Opinions needed - bathroom extractor fan positioning....

Hi all. Just to quickly introduce myself, I'm not a skilled DIY-er, but, with guidance, can normally competently undertake relatively simple jobs around the home without calling in the cavalry (eg replacing the broken cooker hob with a new one, etc).

I have a question regarding the extractor fan in my bathroom. We are in a ground-floor flat, and the bathroom has an extractor fan situated on the external wall that activates when you turn the lightswitch on. There is a window in the bathroom. I've attached a number of photos to illustrate what I'm referring to.

When we have showers, the bathroom steams up immensely, causing mould spots to appear on the wall every few weeks (requiring a clean with bleach). The fan is always on when we have showers, and the top (smaller) window is open. When a shower is finished, and the bathroom is vacated, the main window is opened to allow the steam to escape faster.

The previous occupants had fitted a rather tall wall unit right infront of the extractor fan, which, to my untrained eye, seems rather silly, and, I assume, prevents proper extraction of the air from the room. The build-up of steam from a shower seems to confirm this for me. But, I have recently seen extractor fans that have a 'plate' mounted in front of the opening to the fan, which is basically much like the scenario with the wall unit being mounted a few centimetres in front of the extractor fan (eg http://www.extractorfanworld.co.uk/airflow-quiet-air-qt100b-129-p.asp ). This would suggest to me that a fan can perform fine even with something mounted closely in front of it. Is this true, and thus is the cabinet's position perfectly fine?


What are your thoughts? Is the unit too close to the extractor, and thus hindering it (hence the build-up of steam)? If not, why is there a build-up of steam? What more can we do to prevent this?

If the cabinet is too close, I'm happy to remove it and install a smaller one that will keep the extractor fan opening free. But this has brought up another issue; there is a wired shaver socket in the cabinet. What can I do about this? Is there an easy way to make it safe, and just tuck it in behind a new cabinet? I've unscrewed it in the pics below so you can see the type of wiring:


Finally, I have considered getting a more powerful extractor fan. Are there any that you would recommend? Additionally, I would like one that stays on either with a timer, or with a humidity sensor. Would this work with the set-up we have (ie the fan turns on when the bathroom lights are turned on, and turns off when the lights are turned off); would the fan stay on afterwards? I'm thinking it would just be de-activated as soon as we leave the bathroom and switch the lights off (not what we want).

I'd really appreciate your collective input - this is starting to drive me a bit nuts! Thanks.

First consideration is air flow. The unit does appear to be obstructing the flow. If you are opening the window and the fan is operating then the air will flow window to fan. It won't flush the room and will cool the room causing more condensation. Is there sufficient gap/grill in the door to allow the fan to work properly? Test roughly by shutting door with fan running wait a few minutes then open door if fan note changes then it needs more air into room.
As for the fan itself; you could increase the size/capacity but, as above, it may not help. Useful in these circumstances is often an input fan although this may be difficult in a flat.
The reason for getting condensation/mould is that the wall ceiling surfaces are colder than the air. Do you have adequate heating in the room all the time (not just when using it)? With a good level of permanent heating the structure will be warmer and the condensation less.
Suggestion is to move unit first then work by stages rather than leap in with expensive unworkable 'solutions'.

Extraction is only half of the story. Even if you have sufficient extraction, condensation forms when moist air meets a cold surface and the water it contains condenses on it. Whilst ventilation is vitally important to get rid of the moist air as quickly as possible giving it as little chance as possible to condense. Keeping the fabric of the building warm is the best way to prevent condensation forming in the first place. Insulation helps. Are the walls and ceiling well insulated?

Is there sufficient heat in the bathroom? or, is the room only heated for brief periods so that the 'fabric' of the building doesn't have time to get warm? Does the heat go off before the bathroom is dry, or whilst it still contains wet towels?

