Soil stack open top

[Alistair Bell]

Hi,

We have recently moved house and in investigating the bad smell coming from the boxing in the upstairs bathroom I have noticed that the toilet discharges into the open top of the soil stack with a smaller diameter pipe, ie not sealed. A bath and basin connect as normal below this and on the ground floor a sink and washing machine before it disappears into the ground. A separate stack runs up the outside of the house to a vent, unfortunately I don't know what happens underground. The obvious answer to the smell would be to replumb the toilet "properly" into the top of the stack to seal it. However I am unsure if this would affect drainage etc, ie whether the outside vent is sufficient as the inside stack would no longer be "vented". Can I do this or is there a better solution for the smell

I suspect the "right" answer involves discussing with the surveyor why he didn't identify the significant work involved with redoing the soil stack but would be very grateful for other opinions.

Many thanks

Alistair

[Andy Hall]

Durgo would probably be your friend here.

[dom]

Yuck. The open discharge may have been a bodge solution to loo flushing resulting in blowing/sucking out the traps on the bath and washbasin. Read the Building Regulations

to check how it should be designed, you may be able to solve it with an air admittance valve. However I don't think it's acceptable for the valve to be boxed in.

[Lobster]

It's OK to box it in provided it's not 'sealed', ie if you provide ventilation into the boxing (eg a plastic grille). The point is not to end up with a potential vacuum within the boxing which would stop the valve from working.

Note that it's not always possible to fit one of these - eg, if the sewer to your house is at the end of a run, or if the sewer isn't vented normally at a property within two of yours (or something like that, I can't remember the details - probably tells you somewhere in the URL above!).

Search the archives of this newsgroup for "Durgo" - should help.

David

[David Hansen]

On Wed, 13 Dec 2006 21:16:59 +0000 someone who may be Alistair Bell wrote this:-

The toilet has a smaller diameter pipe? If so what diameter? Do you mean that the toilet discharges into a tee, but the top of this tee is simply vented to the bathroom.

Well you can do it, obviously. The question is whether you should do it and the answer is no. If you did it then when the toilet was flushed air would have to come up the pipe from the sewers and the outside pipe, against the downward flow of water. That won't work very well.

[The Natural Philosopher]

You probably want to add a proper coupling to the stack, attach the bog to that and fit a Durgo valve to the lot. I found a 3" one that fits inside my walls..just..

[The Natural Philosopher]

SSSHH!

It merely has to be 'accessible'

It's my business if that means pulling the cistern off the wall and opening that up with a jigsaw :-)

[The Natural Philosopher]

The issue4 here is to realise that a Durgo and a soild stack vent do not do the same job. Although a vent will prevent a stack vacuum, just like a durgo, the stack also vents positive pressure - i.e. methane caused by decomposing faeces etc..which a Durgo will not. The regulations are more about people replacing vents with durgos, than adding an extra one.

[Alistair Bell]

The toilet pipe is made up of two 90 bends that push fit together, the narrower end around 3 1/4" perhaps slightly more. This just hangs into the top of the 4" stack pipe in the corner of the room at floor level.

won't work very well as in not usable, or usable but definitely substandard? There certainly isn't room to extend the stack upwards to fit a valve at the proper height, possibly just enough to fit one straight on the top of a toilet entry tee. I realise that these solutions run the risk of flooding out the top of the stack if it blocks, but it could do that at the moment so I'm not loosing anything in that respect.

Thanks

Alistair

[The Natural Philosopher]

Fit a durgo immediately above the connector - -it won't flood. closes under positive pressure..it might weep slightly, but with a blocked pipe, that is the least of your worries..;-)

[Alistair Bell]

I think that is the best way forward, thanks for the comments, just got to get hold of the bits now but I have a day off work tomorrow so can go to the proper plumbers merchants not the chain DIY places that in West Cumbria seem to stock everything but what you went in for :-)

Cheers

Alistair