Bathroom vents in loft

[James P]

Hi All

I am the first occupier of an ex showhome that was constructed in 2002, I've been here 4 months. I needed to go into the loft for the first time at the weekend and noticed some things.

There are two bathrooms on the top floor of this 3 storey house and the extractor fans are just venting straight into the loft space. One of the fans has about 1 meter of silver insulated piping connected to it but it doesn't go anywhere, and the other doesn't even have the piping - you can just see the fan from the loft.

The funny thing is that there are two vents in the roof tiles. One isn't being used and seems to be just providing a nice breeze into the loft and the other is connected to a big grey pipe which I guess would be the soil stack - although I didn't realise it at the time when I unhooked it to peek down and have a listen (thought it went down to a ground floor extractor fan). Am quite surprised that it didn't stink to high heaven when I did that!

Am I right in thinking that these fans really do need to be vented to the outside air? Common sense says "Yes" but I'd really like to be able to go back to the builder and say it's against the building regulations if needed.

Cheers, James

[R]

Using a Y branch and some more of the silver foils type tube just connect them to the existing outlet and roberts your aunties husband.

[James P]

Yep I will try and get the builder in to do this as they should have done it properly in the first place IMHO !

Cheers James

[Lurch]

On Tue, 6 Mar 2007 09:36:11 -0000, "R" mused:

Y, or T, both will do the job. ;)

Also you'll be wanting 2 backdraught shutters otherwise the one fan will be pumping into the other room when they're not both on at the same time.

[David Hansen]

On Tue, 06 Mar 2007 09:15:51 +0000 someone who may be James P wrote this:-

How are both these vents terminated?

When sorting this out check that the loft is properly ventilated after this vent is set to do something more useful.

Guessing is not much good.

Look for terminals for this in the walls. If there aren't then how do you know what the grey pipe is for?

In modern drainage systems drain air is generally fine. Banishing interceptor traps and ensuring a good flow of air through the drains was a good step forward.

Yes.

Quicker and easier to fix it yourself. Assuming the fans don't have back-draught shutters to connect both top floor fans to the one vent use a Y-piece with a built in flap that will isolate the other fan from the airflow if it is not on or allow both to discharge if both are on. I assume both are of similar ratings.

[James P]

I don't know enough about what I am looking at but the pipes lead up to a widening plastic part that looks like the end of a vacuum cleaner about midway up the roof. Tile vents?

Will have another look later on, but my uncertainty is the main reason for wanting to get the builder back in, this in theory should be easy as they are still on site.

My detective work involved turning on the ground floor fan and I got no breeze up the pipe. I also know the general location of the soil stack from previous corrective work by the builders (hot and cold pipes were randomly switched throughout the house... )

Good advice, cheers. Yes the fans are quite similar.

I have often (well, not really *grin*) wondered why the moisture in the air going up these pipes doesn't immediately condensate in the pipe and run back down to the fan. I guess this does happen to a degree but is there anything I should be watching out for?

Cheers james

[Graham]

Hi James,

About 18 months ago we renovated our bathroom and immediately encountered drafts streaming in to the bathroom through the extractor fan, replacing the flap with another design made no real difference. The problem seemed to be that when the wind blew against the outside wall on which the fan was mounted the pressure difference was just too much for the flaps.

After some hesitation we decided to see what would happen if we cut the ducting and allowed the fan to exhaust straight into the loft. I've regularly checked the woodwork around the opening and elsewhere and there's absolutely no sign of moisture build up. The loft is fully ventilated by way of slots all along the soffit boards.

And the drafts? Well they disappeared immediately.

I don't know what the regs say but this has worked for us.

Graham

[David Hansen]

On Tue, 06 Mar 2007 13:36:12 +0000 someone who may be James P wrote this:-

To the best of my knowledge the soil pipe should go straight up and terminate in a birds nest, something like

didn't say which country you are in but, assuming there has not been some devilish change in the regulations where you are it may well be that the stack does not comply with regulations.

Put a source of smoke in the ground floor room and see where it comes out.

