Hi All,
We've got a "colony upper" flat in Edinburgh with a converted loft; the bathroom is upstairs and has a part coombed ceiling. There is currently a small (4") fan connected to the light circuit; that feeds into flexible ducting (120mm) which travels laterally for around 2m and then vents, via a duct-tape-rich bodged joint, into a 3" plastic pipe which in turn goes up vertically through the roof. The toilet (downstairs) extractor fan also vents through the same pipe.
We're looking to replace this with an inline fan controlled by a humidistat and we're looking for a couple of pieces of advice. I think I may have been a bit enthusiastic in the choice of fan - Manrose 150mm inline axial, shifts 230m3/hr - although the advice on the ideal size of fan varies from 3-20 times room volume (about 12m3) per hour. So that's the first question: how much air do we need to shift (I know building regs talk about 15l/sec intermittent)? Have I completely overcooked it with the fan choice? Will it matter much (we're planning on putting vents in the foot of the door and the inlet will be in the ceiling)?
Second question is about venting the fan. Ideally, we should either vent to the eaves from ceiling inlet or mount the fan directly through the coombe to the roof - neither of these options are possible in our case (well, the latter one is, but is less desirable). Given that, we're planning on removing the current outlet and putting in a new one much closer to the fan itself. Can anyone give us any advice on the best way of achieving this? Specifically, it seems to be difficult to get fittings for vents that go up to 150mm diameter.
Cheers - Adam...