Installation, validation and maintenance

Condensate Drainage

冷凝水排放

Condensate drainage is the collection and removal of liquid water produced by a cooling-and-dehumidifying surface or related equipment.

Aliases: condensate removal, dehumidifier drainage

QUANTITY, SYMBOL AND UNIT

Quantity / objectCondensate drainage

UnitNot applicable

Definition

Condensate drainage is the collection and removal of liquid water produced by a cooling-and-dehumidifying surface or related equipment.

A complete drainage path normally includes runoff from the coil, a collection pan or outlet, piping or pumping, overflow protection and an approved disposal point. Poor drainage can cause re-evaporation, leakage, biological fouling, corrosion or equipment shutdown.

Relations and distinctions

Drainage and dehumidification capacity

Capacity states the rate of water removed from air under defined conditions; drainage determines whether the resulting liquid is reliably carried away.

Condensate and leakage water

Condensate forms from water vapour on a cold surface. Rain, wash water and plumbing leaks are separate sources even if they reach the same area.

Engineering meaning

Check drain elevation, continuous fall, trap or pump requirements, freezing exposure and accessible cleaning points.
Provide overflow detection or secondary containment where a blockage could damage equipment or a finished area.

Common misconceptions

MisconceptionIf a dehumidifier removes water from the air, the condensate will always drain by itself.

Accurate explanationReliable removal depends on pressure, elevation, slope, outlet design, blockage control and the selected disposal route.

Application boundaries

Trap and vent requirements depend on the pressure at the drain connection and the applicable installation rules.
The glossary definition does not approve discharge to any particular sewer, exterior or process-water destination.

Supporting sources

ASHRAE / SRC-ASHRAE-S20-CH25

ASHRAE Handbook - HVAC Systems and Equipment, Chapter 25: Mechanical Dehumidifiers and Related Components ↗

2020 SI edition / Chapter 25, condensate runoff, direct gravity drainage, overflow protection and drain routing
Supports: Mechanical dehumidification produces condensate that must be collected and removed; Coil arrangement affects runoff and re-evaporation; Drain routing, overflow protection and disposal provisions are installation concerns

Maintenance record