for heating, ventilating and air conditioning
American Society of Heating, Refrigerating and Air-Conditioning Engineers · retrieved 2026-08-25
The principal standard for HVAC drawing symbols. Cited for a symbol's identity and what it represents on a services drawing. Not cited for the design or sizing of any installation, and no record is a specification.

Last reviewed 2026-08-25