Bathroom Ventilation Requirements

[alan]

In order to comply with he Building (Scotland) Regs 2003, as far as I can see, I need to install a mechanical ventilator with a capacity of

15 l/s in my proposed bathroom. The bathroom will also have a fairly large opening window.

It has been suggested to me that I need the fan linked to the light switch with a delay timer to keep it running after the lights have been switched off. Is this really required?

I can see the need if there was no other means of ventilation, but it seems pointless as I won't use the lights until it is dark and what is the point in only having the mech. vent active when its dark!?

TIA Alan

[Mike]

Not in England. A separate switch or pullcord is acceptable. Whether Scotland is different I don't know.

BTW, would you actually use it anyway ? I'm sure a lot of these fans fitted under the new regs never move.

[William McNicol]

When I had huge amounts of work done in my house here in sunny Scotland, the main bathroom which has also has a large opening window has the fan activated by a seperate switch. The shower rooms, which are all windowsless all have the extractor fan tied in to the lights with an off delay. Seems very sensible to me. This was all architect specified in a Grade 2 listed building, so I assume it was OK under Scottish regs, although I can't be rsd to look...

I use the bathroom one after a shower or bath in cold weather when I wouldn't want to open the window.

Cheers,

William.

[fred]

In article , [e-mail] writes

What's the problem, the requirement for the mechanical ventilator or the one to tie it to the light?

If it's the need for the fan then I'd rather have that than an open window in winter.

If it's the light linking then there's nothing stopping you connecting it to something else after your building inspection, mine's connected to the shower master switch. The rule's there for those who don't know better.

[alan]

connecting it to

better.

Providing a fan on a separate switch is not a problem as it's what I was planning to do. Linking it to the light with a delay timer to keep it running after the lights are off is my concern. As you say it is always possible to do one thing to get it signed off and revert to another thereafter.

Alan

[fred]

In article , [e-mail] writes

I agree it's a pain to have a fan come on when you have a late night visit to the toilet or just want to wash your hands but I do like having a delay on mine, it's set to an hour but then is never switched on unless the shower is used or if I toggle it to clear the air a bit.

I think you need a 3pole fan isolator outside the bathroom to meet electrical regs too. If you were to put a narrow pattern switch beside that you could use it to break the link between light and fan trigger so that the installation could meet regs or suit your own needs at the flick of a switch. A separate switch could provide the manual actuation or use a fan with an extra manual actuation pull cord.

I suspect you do know all this however & just fancied a rant about the regs ;-)

[chris French]

I installed one when I did our bathroom, I had mine operated by a humidistat which worked pretty well.

[Martin Angove]

[...]

Don't know how relevant this would be in Scotland but there has been quite a long thread here recently about humidity controlled fans. I have one on our bathroom, and I really can't see why (short of a MHVR system) you'd fit anything else. Only comes on when the humidity levels require it, so no pointless running in the middle of the night when you have a quick wee, and not foxed by taking a shower in the morning when the sun is bright enough not to need the light.

Obviously if there isn't a window then there is a different requirement.

It must be ok under England & Wales building regs as I had a conversation with our building inspector (just over a year ago) which went something like this:

Me: We have created a new bathroom and want to fit a window.

BI: Then it'll need mm2 of trickle vent, sir.

Me: But I hate draughts in the bathroom so I don't want a window with a vent. I'm going to fit a fan too, is that ok?

BI: No sir, the requirement is to reduce humidity levels and a fan linked to the light won't deal with that. You must fit the window vent.

Me: But I'm fitting a humidistat-controlled fan.

BI: Oh well, in that case, go ahead.

HTH

Hwyl!

M.

[nafuk]

I've just has a chat with builder here in the UK who said humidistat fans do not meet UK regs, you need the timer.

[Martin Angove]

The fan has a timer too. If you really feel the need you can set it to overrun *after* the humidistat has decided enough is enough. Ours is set to 10 minutes or so which gives a degree of hysterisis and ensures that it doesn't constantly switch on and off as the bath is emptying. It also has a Switched Live input so that you could trigger it from the light/sep switch if you wished to.

I don't know how on earth a timer-only fan could meet regulations given that our BI insisted the reason was to deal with humidity in the room, especially considering a bathroom with a window where the light may not be used every time you bath/shower. I suppose it's subtly different if you *do* have a permanent vent in the window.

Hwyl!

M.

[chris French]

In message , nafuk writes

But regs for what exactly? Yes it is needed for bathrooms with no window not necessarily for others.

Anyway builders and other 'pros' often misunderstand reg requirements.

[Mike]

I can't see any reference to this. Manual operation would appear to be fine (better be as I've got several of them and BCO has ticked them off) so anything better exceeds those regs.

[mattkelly]

I had a conversation about ventilation this morning with the building control officer who has approved the relevant bits of my extension which is currently being built.

He said that for bathrooms with an opening window his requirement was for extraction at 15litres per second controlled by a manual switch. Run on only required where there was no opening window.

This was in response to a letter I had written him asking if it would be OK to replace the timed run on fans indicated on the plans with humidistat controlled ones. I told him that I'd probably opt for switch combined with humidistat control and he said that would be fine.

[mungoh]

When I get round to installing the new en-suite bathroom I plan to fit one of those inline back-draught valves into the forced extraction pipework. There's "ventilation" and there's "draught".

Incidentally, I bought the cylindrical flap valve from BSS I think but I've never perchanced upon it since - anyone have a present source of such items?

Mungo