Trickle Vent Equivalent Area: Why Vent Length Misleads Homeowners and Installers
Trickle Vent Equivalent Area Is the Number That Decides Everything I’ve seen more ventilation problems caused by the wrong assumption about vent length than by bad hardware. A 400 mm vent looks substantial. A 500 mm vent looks even better. But neither tells you how much air actually gets through the unit, and that is where many retrofits go wrong. When existing windows need background ventilation, a surface-mounted retrofit option is often the most practical fix. Even then, the vent only solves the problem if its equivalent area matches the room’s requirement. Length gets the vent onto the frame. EA decides whether the room gets enough fresh air. ...