Week 32, Day 4:

• More general progress – electrical first-fix, plastering etc.
• Today’s featured topic is the ventilation ductwork – see below the photo for more details

Week 32, Day 4

The majority of the ventilation ducts are 80mm Lindab LFPE semi-rigid tubing which run from plenum chambers near the MVHR unit to the intake and extract vents in the various rooms. Since some of the rooms are quite large the air flow rates are also relatively large and necessitate multiple runs of the ducting per room, coming together where they attach to the room vents.

Twin ventilation ducts for a single extraction vent

The “semi-rigid” ducts are reasonably flexible and can normally be “cabled” through the joists. However, in some cases a tight bend is required and this is achieved with a metal elbow.

Metal elbow fitting for 80mm semi-rigid ventilation ducts

In a few places, it makes sense to run few metres of rigid metal ducting to a plenum chamber some distance away from the MVHR unit.

Plenum chamber for transition from rigid metal to semi-rigid plastic ventilation ducts

Ventilation ducts in second Bedroom ceiling

There are strict limits on the noise levels permitted from a ventilation installation (part of the Passivhaus standard) and despite using a high-quality unit some silencers are required.

Silencers for ventilation ducts

It can be difficult to get an accurate sense of scale from the photo, but those are full-size (215mm x 440mm) concrete blocks in the wall and the silencers are 1.25 metres high and 400mm diameter (for 200mm ducts). Fortunately they get installed in the Plant Room, where there is plenty of space for them.