Confused by soil stack and branch connections

[Bob Hill]

Hi all,

I've just started the above ground discharge section of my level 2 NVQ and am confused by soil stacks and branch connections (the text book doesn't give nearly enough info, just two bad diagrammes).

I've tried searching the forums but no luck.

My issue is with branch connections into soil stacks and cross flow.

According to the building regs part H page 8 - The ways to prevent cross flow are:

- Have connections at the same level but coming in at least at right angles to each other when looked at from above.

- Have the connections offset with regards to the height they enter the stack (variable distance based on stack diameter and what the branches serve).

- Create a parallel junction of at least 50mm so that the branch connects outside the no connection zone

My questions are therefore:

Are there other methods?
How does the angle that the pipe enters the stack at affect things?

Thanks in advance.

 

[WHPES]

It says somewhere in the regs that junctions should be at 200mm intervals at a minimum.

The steeper the angle, the less likely any backflow.

 

[Masood]

The JTL book is pretty detailed on this. WHPES is right about the 200mm minimum intervals, although I don't remember anything about intervals being variable according to pipe diameter. Not saying you're wrong, but I don't recall seeing it anywhere. Will check the book when I get a chance...

 

[kay-jay]

Only the methods in the regs are approved.
Iirc there are diagrams within doc h which highlight the approved methods.
As masood states the JTL books are also good for trainees as it gets the point across in an understandable way. Other books can overcomplicate simple issues.
Good luck

Sent from my GT-I9100 using Tapatalk 2

 

[Bob Hill]

Thanks guys.

I have the JTL book, which is usually pretty good but on this occasion it just gives two pictures with no explanation.

Do people recall if it used to be different. I've seen council flats with two branches joining directly opposite but the last part of each branch is made up of two 45% bends.

 

[chris watkins]

Manufactures guides are a very good source of information it is worth looking through their sites. Have a look at this one from osma (it is after the fittings part but also have a look at manifolds)
http://www.plumbed-in.com/siteuploads/downloads/09112011173042_1.pdf