inline fan/ condensation trap/ ducting /botch job

Discussion in 'Electricians' Talk' started by bunhead, Nov 30, 2017.

  1. bunhead

    bunhead Member

    I need some advice please.

    I had an in-line loft fan fan installed to help with condensation in the shower room.

    Unfortunately the guy who did the job rerouted the system wrongly.

    I was later told that the fan is in the wrong place of the the junction!

    1 can anyone recommend where the fan should be?

    2 I was also told that the condensation trap is not doing anything, that its in the wrong place! (its the black small circular bit in the vertical pipe nearest to the camera)

    That the water will run into the fan, and that a dark water stain is already is visible by the fan on the floor where water has leaked

    Looking at the pictures is this true?

    Also now the smells from the kitchen go into the bathroom as although he installed a back draft shutter, the pipe duct leading downwards into roof floor into the bathroom ceiling is too short to install the backdraft shutter

    so now every time the kitchen exhaust is on it feels like you are having your hair blow dried and the smells come from the kitchen into the bathroom

    3The other person coming in to correct the job (he to just separate the kitchen and the bathroom duct so that they dont share the same duct, and have them join just before they exit the roof)
    He however said he will only work with aluminium spiral duct which has ridges in, he doesn’t work with plastic he says.

    4 I am concerned that the warm wet air collect in the ridges and when it cools just sit there,and so wont do its job properly

    (the vertical pipe by the wall is the soil stack. The one where the fan is attached is for the toilet and kitchen)

    Please can you give me your advice or opinions?:(

    Attached Files:

  2. DIYDave.

    DIYDave. Well-Known Member

    Can’t comment on all the issues as I’m diy, but have run similiar in my own loft (1 fan only though)

    And in no particular order -

    The condensation trap isn’t the black circular piece you mention - that’s just a coupling to join 2 bits pipe together

    The trap is immediately after the bend in the floor, covered in tape but you can see a raised grey ridge, with the white overflow pipe attached - that’s your condensation trap. It’s in the right place, as near to the base of a vertical pipe as possible (and it is)

    If uv got a well ventilated loft that’s cold in winter, any warm moist air trying to escape may well condense on its way out. More so in a cold pipe and more so when traveling vertically up to the roof

    Smooth ducting is better than ridged as less resistance to air flow but, the 110mm pipe does get cold and the air inside it also

    The plastic flexi duct is paper thin and although used in millions of houses, I guess the ali stuff is a lot better, although more expensive. I think that it may also be available with an insulating layer attached ?

    The soil pipes can be insulated with either foil blanket or the fluffy stuff on a roll and gaffer tape, should minimise condensation and increase volume of moist air that escapes

    Does look like a lot of water staining around base of fan - needs to be looked into for sure. If water finds its way into fan will soon kill it and may trip the power

    That’s it for now
  3. Hi Bunnie.

    The first vent inlet to the right of the fan and after the two bends is that the kitchen or bathroom - I'm guessing bathroom?

    The issue could be as simple as this - the Tee piece should be reversed so that the the side entrance is sloping towards the pump.

    Try that first.
  4. What do you think of that Tee piece?

    Can you imagine the fan extracting air from the furthest inlet (under the eaves) and some of that air becomes diverted down that Tee piece due to the slope direction?
  5. Having said that, the second guys plan of taking each inlet ducting separately as close to the final vent outlet as possible before then inserting the fanm does make sense.

    I personally wouldn't be concerned by the use of ali ducting - the tiny ridges will have, I think, little averse effect.

    And as Dave says, you can add insulation to it which should help a bit.

    What I would suggest also is, have a timer on the fan so it continues running for a good 5 minutes after the room is vacated - the resulting air current is the single best thing to clear away any condensation.

    Do I take it that the single fan is controlled by two switches, one in each room?
  6. bunhead

    bunhead Member

    Thank you Dave and Devils Advocate!!

    I will get the guy to do 2 separate ducts but will also ask him to do as you suggest Devils advocate, that the T- piece should be reversed so that the the side entrance is sloping towards the pump.

    The inline loft fan an is actually for the bathroom only. i was having a lot of condensation problems so i may have gone a bit for overkill.I have been told it is maybe a bit too strong. Its a 6 inch mixed flow fan that extracts 565m3/hr 565m
    - Max Flow Rate: 157 L/s
    I think its like when you have a problem like a veruca-you then tend to go for the most powerful sounding medication like 'veruca bazooka'!
    This is the fan i got:

    The kitchen has hood above the cooker and you turn that switch on and the vent hood then works .

