Sat, 25 May 2013 08:24:08 +0100 http://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=9353&Focus=151737#Comment_151737 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=9353&Focus=151737#Comment_151737 Mon, 16 Jul 2012 08:14:15 +0100 nbishara
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]]> http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=9353&Focus=151817#Comment_151817 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=9353&Focus=151817#Comment_151817 Mon, 16 Jul 2012 17:07:01 +0100 jms452
If you only have 5m of ducting I'd use the ridgid stuff with semi ridgid (or two 45 rigid bends) instead of the 90.

Telescopic tubes are also useful to fit rigid ducting well and quickly.
http://www.polypipe.com/cms//product-categories/900x600/150c47f213c845fc7218106e4c39c5b1jpg-20120203134408.jpg]]> http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=9353&Focus=151841#Comment_151841 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=9353&Focus=151841#Comment_151841 Mon, 16 Jul 2012 19:47:10 +0100 nbishara
Thanks again,

Tania]]> http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=9353&Focus=151860#Comment_151860 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=9353&Focus=151860#Comment_151860 Mon, 16 Jul 2012 21:14:18 +0100 jms452
I can see the temptation to save a grand or so by going flexi on a whole house MVHR but if you only need a few m seems like its worth doing it right! What does the installation instructions advise - good starting point.

In terms of pressure drops down ducting you can simply add these up for all the individal components - if you see p63 onwards of this doc you will get the idea (ignore the rest).
http://toolbox.polypipe.com/sites/default/files/system_and_prod_selector.pdf

These numbers should be fairly transferable between manufacturers and duct materials]]>