Also warm air carries much more moisture than cool air, so more moisture will be contained in the air that is extracted if the air is warmer. (I know sucking expensive warm air outside goes against the grain a bit. If it's a major issue, some extractors have built in heat exchanger to recover some of it)

I had a similar problem when I moved into my current house 15 years ago. Despite having a good extractor, water would run down the bathroom walls, drip off a concrete beam above the window and run down the blinds which went black with mould in just a few weeks. I exchanged the towel radiator for a traditional radiator, the room got much warmer more quickly. No condensation forms now, not even on the mirror. (The only place is on the WC cistern when the incoming water is very cold, like now!)

A fan with a humidistat is also a good idea, as it will keep the fan running until the moisture in the air is at a normal level, handy if you leave towels drying in the room after you have left and would normally have turned the fan off.

Many thanks. Well this is certainly an eye opener. From what I gather, the way we've been tackling the problem is basically exactly the opposite of what we should have been doing! Yes, there is very little air coming in under the door, so I assume the solution to that is to either cut 1cm off the base of the door (not so easy when you've not got heavy-duty power tools), or leave the bathroom door open a crack when showering (the latter being the much easier solution). After trying this, I can confirm the build up of visible steam was notably less, though there was still a lot of condensation on surfaces. Additionally, we do have a towel radiator in the bathroom, but it is generally a cooler room than the rest of the flat (and obviously us having the window open when we showered (thinking it would help clear the moist air) let the cold winter air in, making the room even cooler. By leaving the door slightly open, my only concern is that the moist air would exit the bathroom and cause the hallway to be damp too. But, I assume, if the extractor fan is on, and is pulling air into the room from the rest of the flat, this shouldn't really happen?

Clearly the next main thing I need to do is install a more efficient extractor fan that has either a timer or a humidity sensor (so that it remains on after we leave the bathroom to clear the remaining moist air). This leads me onto two technical/electrical questions:

1) To gain access to the fan, I will need to remove the wall cabinet (and I might as well replace it with a smaller unit whilst I'm at it). But there is a wired shaving socket inside the unit - see pictures. What can I do about this? Is there some way of safely terminating the wire and tucking it back into the hole in the wall it is coming out of, so that I can mount a new cabinet over it? If so, are there instructions on how to do this somewhere on the net?

2) Once I've gained access to the extractor, and found a suitable upgrade to replace it with, will I be able to fit one that has a timer/humidity detector, seeing as my current extractor comes on/off with the main bathroom light-switch? Will there be power sent to it even after I leave the bathroom and turn off the light, for the fan to continue to extract the moist air? If so, again, are there online instructions on how to do this, and is it a relatively easy task?

Again, thank you for your words of advice so far - it has proven very useful. Hopefully, with further help, I can eliminate this problem completely and have nice, condensation-free bathroom.

Has anyone got any suggestions/advice for the following?:

1) To gain access to the fan, I will need to remove the wall cabinet (and I might as well replace it with a smaller unit whilst I'm at it). But there is a wired shaving socket inside the unit - see pictures above. What can I do about this? Is there some way of safely terminating the wire and tucking it back into the hole in the wall it is coming out of, so that I can mount a new cabinet over it? If so, are there instructions on how to do this somewhere on the net?

2) Once I've gained access to the extractor, and found a suitable upgrade to replace it with, will I be able to fit one that has a timer/humidity detector, seeing as my current extractor comes on/off with the main bathroom light-switch? Will there be power sent to it even after I leave the bathroom and turn off the light, for the fan to continue to extract the moist air? If so, again, are there online instructions on how to do this, and is it a relatively easy task?

1) The correct way to decommission wiring would be to disconnect it from source and remove it. This depends upon how it was wired in the first place. But the shaver supply may well be from the lighting circuit, if so, and if it has a permanent live connection, it could make an ideal supply for your new fan.

2) If the existing fan does not have a "run on" facility that keeps it going for a few minutes after the light is turned off, that does suggest that you may need to add a permanent live supply. (Check first that it is not there already but not used.) Providing a permanent live could be achieved as in item 1) above, or possibly, if the existing cable goes to a "loop in" ceiling fitting. Then simply swapping the live connection from the switched live to the permanent live terminal may be all that is required for a fan with an integral humidistat or switch. But again this all depends upon how it was wired in the first place.

