Easiest way to retro-fit an extractor fan in a bathroom?

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We have en-suite and family bathrooms on the south-west facing side of the house, which gets blasted by wind and rain coming over open fields so I'm not keen on making holes in the wall. Normally we open the window to dry the rooms after showering, which is effective and is silent.

However I've always been aware that the attic feels damp; it's well ventilated so there's no condensation but family effects stored there smell musty and feel a little damp. I'm sure most of this is shower steam getting past the bathroom ceiling lights, which are bathroom-type sealed halogen units. At this time of year with cold winds blasting across we are less inclined to open the window so I'm beginning to regret not having fitted fans when we refurbed the house, because these would deal with most of the moisture during and for a few minutes after showering. They would also create a low negative pressure in the rooms to prevent moist air from seeping past the ceiling lights.

(We cook in the ovens of an Aga so all cooking steam goes up the Aga flue and we have a woodburner in the lounge meaning that the house is generally well aired. Clothes are dried in the utility, outside the main body of the house.)

Could I fit extractors in the ceiling, feeding into curved ducts and out downwards through vents in the soffit boards? Does anybody make a long vent for this application, which could fit into the narrow board? I would be concerned about condensation collecting in the cold ducting and dripping back into the bathroom, though they would be buried under about 500mm of glasswool so that might not be too big a problem.
 
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No problems with your proposal at all - you'll find flexible ducting fine, but try to prevent it falling in loops....rather a gentle fall to the soffit if possible.
If the ceiling is plasterboard, I use one of those vicious Alpha cutters to get a neat hole.
If you are intending to put in a timed fan, you'll need two live supplies, but only the one if there's no timer.
Seriously, I would doubt if dampness is coming through your ceiling lamps!
John :)
 
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Not really sure why this is in the plumbing section, but hey ho.

Is the attic a proper attic room, or just a loft void?

Venting to the soffit is ok, but it's often tricky to get a route big enough through to the soffit to acommodate the ducting with out restricting air flow.

If the attic is an unheated space, then you should use insulated ducting to prevent the build up of condensation which can both damage the fan and stain the ceilings below.

If your lights are IP rated fittings and properly installed, then no moisture should be able to escape through them.

Whilst a 4" extractor fan is usually installed as standard in bathrooms, more often than not they are woefully inadequate to actually remove steam and properly ventilate the room.

You should use a proper fan calculator to determine what size fan you really require.

Here's one:
http://www.tlc-direct.co.uk/Technical/Ventilation/Ventilation4.html
 
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I installed an in-line ducted fan in the loft last year; a Vent Axia ACM100T. It is a 4 inch fan but it's mixed flow rather than axial and works very well.

Due to the design on the house, venting the exhaust through the soffits wasn't possible so I got a special tile fitted in the roof which is specifically for this sort of thing - the duct connects straight to the spigot. I used insulated ductwork following advise on here and the actual fan is mounted on a slightly raised section of the loft floor so the ductwork slopes downwards.

http://www.screwfix.com/p/vent-axia-acm100t-in-line-extractor-fan/53730

HTH
 
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It's an open loft void and yes, the soffits are quite narrow, hence my question about a long narrow vent.

Useful advice, thanks. I think I'll get to grips with it next summer when I get scaffolding up and replace the fascias.
 
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If it's an open loft, then get a vent tile fitted in place of one of your regular roof tiles directly above the fan.

This helps keep the ducting as short and straight as possible, which really increases the performance of the fan, and the warm moist air will naturally be drawn up the 'chimney' you've created improving the performance of the fan even further.
 
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