Passive Ventilation

Roof Terminals

Ridge terminals are normally used for PSV systems. Where the house layout does not permit the use of a ridge terminal, two tile/slate terminals can be connected via a T junction within the roof space, where they then should be sited as high up the roof slope as possible.

Ducting

A separate 125mm duct is required for each extract. Uninsulated Flexible or Rigid Ducting may be used only within the heated parts of the house. Insulated Flexible Ducting must be used in unheated spaces, including the roof space, to prevent condensation forming within the duct and running back into the building.

Ductwork should take the shortest route with the minimum number of bends and offsets. Any offsets must be within 45° of vertical. All flexible ducting must be kept as taut as possible and be supported throughout. All connections must be sealed with tape and clamped.

Air Extracts

One extract is required in the kitchen, and one in the bathroom (and also utility room, separate wc where necessary). Site extracts within 1m of cooker (where applicable) but not directly above it, away from doors or windows and direct sources of dry heat. Extracts should preferably be in the ceiling, but an A162 can be located on a wall, at least 1.8m above floor level, connected to Flat Channel Ducting. Passive extract grilles may also be needed in a utility room and separate WC if necessary.

Air Inlets

Wall or window inlets are required in each habitable room; living room, dining room, bedrooms, and should be minimum 1.8m above floor level.

Humidity Sensitive Window Inlet with trickle facility, fitted to a slot in the window head.

Overglass Vent Bar, supplied fitted with Humidity Sensitive Window Inlet and installed above the glass within the window frame.

External Canopy Grille provides weather and insect protection for window inlets.

Flat Channel Ducting, designed for snug fitting into corners, or within the voids of stud partition wall (size 204 x 60mm). Not for use in the roof space. The circular adaptor allows connection to circular ducting. All connections must be taped.

Humidity Sensitive Extract without spigot must be used with flat channel ducting.