Hi guys

our bungalow ("L"-shaped) has a nuisance soil stack (stench pipe)
situated in the back, in the inside corner of the "L". Currently it's
made of cast iron, looks grotty,and is a pain, as the guttering is
squeezed behind the angle where it goes up.

I know it's possible to replace it with a straight pipe, which enters
the eaves, and vents through a chimmney in the roof (replacing a
tile).

However, since the purpose of the pipe is to admit air (to prevent
siphonage), is it possible to fit a new shorter pipe, with an air-
admittance only valve ? I'm sure I've seen one advertised ...

thanks in advance

Jethro wrote:
our bungalow ("L"-shaped) has a nuisance soil stack (stench pipe)
situated in the back, in the inside corner of the "L". Currently it's
made of cast iron, looks grotty,and is a pain, as the guttering is
squeezed behind the angle where it goes up.

I know it's possible to replace it with a straight pipe, which enters
the eaves, and vents through a chimmney in the roof (replacing a
tile).

However, since the purpose of the pipe is to admit air (to prevent
siphonage), is it possible to fit a new shorter pipe, with an air-
admittance only valve ? I'm sure I've seen one advertised ...

It's not only to admit air - the stack pipe also has the function of
venting the sewer. Building control like to see a vent every few houses.

Jethro coughed up some electrons that declared:

Hi guys

our bungalow ("L"-shaped) has a nuisance soil stack (stench pipe)
situated in the back, in the inside corner of the "L". Currently it's
made of cast iron, looks grotty,and is a pain, as the guttering is
squeezed behind the angle where it goes up.

Having just done one, you can certainly tweak it out more - two 135 degree
solvent bends to swan the pipe out can clear the gutter by quite a wide
margin. Solvent weld ensures the free standing bit of 1m ish dangly pipe
can be sufficiently supported by the clips below it down the wall.

You can do the vent pipe in 82mm too - black PVC looks fairly smart.


I know it's possible to replace it with a straight pipe, which enters
the eaves, and vents through a chimmney in the roof (replacing a
tile).


Yes - I used to have one like this.


However, since the purpose of the pipe is to admit air (to prevent
siphonage), is it possible to fit a new shorter pipe, with an air-
admittance only valve ? I'm sure I've seen one advertised ...


No - you need to be able to vent positive pressure too.

Building regs say vent is =3m from all openings *or* 900mm above the tops
of those openings that are closer than 3m.


Cheers

Tim

Jim wrote:
Jethro wrote:
our bungalow ("L"-shaped) has a nuisance soil stack (stench pipe)
situated in the back, in the inside corner of the "L". Currently it's
made of cast iron, looks grotty,and is a pain, as the guttering is
squeezed behind the angle where it goes up.

I know it's possible to replace it with a straight pipe, which enters
the eaves, and vents through a chimmney in the roof (replacing a
tile).

However, since the purpose of the pipe is to admit air (to prevent
siphonage), is it possible to fit a new shorter pipe, with an air-
admittance only valve ? I'm sure I've seen one advertised ...

It's not only to admit air - the stack pipe also has the function of
venting the sewer. Building control like to see a vent every few houses.

Yes that's one of the specific regs: if next door has a vented stack
you're probably OK. Also you can't be the last property at the end of a
row (eg cul-de-sac) so that your AAV valve is at the blind end of the
drainage system.

David

On Mon, 29 Jun 2009 04:51:44 -0700 (PDT), a certain chimpanzee, Jethro
randomly hit a keyboard and produced:

our bungalow ("L"-shaped) has a nuisance soil stack (stench pipe)
situated in the back, in the inside corner of the "L". Currently it's
made of cast iron, looks grotty,and is a pain, as the guttering is
squeezed behind the angle where it goes up.

I know it's possible to replace it with a straight pipe, which enters
the eaves, and vents through a chimmney in the roof (replacing a
tile).

However, since the purpose of the pipe is to admit air (to prevent
siphonage), is it possible to fit a new shorter pipe, with an air-
admittance only valve ? I'm sure I've seen one advertised ...

You can't mount it externally.
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Hugo Nebula
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