Plastic or Oak for a vent? Suggestions urgently needed

[oxalto]

Dear PPUKers,

This weekend I have to put in an external vent in a rendered gable end wall to allow the room which is becoming the bathroom to be properly ventilated by an extractor fan. I want the vent to come out of this end wall as it will be less visible here than anywhere else on the property.

We have removed the previous concrete/cement render and the gable cheeks are now being rendered in lovely lime mortar (scratch coat already done). I am aware that the conventional wisdom it that that this is the wrong time of year, but the incredibly mild winter has been kind to us so far...

I have seen a vent in solid oak which I much prefer to the look of the standard plastic alternative but the oak vent claims to be for internal use only. If it were a normal air vent I would have no concerns about using it externally, but I wonder if oak is a bad idea in this case since this fan will mostly be carrying steam from the shower. Is this an instance when aesthetic preferences should be cast aside? Will regular (daily) steam cause rapid deterioration of oak?

This vent will be exceptionally hard to get access to once the scaffolding is down so I need to make the right decision. The scratch coat is already on but the second coat is due next week so I need to do something in the next 48 hours! Please help with suggestions. I will even promise to post pictures once the scaffolding is down! Thanks!

 

[Feltwell]

How are you going to stop backdrafts when the fan is not in operation? Some fans rely on the external vent cover having flaps that close under gravity, I presume your oak one does not have these.

Does it have to come out of the wall? What's your roof covering? If slate or tile then there is a hidden vent system you can fit:-

http://www.lapvent.co.uk/mechanical_extraction.html

If you've thatch then this isn't much use!

If it has to be through the wall then I wouldn't personally fit the oak one - I'm not sure the steam will do it any good and in any event it will just be false. You may as well be honest and fit a plastic one, if it's up high it won't notice too badly I reckon, especially once the plastic has toned down a bit.

You say your wall is rendered but what is it underneath? Brick? If so you could fit an airbrick and use an adapter to convert from the (presumably) round exit from the fan to a rectangle shape, to then press up hard against the back of the airbrick - but you'd have to find some way of stopping backdrafts.

http://www.screwfix.com/p/manrose-round-pipe-to-channel-connector-100mm/12049

 

[oxalto]

"Some fans rely on the external vent cover having flaps that close under gravity, I presume your oak one does not have these"
Very true - only a few of the plastic ones I was looking at had these, but I did think they looked better than those without. The oak one doesn't have these.
I'm trying to avoid putting the pipes up through the roof because I'm worried about potential condensation. It will be better hidden if it comes out the wall as well, I think. I'm also told that these fans go wrong pretty quickly so I think I'd prefer it somewhere accessible for changing it in 3 years time! The wall is simply lath and plaster both sides at the moment, but the vent I was looking at was letter box shaped (via a converter). Either way there's still the question of backdrafts and its pretty windy up there. Perhaps I should stop being worried about how the plastic will look - it'll soon weather down I guess.

 

[Lime]

Perhaps you could compromise.
Use the plastic vent and have a decorative oak cover made for it.

 

[vicky whitworth]

Open a window instead?

We have a cast iron vent in our bathroom and no extractor fan. The vent is always open but it's high on the gable wall and I've never felt cold. We do have two big windows we can open though.

 

[Feltwell]

I wouldn't worry too much about condensation in your loft space - the moisture from the bathroom will all be contained within the ducting, and the ducting itself will be warmer than your loft so is unlikely to attract condensation onto it's outside.

If you've got easy access into your loft then a ceiling vent fitted to an inline fan (rather than a ceiling mounted fan) fitted to a lapvent would be an easy way to go, OK to get at for maintenance and would avoid holes in your wall. As for reliability, well I've never had a fan go wrong yet - but that's only me! I take it a vent in your eaves is not possible? That's the other option I've seen done before, but you have to be careful to keep the vented moisture away from woodwork.

I'm also told that inline fans are a lot quieter than wall mounted ones - see user reviews on links below which seem to agree with this. The wall mounted fan in my en-suite is very noisy - just from airflow, the motor bearings are fine.

http://www.screwfix.com/p/manrose-chrome-white-25w-in-line-centrifugal-shower-fan-kit/41379

If going out through the wall is still your preffered route I think I'd just go with plastic.

 

[oxalto]

Many thanks for all the useful suggestions. I am warming to the idea of the inline fan through the loft space. Can it be installed so that it extracts from the ceiling directly above the shower? It will still be better for it to go out through the "wall" which is only lath & render, as I don't want to start cutting through roofing felt and lifting tiles. The one that you've linked to looks good. Does anyone have any experience of these - any insallation tips or hints as to what to avoid?
Thanks!

 

[biffvernon]

Open a window instead?

+1

 

[Penners]

If going out through the wall is still your preffered route I think I'd just go with plastic.

I agree (with the advice, if not the spelling :wink: ). I think the constant dampening effect of the steam and drying effect of the wind/sun would soon cause warping in the necessarily slim louvres of an oak vent.

I would just add one word of warning about the gravity-closing louvres or flaps of certain types of plastic vents. It's true that they can reduce backdraughts through the fan, but they're not as effective as you might imagine. The wind can often blow the flaps open, allowing the draught in, and causing a hell of an annoying rattle.

 

[Penners]

Open a window instead?

+1

This might appear to be the more environmentally acceptable solution, but I question it.

If you open a window every time you have a shower or bath, the bathroom will get cold. Your heating system will therefore work harder to try and keep it warm. I suspect (although I have no empirical proof) that this will negate any energy savings you made by not having an electric fan.

