Position of in-line shower extract fan and ducting

Discussion in 'Plumbers' Talk' started by diymostthings, Jul 19, 2017.

  1. diymostthings

    diymostthings Well-Known Member

    I have got very restricted access across the floor of our loft due to a low headroom above the new shower position.

    Realistically, I will have to mount the fan about 1.2 meters away from the extract shower spigot (where there is more headroom) but then double back with the outlet flexible pipework (past the shower spigot again!) and out through the external wall beyond.

    So far so good but...

    There is very limited opportunity to floor mount the fan as there is a gas pipe (I don't want to move) bang in the way. So:

    Would it be OK to mount the fan on a small "aerial platform" hanging from the roof rafters?

    I thougth this would have the added advantage of giving a downward slope to the extract pipe to the outside and also might be less vibration/noise coming through the shower ceiling?

    It sounds all wrong, but I'm having a job coming up with a good objection - so thougth I would ask the experts.

    Thanks for any comments (sorry its a longish post).
     
  2. The Teach

    The Teach Well-Known Member

    Yes its do able,
    but consider a fan that will deal with the length of ducting,for example this fan will do up to 7m of ducting but i always half what the makers says to be on the safe side. https://www.tlc-direct.co.uk/Produc...MIqZeFwvOV1QIVwantCh3IDwf1EAQYAyABEgLvYvD_BwE
    SF do a similar fan but may fail to mention the duct length and other tech stuff.

    Keep the duct as short possible,secured with no sagging,ensure the fan is level/secured and in a ventilated area,all straight forward stuff.
    Condensation will occur in the duct so the slope down will be help to drain outside.
    If vibration transfer is a problem then this mat or similar will help http://www.screwfix.com/p/salamande...gclsrc=aw.ds&dclid=CPGa16f5ldUCFaKP7QodtTYLnw

    TT
     
  3. diymostthings

    diymostthings Well-Known Member

    Thanks for that TT - looks like my idea could be OK. The fan is a Manrose MF100T:
    http://www.screwfix.com/p/manrose-mf100-100mm-mixed-flow-fan/26867
    with a max. flow rate of 245m3/hour, but as you say no mention of permissable duct length. I hope that my run of ducting (allowing for "gentle" bends) would be a maximum of 5.5metres so this should be OK.

    One thing I noticed about the one-way butterfly valve I have to use - this goes downstream of the fan on the exit side - but if there is a downward slope on the duct as intended, the flaps of the valve are held open (through gravity). It would seen that they would only close naturally with the exit side duct sloping upwards, which of course is not wanted.

    Very grateful for your comment so I will procede with confidence!
     
  4. The Teach

    The Teach Well-Known Member

    An alternative to the duct butterfly is a gravity grill

    google Extractor Fan Wall Grille 4" 100mm Ducting Gravity Flap
     
  5. diymostthings

    diymostthings Well-Known Member

    Thanks again TT - well I was aware of these - but my son had them on his extract system and they were forever clattering in the wind. We changed them for the fixed grill (with insect mesh I think) and left out the butterfly valve.
     

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