How close dose a toilet need to be to a Soil Vent Pipe?

[glock339]

How close dose a toilet need to be to a Soil Vent Pipe to prevent siphoning of the U bend? I've Google'd this but can't seem to find the answer.

I have a big problem positioning a soil vent on the outside wall to the toilet so was wondering if it could be Teed in a bit further down the run of pipe and if so how far would be the max? Or dose the vent need to come in rite next to the toilet to allow air in there & the prevent siphoning?

Cheers

 

[Hufty]

Building Regs Part H for the details: www.planningportal.gov.uk/uploads/br/BR_PDF_ADH_2002.pdf

Table 2 gives the max length of a soil branch as 15m. That is of course 15m of unventilated pipe between the toilet and the downpipe/upvent tee. I can't think why it would be different if you offset your vent and downpipe rather than have them in line, although it may look a bit funny.

So if your pipe is only a few metres and there's no way to do it "normally" I'd go for it.

 

[libby lou lou]

The angle that you run it at, is more important than the lenght, ( there is a limit), can't remember the angle, but too steep, and the solids gets left behind.

 

[Hufty]

Good point. I think the self-cleaning angle is 2.5deg for soil pipe which is why most branch fittings are 87.5deg (or 92.5). Basically it's not so much off horizontal, and as long as you don't go old-skool and buy a 135deg branch you should be okay.

 

[Agile]

I think that its normally described as about 1:40 which might be the same angle or rather less.

One of the colleges had a section of transparent pipe which could be adjusted for the fall and could demonstrate how solids are left behing if the angle is too STEEP!

Tony

 

[WabbitPoo]

What did the college use as "soilds" for such a demonstration?

 

[Nige F]

4 moleskins

 

[Richard C]

Table 2 gives the max length of a soil branch as 15m.

Think you'll find the 15 meters given in table 2 refers to unvented branch pipes; for unvented connections to a vented stack, the max length is 6 meters for a single w/c - see diagram 3 below table 2.

 

[glock339]

Thanks for all the replies

I can defo have it within 6 meters so happy days!

Cheers for the link to the regs PDF as well, very useful