bathroom ventilation

[kreyszig]

Hopefully it won't be decades before we embark on a proper refurb of our bathroom, but in the meantime I'd like to add a ventilation fan.

Our eaves extend down/out a fair way, and there's no soffits as I understand them (i.e. you can see the rafters from outside) so I am a bit concerned about venting out of the side of the wall and having moisture getting trapped underneath the eaves (the paint is in poor condition as it is), and since I have scaffolding up at the moment I've been thinking about going through the roof instead.
I've seen some nice lead ventilation apron things that would certainly be a lot nicer to look at than a vent in the side of the wall. Not that they would be visible from the ground, come to think of it!
I guess the risk is that any leaks in the ducting are then allowing moisture into the loft space. Which is a cold loft btw - no membranes or anything. So I have ease of inspection on my side!
Any good reason to favour going through the wall rather than the roof? Can anyone recommend a good fan for this purpose, and can I legally wire it in myself?

 

[Zebra]

One reason to go through the wall and avoid ducting through a cold roof space is that the moisture will condense inside the ducting when it passes through the cold loft space and you will end up with a tube full of moisture laying on the loft floor, or dripping back down into the room. I've seen this a couple of times. It may be possible to insulate the ducting well enough inside the loft to prevent this, but I don't know how effective this would be.
As for choice of fan - well, there are options. A standard 4 inch fan is enough for the average bathroom. It has to be 12v if situated over the bath or shower tray, it can be 230v elsewhere. There are timer models which come on with the light and stay on for a set time afterwards. There are humidistat models which detect humidity. There are pullcord models which you have to activate manually. There should be a fan isolator switch outside the room, to be able to disconnect the fan for maintenance, and when not required.
Under Part P you are not supposed to do wiring in a bathrooms yourself, no. However...........

 

[Flyfisher]

I'm also looking at a bathroom refurb at the moment and I plan to take the extractor pipe through the roof. As kreyszig says, some properly done leadwork would look quite good, though in my case it's more of a necessity due to the bathroom location.

One of the things that's exercising me at present is how to minimise steam spillage from the shower into the bathroom without having a really powerful extractor fan that will create a partial vacuum and make my ears bleed :lol:

So I'm thinking about how small I can leave the gap between cubicle and ceiling, which has led me to wonder if there's any reason for a shower cubicle to be open to the bathroom at all? Could it not be some sort of fully enclosed cubicle? Not totally airtight, of course, and still with an extractor fan, but something to prevent steam from spilling into the bathroom, with all the inevitable condensation. It's probably not a practical idea, but I'm not entirely sure why.

As for wiring within bathrooms, I appreciate the regs position on this but if the extractor fan is located within the attic (or otherwise outside the bathroom) then would that count as not being within the bathroom?

 

[mattice]

I went for an inline fan in the loft, all wiring can be outside of the bathroom. The fan is silent http://www.tlc-direct.co.uk/Products/SLTD350SILENT.html and I have all of the ducting insulated and piped out of a wall vent, this could equally be a roof vent. Instead of a switched fan I put a humidistat in which I'm pleased with (it only sucks nice warm out when it needs to) and it meant I could keep all of the electrics outside of zone 1 and 2.

It's worth doing the sums, I over sized mine a little and the bathroom door slammed shut when I switched it on and whilst the fan was silent, it sounds like a huricane blowing through the cracks :lol:

 

[a twig]

I went for an inline fan in the loft, all wiring can be outside of the bathroom. The fan is silent http://www.tlc-direct.co.uk/Products/SLTD350SILENT.html and I have all of the ducting insulated and piped out of a wall vent, this could equally be a roof vent. Instead of a switched fan I put a humidistat in which I'm pleased with (it only sucks nice warm out when it needs to) and it meant I could keep all of the electrics outside of zone 1 and 2.

It's worth doing the sums, I over sized mine a little and the bathroom door slammed shut when I switched it on and whilst the fan was silent, it sounds like a huricane blowing through the cracks :lol:

Definitely the best way IMO and precisely what we had, before the sparky doing his re-wire decided that "like for like" meant "something completely different". So now that I have the all important Part P certificate, I shall be returning to a configuration as above.

