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Water collecting in duct pipe from extractor fan in bathroom

Discussion in 'Plumbing and Central Heating' started by ax222s, 20 Feb 2021.

  1. HERTS P&D

    HERTS P&D

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    Who fixed it............Frank Spencer?

    Andy
     
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  3. ax222s

    ax222s

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    In a word 'Yes'!
     
  4. ax222s

    ax222s

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    Just reigniting this post.

    Im finding it really hard to find someone to do this job for me. Is this a job for a plumber do you think? Or a handyman?
     
  5. MJN

    MJN

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    If I were you I'd just start by replacing the current ducting with some insulated ducting - it's cheap, still flexible so easy drop-in replacement (it's a bit more self-supporting so actually a bit easier!) and tends to have a smoother bore because it can maintain its stretched out shape better so performs better. It tends to have around 25mm of insulation, which is fairly typical for ducting in unheated spaces, and given its strength can be easily insulated by throwing more loft insulation over the top without crushing it.
     
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  6. ax222s

    ax222s

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    Thats a good practical solution. Thanks.

    So just to confirm (unless its not already apparent, Im a complete DIY novice!!) this is what I need to get: https://www.screwfix.com/p/manrose-...55281954508&ds_rl=1249404&gclsrc=ds&gclsrc=ds

    I presume theyre all a standard size. How do I fit/secure it either end? (to the fan and to the roof exit).

    Perhaps - as been suggested in this thread - Id be better off hanging the exit end in the gap at the eaves rather than attaching it to the exit vent in the roof?
     
  7. MJN

    MJN

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    Yes, but I wouldn't buy it from screwfix at that price. How much do you need? If only 5m then you can get it here for £17.99 including delivery. You'd normally fix it in place with jubilee clips or similar (what's holding the current ducting in place?). Note that the length is fully-stretched, and that's also how you want it so as to make the inside wall as smooth as possible. Make gradual bends too if you can.

    Regarding exit termination I don't think it'd make much difference. You're trying to avoid the warm moist air condensing in the first place which, if successful, means it doesn't matter how it terminates as there should be nothing to drip out.

    For what it's worth our house had a similar setup to yours (basic ceiling fan, unheated loft and a roof terminal) but with the insulated ducting and there were no issues. I did at one point fit an inline fan (Manrose MF100T, £50) which really improved flow and reduced noise to practically zero so you might want to consider that. (I've now fitted a whole house MVHR system which is superb but that might be a step too far!)
     
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  8. MJN

    MJN

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    Just hold fire on ordering anything - I see the one I linked to is 'acoustic' which means it has small holes on the inner skin which you probably don't want if there's any risk of even a small amount of condensation forming. I'll keep searching but it looks like there's quite a shortage at the moment (maybe that's why the screwfix stuff is so expensive).
     
  9. MJN

    MJN

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    Thinking about this further, event he acoustic stuff must have a vapour barrier so I think it'd be okay (and more to the point I can't find any that don't claim to be acoustic!).
     
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  11. ax222s

    ax222s

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    Thanks @MJN - this is very useful.

    From memory it is attached using a jubilee clip, Ill need to check. I know what a jubilee clip looks like, but I havent fixed one before.

    I will probably need about 5m length. Can I cut it to size?

    (Im sure 'acoustic' will be fine. Whatever I fit will be a massive improvement over whats there now!)
     
  12. MJN

    MJN

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    Yes, it can be cut - the foil and insulation will cut with scissors but there's a wire spiralling around to keep its shape and that might need a snip with wire cutters (bending it back and forth with pliers would also work in a pinch!).

    Jubilee clips are fairly straightforward - you just use a screwdriver or socket to tighten/loosen them. There's a video here.
     
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  13. ax222s

    ax222s

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    Excellent - thankyou! I will post up pics once Ive finished and you can critique accordingly! :mrgreen:
     
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  14. ax222s

    ax222s

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    @MJN : Ive measured the length I need (annoyingly its just a bit further than 5 metres, so Ill need a 10 metre length! :mrgreen:). I was just about to buy some, but what size would I need? (102mm/127mm etc...) https://www.fastlec.co.uk/ventilati...-ducting-flexible-insulated-aluminium-ducting

    I wont bother buying jubilee clips because I presume I can reuse the ones there.

    Also, I found this if anyone else is having condensation issues: https://www.fastlec.co.uk/ventilation-ventilation-ducting-thermal-duct-insulation . Unfortunately its no good for me becuase I made holes in my duct to bleed out the water, but I would have used this had I not.
     
  15. MJN

    MJN

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    If you disconnect the duct at the fan end you can double-check the size - it looks like it's 100mm to me (note they are just notional sizes so you may find a few mm discrepancy in practice).
     
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  16. ax222s

    ax222s

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    Hmm, ok, Ive had a closer inspection. I fear what may initially seem like a simple job will spin-off into a much larger job! (quel surprise!) :cry:

    It looks like the original installers gaffer-taped one end to the exit in the roof. (unless they gaffer-taped over a jubilee clip). This in itself is not an issue


    IMG_0139.jpg


    ... however, the other end goes into the insulation hardboard flooring. So perhaps - to get at where the duct connects to the fan - I need to lift up that section of the flooring. Something which Im inclined not to attempt.


    IMG_0138.jpg

    Is it possible to connect some new insulated duct to the existing duct? Probably not. But if it were possible then I could leave the flooring in place. Bloody hell.
     
  17. MJN

    MJN

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    The fan will need dropping from below. Remember you've got a ceiling, gap then board - the ducting will be attached directly to the spigot on the fan.
     
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