The proper way of arranging vertical ducting which contains moist air is to have a trap at the bottom which leads to a drain. This will catch moisture running down the sides. There are a few ways of doing this, the easiest being a special piece that fan makers make/made which just fits into standard ducting.

Many don't bother.

[John Rumm]

Some BCOs may allow a air admittance valve instead.

It would seem unusual to vent a ground floor fan to the top of a three storey house. Might be worth looking for any vents at about ground floor ceiling level.

[Peter Johnson]

In my house, 17 years old, the bathroom/en suite extractors vented into 4in of insulation.

[David Hansen]

On Tue, 06 Mar 2007 15:03:04 +0000 someone who may be John Rumm wrote this:-

Should there not be at least one open terminal in any branch off the sewer, so that one can use an air admittance valve on new extensions to the plumbing?

Indeed.

[David Hansen]

On Tue, 06 Mar 2007 14:35:44 +0000 someone who may be David Hansen wrote this:-

These are still made.

[James P]

You didn't say which country you are in but, assuming there has not

I am in England (Wiltshire). I did actually have a problem with a foul odour in one of the bathrooms coming from the shower drain trap when I first moved in. This was fixed (bodged) by cutting out a section of pipe and replacing it with a non return valve.

Yep - got it. It does come out of a vent, just not the one I was expecting. Seems to take a strange route across the house when just going out the wall would have done.

Three guesses for what they've done here. You'll only need one *grin*

Cheers

James

[Andrew Gabriel]

Or use fans with front louvres which close when off.

Another problem you might get is condensation running back down the pipe and coming through the fan.

[Andy Hall]

That can be fixed by using ducting with insulation.

[David Hansen]

On Tue, 06 Mar 2007 17:56:49 +0000 someone who may be James P wrote this:-

I suspect that they ran out of time/effort/ability to go through the roof and fit a proper terminal and instead connected the stack to what was supposed to be one of the fan outlets and didn't then connect the other one up as this would have made it obvious.

The wiring does not comply with regulations either as joints should be inside a suitable enclosure. Tape wrapped round terminal blocks is not a suitable enclosure.

Did you have a survey done?

[Lurch]

On Wed, 07 Mar 2007 12:28:13 +0000, David Hansen mused:

Common practice that, a vents a vent AFAIAA.

On some of the sites we used to do the house builder was supposed to duct all fans etc... but never bothered. I suspect this is the case here.

The severe melting of the cable would be more of a concern to me.

Now I'm not condoning this, but a lot of lights and fittings in a showhome would be fitted temporarily but i reality were left there. Again, laziness on the house builders part.

[Lurch]

how many spare video amps you got?On Tue, 06 Mar 2007 13:55:02 +0000, Graham mused:

The regs say no.

[John Rumm]

You need one with backdraft flaps on the external vent then. The harder the wind blows on these the harder it holds them shut.

You won't necessarily see the moisture... but the dry rot will show you where it is eventually!

I got asked by a friend to diagnose why the extractor fan in his bathroom has stopped working. Initial checks showed that power was reaching it, but the blades though free to turn were not spinning up - looks like the motor was shagged. So I ordered a new fan from TLC and went to fit it for him. Only when I took the old one off did I see something a bit odd - the was a plastic feeling lump of cloth stuffed into the exhaust duct. Pulled it out and found it was a white nylon body warmer style jacket! It seems that when he let the place for a few months, the tenant had decided that there was obviously a draft and set about fixing it! Quite how that particular fix came to mind though I am not sure (disconnecting the wire and selotaping a bit of card over it I could understand, but dismounting the fan, blocking the vent, and the re fixing it, and allowing it to run against a blocked exhaust until the motor burnt out seems a little disingenuous).

[Roger R]

Some years ago when I moved into a brand new house the bathroom sink was a bit 'slow'. On removing the bottle type trap it contained a neatly rolled up empty cigarette packet, presumably placed there for 'aggravation value'. Possibly the blockage in your vent was made with the same intension.

Roger R