Soil sub stack issue

[arhplumbheat]

Hi all, Been to veiw a property today that the customer would like a new down stairs cloakroom with shower in. The room has been plastered and first fix of pipework is in and the drainage has been layed below a block and beam floor. The foul drain runs into an open chamber beneath a man hole cover.

The other end (at the moment) is capped off at floor level in the cloakroom. Provision has been made for the shower waste buy way of a tee in the 4" pipework and this has been bought up through the floor in the correct place.

The toilet waste however is directly below position of the toilet making it very tight to get a 4" pipe up above the level of the basin waste for an air admittanace valve.

So can I reduce the pipework size and put an 2" air admittance valve in? Or does anybody have any other suggestions?

It is not possible to adjust the below ground drainage as it is below a block and beam floor, the pitched roof above has an opening window directly above the roof and the wall to side has an office room ajoining it so a vented stack isnt an option.

many thanks


Adam

 

[Ockyvines]

Hi all, Been to veiw a property today that the customer would like a new down stairs cloakroom with shower in. The room has been plastered and first fix of pipework is in and the drainage has been layed below a block and beam floor. The foul drain runs into an open chamber beneath a man hole cover.

The other end (at the moment) is capped off at floor level in the cloakroom. Provision has been made for the shower waste buy way of a tee in the 4" pipework and this has been bought up through the floor in the correct place.

The toilet waste however is directly below position of the toilet making it very tight to get a 4" pipe up above the level of the basin waste for an air admittanace valve.

So can I reduce the pipework size and put an 2" air admittance valve in? Or does anybody have any other suggestions?

It is not possible to adjust the below ground drainage as it is below a block and beam floor, the pitched roof above has an opening window directly above the roof and the wall to side has an office room ajoining it so a vented stack isnt an option.

many thanks


Adam

On new build this is common practice and no air valve is used, just a pan connector into the drain. The trap will not pull because of the small vertical drop into the drain and it will flush fine.

 

[stevetheplumber]

for future reference its a stub stack not sub

 

[sparky]

Oxyvines...So a pan connector straight into the 4 inch soil elbow that then runs to the sewer? No stub stack or vent pipe at all?

 

[arhplumbheat]

No vent at all?

 

[Ockyvines]

No vent at all?

That's right, prob done 600-700 like it on new build over the years

 

[sparky]

I do alot of new build but weve always a stub stack.

 

[arhplumbheat]

Re: Soil stub stack issue

OK so no need for stack at all then.

 

[Plamber]

Would it be possible to fit a pan adaptor with a air inlet?

 

[sparky]

Whats a pan adapter with an air inlet? A pan connector with a comp outlet? Do you need an air inlet?

 

[Plamber]

Thought you could get a pan adaptor with an air inlet of some sorts to reduce the pull. if not........my mistake

 

[sparky]

You probably can just never seen one. Would be interesting to find out though.

 

[arhplumbheat]

I would like to know if there is a pan con with a air valve.

I am going to put in a soil branch with a boss for a basin waste in this case. Also gives me a chance to put another boss in a put an air admittance valve if basin trap gets sucked out buy toilet flush.

 

[Ockyvines]

I would like to know if there is a pan con with a air valve.

I am going to put in a soil branch with a boss for a basin waste in this case. Also gives me a chance to put another boss in a put an air admittance valve if basin trap gets sucked out buy toilet flush.

Hep VO trap on basin will act as air inlet in the unlikely situation that you need it

I do alot of new build but weve always a stub stack.

I have worked for on a couple of new build sites where they have initially asked for it but dropped it when they have grasped the principles of air admittance at low level and the obvious space and money saving that can be achieved.
All you new builders out there who are using stub stacks in ground floor cloakrooms, ask your NHBC or local authority building control officers about it, it is totally unnecessary most all situations