The fan will require a suitably located facility that isolates all live and neutral connections for cleaning and maintenance.



Also as it's in a bathroom will require you to notify your LABC before starting work and pay their fee. In this case the fee may be more than getting an electrician in who can self certify. For basic Part P info, Click Here

You're right - leaving the door open will result in mould growth on the ceiling outside the bathroom.
You could terminate the shaver socket wiring by taking the cable through the back of the new cabinet and either fitting a blanked box or just refitting the socket.
As Stem said, you need a permanent live to the fan to use one with a humidistat. If the fan is as suggested with a link to the lighting circuit via a loop-in in the ceiling you could fit a stand alone humidistat which would save buying a new fan.
A bit of detective work is needed, but please ensure all circuits are off in case there is an unexpected permanent live lurking there.

Many thanks for the informed replies, and apologies for my delay in replying (Christmas and the new year got in the way!).

To summarise, I did the following:
• Removed the wall cabinet
• Terminated the wire that previously went to the cabinet shaver socket
• Removed the Wickes pullcord extractor fan
• Filled in the fan mounting holes and tidied up the wall
• Stripped away any loose paint and then re-painted the wall with a 'stain protective' primer, followed by the colour coat (having added a mould-proof additive to the colour paint)
• Added a new circular Vent Axia 'Eclipse' extractor fan, with timer
• Added a new mirrored wall cabinet

The new shorter wall cabinet was purchased to specifically prevent the fan opening from being blocked, as it was with the height of the previous unit (see previous photos).

I had to revert to using the new extractor fan as purely an on/off fan controlled with the light-switch (I had been misinformed that there would likely be an additional live wire leading to my previous fan, which there wasn't). Adding an extra loop of wire when I connected everything up fixed that. Not ideal, but it works.

The new fan seems to extract a lot more efficiently than the previous. We now leave the door slightly ajar when showering to allow a throughput of air, which seems to work better. We still get moisture on the walls, but I believe it is less than previously (presumably due to a) the fan opening no longer being partially obscured, b) a more powerful fan, and c) having a throughput of air) and there is noticeably little steam when showering now. Additionally, I've not felt that any moist air is leaving the bathroom whilst the door is slightly ajar, which I was concerned about.

Finally, as I've unfortunately been unable to make the run-on timer in the new fan work, we have resorted to opening the window when leaving the bathroom after a shower, to help clear the air. I don't want to leave the bathroom lights on (and thus the fan) just to do this, so this is my solution. It's a bit nippy afterwards though, with this weather!

Thanks for all the advice and tips - I've put them to use!

Looks nice.

Looks good, I haven't read the whole thread but if you cut a bit off the bottom of the door you won't need to keep it ajar during using the bathroom

londonboy said:

Looks good, I haven't read the whole thread but if you cut a bit off the bottom of the door you won't need to keep it ajar after using the bathroom

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Never thought about this before. But, on having a look, I've just realised our cat could probably get under the bathroom door when shut!

londonboy said:

Looks good, I haven't read the whole thread but if you cut a bit off the bottom of the door you won't need to keep it ajar during using the bathroom

Click to expand...

Thanks. I'm happy with it (especially as it's the first proper DIY mini-project that I've done). Though now I realise that once you start one thing, you notice the issues with others and then need to fix them (which invariably turn out to be MUCH bigger jobs than initially anticipated) such as tidying up the bathroom window frame (removing blind, sanding frame, filling, sanding, undercoat, painting etc).

Regarding cutting the bottom of the door off, this isn't really an option as I don't have the facilities to do it; I live in a flat, and neither have the space nor equipment to perform such a task. Leaving the door ajar is an easy alternative I am happy to go with.

..might be worth talking to your local carpet shop - they have tools that trim the bottom off a door while it is in-situ. (To allow for installation of deeper pile carpets).

I dont think he needs a bigger gap!

Scoby_Beasley said:

But, on having a look, I've just realised our cat could probably get under the bathroom door when shut!

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Frankiej60 is in London, Scoby_Beasley's in Durham. I doubt they share a bathroom.