I'm in the UK. I believe this house was built in the late 90's. The bathroom (and toilet) both have ceiling fan vents with a plastic guard covering the vent.

When I removed the guard to replace the fan, (I thought it was broken as there was no noise coming from it) I realised that there was no fan! There's also no wiring. It looks like a rubbery vent going straight up.

What's the purpose of this? It doesn't seem to be doing anything as there is mould building up in the bathroom.

Any help would be much appreciated.

I've attached a picture with the guard off for reference:

Also, apologies if this has been posted before. This setup may have a name but I don't know what it is so I'm not having much luck with Google!

  • How dirty is the guard? Like, return-grill dirty, or supply-register clean? That should give an indication of if it's an exhaust or a supply, but do you even have HVAC? If so, what are these doing when it's on?
    – Mazura
    Jun 2 '16 at 23:00
  • @Mazura it looks quite clean actually! It's only got a few bits of dust on it. It doesn't look like anything like what I've seen on other guards.
    – bean
    Jun 3 '16 at 12:40

It is possible there is an "inline duct fan" half way along the duct.

enter image description here

These are "designed to produce higher working pressures for applications that require high air flows, with low relative noise." compared to cheaper surface-mounted fans.

Your duct presumably runs through your attic/loft and is accessible from there.

There will probably be an isolation switch for the fan somewhere just outside the bathroom. This may incorporate a fuse. If so, you could check the fuse is Ok and that the switch is working.

Typically, power to the fan is provided via a pull-cord operated light-switch and often there is a separate permanent-live feed so the fan can continue to extract damp air for several minutes after the room has been vacated.

  • I will have to have a look for this once I get into the loft. Unfortunately it's out of reach for me at the moment as I don't have a ladder! I've checked outside and inside both bathrooms and I can't find any switches/draw strings that serve no purpose so I'm guessing they're connected to the light? Thanks for your response.
    – bean
    Jun 9 '16 at 6:40

It may be a passive ventilation system (which are more commonly found in apartments). You should follow the duct and see where it goes. I only say that because, well, it may just be a shoddy job, or it may be going to an HVAC sytem or something crazy. This is an unusual thing.

You should have a vent and the vent should go outside. For best results the vent should have a fan.

  • I see. Thanks! I've not heard of them. I'll look into passive ventilation. From searching I don't think it'll be as large an HVAC system as I'm in quite a small building. Although I've just tried to follow the duct and I'm going to need to get myself a ladder before I can find out anymore!
    – bean
    Jun 2 '16 at 22:00

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