 

[Roger H]

Have you considered heat recovery ventilation? e.g. http://www.vent-axia.com/range/lo-carbon-tempra.html
I think quite useful for reducing humidity in traditionally constructed buildings.

 

[kreyszig]

Thanks all, some good stuff there. I like the in line fan above, but hadn't considered heat recovery - I'll have a look into that now I think!

 

[MatthewC]

One reason to go through the wall and avoid ducting through a cold roof space is that the moisture will condense inside the ducting when it passes through the cold loft space and you will end up with a tube full of moisture laying on the loft floor, or dripping back down into the room. I've seen this a couple of times.

My bathroom extractor goes through the cold loft (and then the roof above) and doesn't seem to do suffer from condensation at all, possibly because the ducting is plastic, not metal?

NB With the thickness of the stone walls, going through the ceiling and the roof was a no-brainer!

 

[Spoilt Victorian Child]

I'm currently planning on installing a fan and the best solution till I read this was indeed to go up through the roof space. This has given me food for thought, thanks.

 

[Keithj]

Our bathroom one is set in the ceiling, vents horizontally through placcy "elephant trunk" across the attic, and out just below/behind the gutters with a nifty one-way louvred flap thingy. We've not had any problems apart from the original fan being seriously noisy. I found and fitted a very quiet one - so quiet you wouldn't know it's running, but it does the job well.

 

[Spoilt Victorian Child]

Hi Keith - what model of quiet fan did you use?

Am on the edge of getting a new fan fitted, so it's decision time for me.
Looking for effeciency and low noise. Bathroom is small, about 2.5m x 2m.

 

[Keithj]

I can't remember at this distance where I got it from, but the writing on it says "SwiftAir".

I recall searching the internet and looking at the specs of the various fans, noise levels, etc. I think the more powerful the fan is, the noisier. I opted for quieter and set the "run-on" that the light switch triggers to its maximum duration.

 

[Spoilt Victorian Child]

Thanks, will look them up.

 

[a twig]

Last weekend I finally fitted ours that has been sat in the loft for 6 months.

Whipped out a roof tile and put in a Klober Universal Tile vent, was a bit of a faff as like all Universal things it required a bit of modification to fit, but after 30 minutes and only a couple of minor cuts it was all sorted!

Then in the loft, an inline Manrose CF200T, all properly isolated and fused, and running off the light switch. You can buy it as a kit which helps and makes it pretty cheap. Plastic ducting from grille in bathroom ceiling to inlet, and from outlet to roof tile vent.

It's quiet, and we have found it good compromise, shifts some air but doesn't slam the door shut for you! Took a similar approach of setting the run on to 20 mins to compensate for lack of oomph, very happy so far.

 

[LadyArowana]

If you have baths with lots of bubbles instead of nasty showers then you don't have soggy air. We had to have the silly fan arrangement linked to the light, I use a lovely scented candle or two instead if it's dark.

 

[jocelyn plummer]

We just leave the window open!!!!!

 

[mims&pip]

We just leave the window open!!!!!

Same here, Jocelyn :roll:

At our last house - which for those that don't know, the term *a bit of a project* was a severe understatement - Pip refused point blank to bow down to building regs requirements and fit the obligatory extractor fans in the three bathrooms and utility :shock: As we had planned to stay long term when works commenced we weren't really concerned with selling the house and requirements of future buyers, but our plans changed and the works were completed much more speedily than we had originally intended.

When our - independent - building inspector came to sign things off in October 2014, he too turned a blind eye to their absence, something I was very surprised about tbh. We always fling wide the windows and have never fitted an extractor yet....naughty, I know, but we seriously hate the things. There's an extremely offensive specimen slap bang in the middle of the current kitchen (but possibly soon-to-be utility room) here and I can tell you now, its days are numbered :lol: :lol: :lol:

Mims x