    The fan in the bathroom is connected to the light switch.
  7. bunhead

    bunhead Member

    this is what the first guy did, but he used an uninsulated ducting

    Attached Files:

  8. bunhead

    bunhead Member

    (aluminium flexiduct)which when I mentioned to my friend she told me she had a lot of problems in the past with water staying in it and leaking
  9. bunhead

    bunhead Member

    Devils advocate,

    Looking at the t junction ,at the risk of sounding a bit thick again, how can one reverse it, as it seems to me that that it wont be feeding all the pipes?
  10. What is your current setup, Bun - as in the first photos or as in post #7?

    But, jeepers, both are blessed with issues.

    Which inlet is the kitchen and which the bathroom?

    When you look at these layouts, Bun, can you see where issues could arise?

    In the first pic, when you consider that the air is meant to be heading in the direction of the fan, can you see how the Tee's swept side bend is facing the wrong way? Turning it around isn;t totally straight-forward as the fitting's ends are different - one is male and t'other female. However, the 'male' end does have a 'union' slipped over it, so that turns the male in to a female. But some juggling of the pipe will still be required.
  11. JP.

    JP. Screwfix Select

    Is that your missus in your profile picture DA?
  12. bunhead

    bunhead Member

    Your post did make me laugh! :D
    First time I have been able to since this headache! Male, female ,union etc

    The setup I have now is the first picture with all the rigid ducting...
  13. Sparkielev

    Sparkielev Well-Known Member

    Gina Millar
  14. bunhead

    bunhead Member

    when you say 'swept sidebend' is that the rough s shape just before the t junction?
  15. NOOOOOO!

    This is a Tee: D191.jpg

    See how the side connection joins the 'main' part via a swept bend? Yes? Cool. That is obviously the direction the fluid should be flowing. Now look at how it has been installed in your setup.

    At least the way your system is now is an improvement on the first one in post #7. Jeepers - just visualise the air flow from that powerful fan hitting that Tee piece - half would go up the pipe as it should, and the rest would head off to the other room. Nuts, man.

    Anyhoo, for the third bludy time, which inlet is the kitchen and which the bathroom?
  16. bunhead

    bunhead Member


    Well, I now understand a lot more!

    So where the T piece goes down is where the bathroom is. The the vertical end of the T piece goes directly through the bathroom ceiling over the shower.

    In picture 1 of post 1,kitchen duct is at the very end of the orange pipe , where the shiny grey pipe is
  17. As I thought in post #3 - the bathroom is the one closest to the fan.

    You will now see why the smells from the kitchen come down in to that bathroom? The kitchen extractor pushes the air along its duct, and air - like water and electricity - will take the easiest paths. Hmm, shall I go all that long way through the other fan and up through the roof, or shall I just pop down in to the bathroom.

    And that isn't helped by that Tee almost encouraging the air to sweep down that bend. Nuts, man.

    But, simply turning that Tee around won;t cure it - the kitchen will still blow down in to the bathroom (but that's better than your first setup which would have blown the bathroom in to the kitchen...)

    If you really must stick with a single outlet vent through the roof (no chance of adding another?), then I would ask for guarantees from the installer that their plan will work before engaging them. I don't see an easy solution when two fans blow down tubes which join together at some point. Even back-flaps aren't air tight, so some foulness will still get past.

    Even if the join is made as close to the outlet vent as possible - which will certainly help - it's still no guarantee.
  18. Sparkielev

    Sparkielev Well-Known Member

    I would install another fan for the kitchen and T it off after the bathroom
  19. bunhead

    bunhead Member

    if adding another would be the best solution then i would go for it. However the people i asked did not want to go onto the roof, saying things about that they cant get cherry pickers etc.

    Its very strange... the very original layout before i had any inline fan isntalled, also had the shared duct .
    The exit for the old fan (which was not an inline fan and 20 years old and not very powerful) was on the left, and cant be seen on the picture as its too far along.
    ( the Y junction is a new thing) I wanted the vent outlet to be above the shower so it would be the most effective. The old fan was in the corner of the bathroom.

    So with the original set up the first exit the air from the old bathroom fan would would come across, was the pipe leading up to the roof. The first exit for the kitchen pipe was the vertical pipe leading up to the roof .
    I never had any smells
  20. bunhead

    bunhead Member

    So it seems that asking the guy to put the grid above the shower caused this problem with the awkward t junction and air wanting to go down it as its the easiest path? As there never was a t junction before.

    The exit from the very original layout before i had ANY work done on the left which cant be seen on the picture. should i get the t junction hole closed over and the fan exit installed in the corner of the room where it used to be?

    Sparkliev... yes Someone else i had over to look at it also mentioned getting a another fan ... :0(
    its getting v expensive

    I wish i never had this inline fan installed, at least the old system didnt leak or cause smells

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