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Mould in extractor fan ducting

Discussion in 'General DIY' started by kipper1066, 10 Jul 2021.

  1. kipper1066

    kipper1066

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    Hi,
    There's a mouldy smell in my shower room, and I think it may be coming from the extractor fan. I removed the cover and cleaned around the motor and blades, which were pretty black, but I couldn't reach into the ducting.
    First, I'd like to know if mould in extractor fan ducting is a thing that happens?
    And, second, what can I do about it?
    Many thanks for any advice!
     
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  3. foxhole

    foxhole

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    If fan isn’t used on every use the mould can settle.
     
  4. opps

    opps

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    Do you know what path the ducting takes?

    From what I have seen elsewhere, ducting that follows a long path in to a loft cavity should have a condensation trap that lets the moisture drip away.

    That said, if the fan is running, any smell from the ducting should not enter the room. Off hand, I can't recall ever seeing mould on a fan.
     
  5. kipper1066

    kipper1066

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    Mmmm, interesting. Thanks for the replies.

    It does go into the loft then out just beneath roof. But there is no condensation trap - so that may be the problem.

    Thanks again!
     
  6. JohnD

    JohnD

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    Do you have the flexible ducting, made of convoluted hose?

    It is very prone to trapping condensation (and fluff)

    firstly between the ridges, and then it tends to hang in loops with a pool at the bottom of each loop.

    and it drips out of joints

    post some pics please.

    if you can replace with rigid duct, you can perhaps have a long straight run, tilting slightly towards the exit so any water runs outside and drips out.

    you can have a short upright piece from the bathroom ceiling, the moving air will still be warm enough in the first piece to prevent the duct chilling it and causing condensation. You can also wrap the duct in insulation to keep it warmer, which will also reduce condensation. If it is insulated, the longer you run it, the warmer it will get, so start the fan before you turn on the shower, and use a run-on timer to carry on blowing after you have finished.

    p.s.
    also, as you have ducting in the loft, you can use a powerful inline fan, which is likely to shift the steam much faster than a typical bathroom fan, and is also quieter. Can you post some pics?
     
  7. kipper1066

    kipper1066

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    Yes, the ducting in ridged like you describe. I think that could be the problem.
    As for pics, there isn't really much to see - just an extractor fan in the shower ceiling.
    Many thanks!
     
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  9. JohnD

    JohnD

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    Pictures of the loft duct.
     
  10. kipper1066

    kipper1066

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    Okay... Here are three images: shower, loft, and outside. The pic from the loft is poor, but you can see the ridged ducting looping out under the roof. It's normally buried under loft insulation.

    Many thanks.
     

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  11. JohnD

    JohnD

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    ok, so it emerges through the eaves grille that is blocked with fluff and cobwebs. Perhaps your windowcleaner could reach it?

    I can't really see the duct, but I bet you could run a straight pieces, with an elbow to go through the eaves, having a slight fall towards the exit.

    The fan looks like a typical 100mm 80 cu.m/hr extractor

    You can get a more powerful one that you can put in the loft

    the Soler & Palau Silent 250 is very good

    for best sound muffling, mount it on a ply board, padded on both sides with rubber mat or carpet underlay, screwed to the joists with with washers under the screwheads resting on the padding.

    There are cheaper alternatives that are not as good.

    Assuming the electrical supply is from the lighting rose, you can easily connect the timed version.

    I think your old fan is one of these, noise level 41db

    the S&P is about three times the power, and 19 - 24db
    plus it will be in the loft, with a padded board, and fibreglass insulation between the board and the ceiling.
     
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  12. kipper1066

    kipper1066

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    Thank you very much, JohnD.

    I wish the guy who originally fitted my shower and extractor fan had had the knowledge and professionalism that you have!

    Who would you recommend I ask to replace the fan and ducting - an electrician or a plumber?
     
  13. JohnD

    JohnD

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    DIY

    Or an electrician

    By personal recommendation, not an advertising website
     
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