Two extraction fans in one en suite shower room

Discussion in 'Electricians' Talk' started by aiwnjoo, Nov 10, 2018.

  1. aiwnjoo

    aiwnjoo New Member

    Hello everyone, ill tell you the situation first and then the question :)

    We live in a newbuild and have an en suite bathroom that has an extraction fan which comes on with the light, no over timer though because of buildings reg i believe.

    The bathroom is quite small, there is a walk in shower, toilet and sink and it has a window and radiator.

    The extractor fan is strangely fitted about a 6ft away from the shower, the windows is the nearest point to the shower so because the walls are cold, whenever we take a shower the steam causes streaks on the walls so im forever wiping them down, if we close the windows it does it more so we leave the window ajar and the door open into the bedroom and this helps a bit.

    The extractor fan works, the builders have been out and checked everything (placing a piece of toilet paper under then fan to see if it sticks with suction...)

    I am wanting to get a second fan fitted directly under the shower (proper IP rated etc) and bolt than onto the existing fan so they work together, am I also able to plug into the existing duct so in theory have two fans for one bathroom.

    An electrician is coming round next week to fit some outside lights but I want to have some info on it first.

    Thanks everyone.
  2. Allsorts

    Allsorts Well-Known Member

    Yes, provided both fans are fairly equally powered and will operate at the same time.

    You obviously don't want one fan significantly more powerful than t'other as it could - theoretically - send its contents out the other fan.

    This has to be the easiest of jobs; the wiring is there and needs no modification - just an extension, the ducting is there and needs only a 'Y' branch, really it's as easy as it gets.

    I don't understand your comment about over-timing being against regs, tho'; having a timer that keeps it running for a few minutes after you exit makes complete sense. It may need a slight mod to the wiring, tho' - the fans will need a permanent live as well as a switched one.
  3. Bazza

    Bazza Well-Known Member

    Me neither. its usually the other way round. Building regs require a timer, and may solve your condensation issue.
  4. blarblarblarblar

    blarblarblarblar Active Member

    Why can’t you just fit a bigger in line fan, fitting a fan directly above the shower won’t make much if any difference, as steam is soon out of the cubicle area, 6 ft away isn’t a problem
  5. DIYDave.

    DIYDave. Well-Known Member

    Crazy fitting a ‘standard’ fan, ie. non timer model on a new build - penny pinching I recon

    Fan could also be a cheapo budget contract model with poor extraction rate - not all fans are equal

    Where’s it fitted - out through wall or in ceiling and vented through loft ?

    Upgrade to a decent fan, in-line will give better extraction rates generally and 100% go for timer model

    Idea is when switched off, can adjust over run from 0-20-30 minutes to clear steam (10 mins or there abouts should do it)

    When do you ever see a bathroom (small) fitted with 2 fans ?

    Not needed. Either c rap fan, c rap installation, no overrun - simples
    Allsorts likes this.
  6. JP.

    JP. Screwfix Select

    Sounds like a good quality centrifugal fan with timer/humidity stat is indicated..perhaps the one in situ at present is a 4in axial type fan?
    Last edited: Nov 10, 2018
  7. Mike83

    Mike83 Well-Known Member

    Surely the builders have to rectify this.
    I’m not sure the extractor is even wired correctly.
    Should the extractor not run continuously on trickle and when switched be boosted.

    If the current extractor isn’t doing its job make the builder fix it.
  8. blarblarblarblar

    blarblarblarblar Active Member

    Nope, the fan is a fan, you want a better fan you’ll have to pay
  9. Mike83

    Mike83 Well-Known Member

    But the fan should be designed to meet minimum extraction rates. Doesn’t sound like that in this case. Or the fan is in the incorrect position
  10. blarblarblarblar

    blarblarblarblar Active Member

    Think it’s part F, look it up and you may get some help from the house builder, but some how I very much doubt it.
  11. Mike83

    Mike83 Well-Known Member

    Strict guidelines in part F regarding ventilation.
    The builder designed the room, the extraction and ventilation, location of shower/window/ventilation/extractor.
    A modern extractor when designed and installed correctly should be up to the job.

    Why spend your own money fixing someone else’s problem.
    The maximum you should get is a little steam on a window or mirror.

    Having the fan come on with the light is surely wrong.
    Why should the light need switched on during daytime to have a shower????
  12. JP.

    JP. Screwfix Select

    I use a Manrose 6in through the wall type fan with integral pir..aye when you walk into the shower room it actuates automatically. I put an isolator switch outside the room so at night, before you go to bed, you can turn it off - saves hearing t fan when you are only going for a quick whizz. There sre no condensation probs whatsoever.
  13. aiwnjoo

    aiwnjoo New Member

    Thanks everyone, the fan fitted is a VentAxia Low Carbon model, apparently there are two modes on the fan which requires a jumper change. I wonder if the builder would have just left it on stock and increasing it may help?

    The fans I was looking at provided 97m3/hr extraction, however the ventaxia seems to be around the same price but not sure on the model so cant confirm its speed?

    I think I will try replacing the current fan if you still recommend that? Before looking into getting a second concurrent fan.
  14. Allsorts

    Allsorts Well-Known Member

    I think common sense would suggest what you say - first check the existing fan is working as it should. If it is as good(poor) as it gets, then check to see if there's a significantly more powerful alternative than can simply replace it.

    Finally consider a second vent/fan.

    Do you have decent access to the roof above this bathroom? Possibly an alternative solution - should you decide you do need to go the replacement route - would be to fit a second vent grill, but have them both being extracted by a single in-line fan, say a 5" model. You can get Y-branches for such things.
  15. Pollowick

    Pollowick Well-Known Member

    Have a look at fans with Humistats built in. They have an overrun timer and switched with lights to remove odours and also detect when the humidity level is above normal, that is when you are showering, and kick in at that point to pull all the moist air out. I have one fitted, with an additional pull cord if I require a further couple of minutes.
    Allsorts likes this.
  16. RaspberryMark

    RaspberryMark New Member

    The fan should have come with an airflow test (PEATA) certificate, showing that it does meet the minimum airflow requirements - Part F requires this for new builds. The "toilet paper" test is not sufficient. Many "contract" fans don't meet regs when installed - see
    Two intermittent fans on the same ducting is a bad idea, for the reason Allsorts mentions. Inline with two inlets would be a better option.
  17. blarblarblarblar

    blarblarblarblar Active Member

    Wot say wot wot PEATA
  18. Handy_Andy

    Handy_Andy New Member

    Out idiot 'newbuilders' Bovis not only scrimped on the quality of the fans but employed people who didn't even bother to install them properly. After several years of pitiful performance one of them packed up and in the process of replacing it I noticed that the anti-draught flaps had been left on which is against what the instructions said when installed in a ceiling (and were probably held shut by the ducting anyway). So I wouldn't be surprised by anything, I dread to think how many hundreds they did like this on our estate. And don't even get me started on the plumbing... Would never buy a 'mass produced' new build again. As said above I'd get them back to sort it, if you've not been there long.

Share This Page