Hi all

Two questions on 40mm washing m/c waste..

Does it matter how high the elbow is that takes the pipe through the wall
(or conversely how long the vertical leg is, if I raise the position of the
elbow).
Is it usual to put a trap of some sort at the bottom of this (my current
install doesn't have one and I don't remember bad smells as a result)?

TIA

Phil

TheScullster
wibbled on Wednesday 30 June 2010 12:27

Hi all

Two questions on 40mm washing m/c waste..

Does it matter how high the elbow is that takes the pipe through the wall
(or conversely how long the vertical leg is, if I raise the position of
the elbow).

Not really, with one proviso: if the elbow is too close to the top of a
standpipe, teh force of the machine emptying can cause "gurgle-back" ie
flooding out the top. Swept bends rather than elbow/knuckle bends help. I
have 12" from top of 40mm pipe to bottom of swept bend, through the wall
then another swept bend and it works fine.

With a sharp knuckle bend I'm fairly sure it would not work.


Is it usual to put a trap of some sort at the bottom of this (my current
install doesn't have one and I don't remember bad smells as a result)?

If it is plumbed into a closed sewer branch, you absolutely *must* have a
trap.

If it goes into a gulley or hopper, you'd survive without but the trap would
help reduce cold draughts in winter.

--
Tim Watts

Managers, politicians and environmentalists: Nature's carbon buffer.

On Jun 30, 12:27*pm, "TheScullster" wrote:
Hi all

Two questions on 40mm washing m/c waste..

Does it matter how high the elbow is that takes the pipe through the wall

too vague, sorry


(or conversely how long the vertical leg is, if I raise the position of the
elbow).
Is it usual to put a trap of some sort at the bottom of this (my current
install doesn't have one and I don't remember bad smells as a result)?

TIA

Phil

A trap is good practice, yes. Machines work without one but you'll get
nasty drain whiffs at times. The trap can be nothing more than
positioning the outlet hose so it dips below the waste pipe.


NT

"Tim Watts" wrote


Hi all

Two questions on 40mm washing m/c waste..

Does it matter how high the elbow is that takes the pipe through the wall
(or conversely how long the vertical leg is, if I raise the position of
the elbow).

Not really, with one proviso: if the elbow is too close to the top of a
standpipe, teh force of the machine emptying can cause "gurgle-back" ie
flooding out the top. Swept bends rather than elbow/knuckle bends help. I
have 12" from top of 40mm pipe to bottom of swept bend, through the wall
then another swept bend and it works fine.

With a sharp knuckle bend I'm fairly sure it would not work.


Is it usual to put a trap of some sort at the bottom of this (my current
install doesn't have one and I don't remember bad smells as a result)?

If it is plumbed into a closed sewer branch, you absolutely *must* have a
trap.

If it goes into a gulley or hopper, you'd survive without but the trap
would
help reduce cold draughts in winter.

--
Tim Watts

Thanks Tim
Just the info I needed.
Discharges into gulley, but gulley connects after short drain run to
combined water/sewer system, so will defo fit trap of some sort!

Phil

TheScullster
wibbled on Wednesday 30 June 2010 16:20


Thanks Tim
Just the info I needed.
Discharges into gulley, but gulley connects after short drain run to
combined water/sewer system, so will defo fit trap of some sort!

The gulley will have a trap underneath too - you can tell by the standing
water under the grate.

As I said, then a trap will help stop draughts and won't do any harm. Trap
doesn't have to be right by the machine - I have mine the other side of the
wall under the stairs for convenience - that type is called a "running
trap".

--
Tim Watts

Managers, politicians and environmentalists: Nature's carbon buffer.