Extractor fan steam condensing in loft duct

woj101

My flat has an extractor fan serving the bathroom. The bathroom has no windows and so is fairly reliant on the extractor fan removing the majority of steam created when the shower's in use etc.

The duct for the fan runs up into the loft and right across to the opposite end and corner of the flat and is probably about 15m in length. The middle of the duct is rigid plastic piping but at either end there is white flexible ducting.

Unfortunately the design tends to lead to quite alot of steam condensing in the first section of ducting, causing it to sag and rest on the insulation. Over time it fills and requires emptying, but worse still is that the lining has degraded, resulting in the condensed steam dripping out, through the insulation and into the bathroom ceiling.

Any suggestions as to the best way to resolve this problem? Re-routing the ducting to a closer outlet isn't really an option 'cos the flat is leasehold and external changes aren't desirable/cheap.

- Would trying to insulate the flexible ducting have much impact on reducing condensation?

- Do I need a more powerful extractor fan (if available)?

I'm sure others must have had similar problems so hopefully there's a success story out there somewhere...

Thanks very much for reading/considering.

olias

Any possibility with replacing the flexible ducting with rigid for the whole length, and making sure it has a 'fall' to it so that any condensation runs out? Have you made enquiries as to routing it to a closer external wall. the only change to any outside appearance would be a small (approx 8") vent cover on the wall. These can be brown, black or white, to blend in with the wall covering. I can't see there would be any complaints as it needs sorting as clearly the current design is flawed, and the flaw has the potential to cause damage to the fabric of the building.

Olias

ic

I'm no expert, but my own inclination would be to replace the damaged sections of pipework and then lag the lot, perhaps either burying under the existing insulation or getting another roll of insulation to go on top/tucked around the pipe. Also I'd look at perhaps a more powerful centrifugal fan (if the fan you have now is an axial fan it won't be up to the job of shifting the air that distance). Also ensure that it has a run-on timer so it continues to run after the light has been switched off. This should means that it doesn't just stop with damp air still in the pipe.

phill99

15m seems an awful long way for a standard 4" bathroom to push vapour. I'll be surprised if any moisture is actually getting out in to the atmosphere.

You need a different fam. You need an 'in-line' fan which is a fan that sits inj the loft, half way between the grill in the bathroom and the outside vent. They are a stronger motor than a standard flush mounted bathroom fan.

ormus

as above. i doubt any water vapour is getting outside at all.
a better fan. rigid pipe. insulation. and a proper fall to outside.

savemoney

I agree with last two posters sounds like you fan isnt up to the job or teher is a blockage somewhere more likely the fan

woj101

Thank you all for your replies so far, plenty to consider there.

Given that the building was built in 2005 do you think the construction company should bear any responsibility for putting right the design?

phill99

woj101 wrote: »

Given that the building was built in 2005 do you think the construction company should bear any responsibility for putting right the design?

Highly unlikely. You probably just need to take it on the chin and deal with the problem.

Even if there is a 10 year NHBC warranty in place, the 10 years only applies to certain elements such as the superstructure. Services are, I think, restricted to 2 years.

ormus

the house has to fall down, before the NHBC warranty kicks in.

even then, they might have a get out clause.

muckybutt

Had this problem in council houses ive worked on in the past, what we did was to put a small piece of solid pipe onto the back of the fan so as to allow sufficent fall on the other solid pipe to the outside. On the solid bit from the fan at the top fit one of these http://www.tlc-direct.co.uk/Products/BGCT.html?source=froogle a condensation trap ( also need a piece ov overflow pipe to the outside ) from the top of the trap fit a solid bend to the outside section of some insulated flexible http://www.tlc-direct.co.uk/Products/FDAD4.html that should cure ya problems.