Hi all,

After a lot of indecision about how to deal with my damp & mould, I've bought a Nuaire 365 positive input ventilation unit. If you don't know it, essentially it takes air from the loft and puts it in the house through one central point above the stairs. When the loft is too hot (which seems inconcievable right now, but it does happen normally), it takes air from the North facing roof.

I have a small loft, so a small ducting run. I need about a metre of 200mm, with one 90 degree bend into the distributor vent, and probably about 3 metres of 150 mm to the roof vent.

My question is: flexi ducting is cheaper and easier, but over that length of run, how much will it affect the airflow and therefore increase the energy usage of the fan? I envisage running the unit all year because even in summer (especially right now), opening the windows makes very little difference to the internal humidity.

My other question, for the same reason, is what sort of roof vent to use to maximise ease of air flow and reduce energy usage on the fan? I don't want to go through soffits or wall because I intend to EWI. I've got Ludlow Major interlocking tiles and I can easily get another vent tile, with a 100mm adapter tube. I'll then have to step this up to 150mm tubing to the fan, but somebody advised me that I'd be better off with a mushroom type vent.

Any thoughts would be very welcome as I'm desperate to get this in before I get another chest infection ;-(

Thanks,

Tania

Thanks very much for the advice; I didn't know telescopic tubing existed, so that's really helpful. Do you think it'll make a difference then, if i was lax and went for flexi pipe with a roof vent? I just know nothing about ventilation so can't judge.

Thanks again,

Tania