 

[Feltwell]

Many thanks for all the useful suggestions. I am warming to the idea of the inline fan through the loft space. Can it be installed so that it extracts from the ceiling directly above the shower?

Yes - and you can get ones with a light built into them as well to illuminate your shower, if you wanted.

I don't want to start cutting through roofing felt and lifting tiles.

I think the whole idea of the lapvent is that you don't cut felt or lift tiles. I haven't fitted one myself, but I believe you do the whole thing from the inside - the vent pushing into an exisiting overlap (hence the name) in your felt, with no disturbance to the tiles. Have a closer look at that website - it could be a lot easier and certainly less obtrusive than a hole through the wall.

Open a window instead?

+1

You need a fan for BC these days I believe, if Oxalto has put in for that. Feltwell Towers has 2 showers - 1 in the bathroom without a fan, and one in the ensuite which does have a fan. In the ensuite I run the fan whilst showering, and when I get out there is no condensation on the mirror, leave the fan running for a further 5 minutes and the shower cubicle is fairly dry.

In the bathroom, with a window open it feels as if the room gets colder than the ensuite does and it certainly gets steamed up by the end of a shower. The mirrors stay clear if you have both windows open (the room is on a corner of the house - windows on opposite corners of the bathroom) but the cross-draft freezes you in cold weather!

Not very scientific and I appreciate the fan must drag in warm air from further within the house, but it is very effective in keeping the condensation down and is only ran for short periods.

 

[Feltwell]

I agree (with the advice, if not the spelling :wink: ).

Just testing old chap - I'd noticed a distinct lack of pedantry of late, I was starting to get worried that you weren't paying attention :wink:

 

[oxalto]

Great! - Thanks all.

The problem of opening windows as Feltwell points out is that in winter you get frozen whilst showering! I can't simply do so after my shower as I dash off to work straight away I don't want to leave a window open all day! Mrs Oxalto isn't a reliable window opener and so I currently regularly have problems shaving in a steamed up mirror. Then there's BC which we are trying to do our best to achieve when there's no good reason not to!

So fan it is! Would I be able to isolate the fan (and shower light) so that it didn't come on every time the bathroom light was turned on. That way it wouldn't really matter how noisy the fan is. Does anyone have a fan they would recommend?

 

[Feltwell]

Would I be able to isolate the fan (and shower light) so that it didn't come on every time the bathroom light was turned on.

Yes - if you've an electric shower than you can link it into the isolator for the shower. I had a low voltage wall mounted one in a previous house that was linked to the electric shower, it was set up so that it came on as soon as the shower isolator was switched on and turned itself off 5 minutes after the shower isolator was switched off.

If you've not got an electric shower you could just put a second pull cord switch in the bathroom just for the fan - and again get a timer version if you wanted, so you can leave it running for a short period after you've left.

I don't like linking them to the bathroom light either.

Lastly, if you went back to a wall mounted one then a simple option is one with a pull cord built in.

 

[Penners]

Would I be able to isolate the fan (and shower light) so that it didn't come on every time the bathroom light was turned on.

I believe the electrical regulations require you to have an isolator switch for the fan, located outside the bathroom zones. Assuming your fan is the run-on type, you will of course need a 3-pole isolator, in order to switch the neutral and both live supplies. Here's one type:

http://www.tlc-direct.co.uk/Technical/DataSheets/MK/3_Pole_Fan_Isolator.pdf

Make sure your choice of light complies with the zoning regulations in its IP rating:

http://www.allupandon.co.uk/bathroom-lighting-zones-diagram.html

 

[MdB]

and of course any work in the bathroom has to be signed off.

 

[Zebra]

Condensation in the loft space can be an issue in that the steam condenses inside the ducting as it passes through the cold loft space. In some cases it runs back down into the bathroom, and in one instance I've found a tube full of water lying on top of the loft insulation!

In terms of fans, Manrose are OK. Xpelair are good. There's the Airflow Icon ones if you want a fancy looking round one. There's one I'd recommend you not to use, but darnit I can't remember the name of it. What Penners says is true you have to have an isolator to comply with Wiring Regs.

No idea about the oak vent, sorry!

 

[biffvernon]

You need a fan for BC these days I believe

Oh but it's far more fun to live the life of an outlaw. And it's not like it's going to increase the risk of death, like driving as 31mph where you're not allowed to.

 

[biffvernon]

Open a window instead?

+1

This might appear to be the more environmentally acceptable solution, but I question it.

If you open a window every time you have a shower or bath, the bathroom will get cold. Your heating system will therefore work harder to try and keep it warm. I suspect (although I have no empirical proof) that this will negate any energy savings you made by not having an electric fan.

You are taking a very one-dimensional approach to the environment. Think holistically. I threw open my (un-vented) bathroom window at dawn this morning, breathed in the fresh air and was greeted by the joyous singing of a thrush in the sycamore not 20 feet away. Set me up for the day.

And you just want to listen to the whirr and hum and rattle of one of those newfangled devices? Huh!

 

[Keithj]

I don't know what it is with those extractor fans. There was one in the upstairs bathroom here when we moved in, and BC required us to put one in the downstairs loo/shower that we added. Both of them make the most infernal clattering noise when the wind's in the wrong direction.

Both come on with the light, and keep running for some time after the light's gone off. I'm told that's the way it has to be. There are convenient 2-pole isolator switches :twisted:

While an oak louvre cover would look nice, I don't know how well it would stand up to having humid air blown through it at regular intervals. Maybe you could make up an oak mask - something like a thin box with an opening underneath for the steam to escape through, and fix that over the placcy louvre device. No moving oak parts and thicker wood might last a few decades.