I have a similar situation to JMC - I only have a downstairs toilet
and I want to add an upstairs one.

Unlike JMC, I think my pipe slope should be OK, but I don't appear to
have a "soil stack" visible anywhere outside my house. My mate tells
me I must instead have an "air admittance valve" hidden somewhere near
my current downstairs toilet (either inside the house or outside under
some wooden decking I have). I've never seen it but it definitely
isn't upstairs (I have no loft).

If that is true, will there be a problem with the new upstairs toilet?
Will I have to move this "air admittance valve" to be higher than the
new highest toilet, i.e. the upstairs one?

Does the answer to this depend on whether I have a proper bog or a
pumper?

THank You.

Bigus Dicus wrote:

I have a similar situation to JMC - I only have a downstairs toilet
and I want to add an upstairs one.

Unlike JMC, I think my pipe slope should be OK, but I don't appear to
have a "soil stack" visible anywhere outside my house. My mate tells
me I must instead have an "air admittance valve" hidden somewhere near
my current downstairs toilet (either inside the house or outside under
some wooden decking I have). I've never seen it but it definitely
isn't upstairs (I have no loft).

If that is true, will there be a problem with the new upstairs toilet?
Will I have to move this "air admittance valve" to be higher than the
new highest toilet, i.e. the upstairs one?



Yes, probably.

In essence you need to have a pressure relief system that will carry the
pongs away high up SOMEWHERE in the sewer. This may or may not be shared
between houses, and it may or may not be visible. In my case I have
carried a long exhaust pipe down the length of the roof to exit under
the eaves.

Each toilet then needs some way to ensure that as it flushes, the
suction of the falling turd and water mix does not suck dry any basin
traps etc. That is the purpose of the air admittance valve.

So you need an open exhaust somewhere downstream of every bog to prevent
pressure build up, and an inlet somewhat upstream of it, to stop partial
vacuums.

Air admittance valves do the latter, but not the former.



Does the answer to this depend on whether I have a proper bog or a
pumper?

THank You.

The Natural Philosopher wrote:

In essence you need to have a pressure relief system that will carry the
pongs away high up SOMEWHERE in the sewer. This may or may not be shared
between houses, and it may or may not be visible. In my case I have
carried a long exhaust pipe down the length of the roof to exit under
the eaves.

Each toilet then needs some way to ensure that as it flushes, the
suction of the falling turd and water mix does not suck dry any basin
traps etc. That is the purpose of the air admittance valve.

So you need an open exhaust somewhere downstream of every bog to prevent
pressure build up, and an inlet somewhat upstream of it, to stop partial
vacuums.


Are you sure about this? This wasn't my understanding at all. The air
admittance valve/partial vacuum thing, yes, definitely. Pressure build
up? Where is the pressure building up and why? Sewers aren't airtight.

I've seen lots of systems with an air admittance valve and nothing else.

Please expand.

--
Grunff

"Grunff" wrote in message
...
The Natural Philosopher wrote:

In essence you need to have a pressure relief system that will carry the
pongs away high up SOMEWHERE in the sewer. This may or may not be shared
between houses, and it may or may not be visible. In my case I have
carried a long exhaust pipe down the length of the roof to exit under
the eaves.

Each toilet then needs some way to ensure that as it flushes, the
suction of the falling turd and water mix does not suck dry any basin
traps etc. That is the purpose of the air admittance valve.

So you need an open exhaust somewhere downstream of every bog to prevent
pressure build up, and an inlet somewhat upstream of it, to stop partial
vacuums.


Are you sure about this? This wasn't my understanding at all. The air
admittance valve/partial vacuum thing, yes, definitely. Pressure build
up? Where is the pressure building up and why? Sewers aren't airtight.

I've seen lots of systems with an air admittance valve and nothing else.

Please expand.

Doesn't every 3rd house or so on a sewer run have to allow air in through a
stench pipe?
I'm at the end of a cul-de-sac of 5 houses built in 1980. My house has a
"stench" pipe through the roof which I wanted to replace with air admittance
valve but was advised not to do so but it would be ok for my neighbour to
this.

Grunff wrote:

The Natural Philosopher wrote:

In essence you need to have a pressure relief system that will carry
the pongs away high up SOMEWHERE in the sewer. This may or may not be
shared between houses, and it may or may not be visible. In my case I
have carried a long exhaust pipe down the length of the roof to exit
under the eaves.

Each toilet then needs some way to ensure that as it flushes, the
suction of the falling turd and water mix does not suck dry any basin
traps etc. That is the purpose of the air admittance valve.

So you need an open exhaust somewhere downstream of every bog to
prevent pressure build up, and an inlet somewhat upstream of it, to
stop partial vacuums.



Are you sure about this? This wasn't my understanding at all. The air
admittance valve/partial vacuum thing, yes, definitely. Pressure build
up? Where is the pressure building up and why? Sewers aren't airtight.



That becuase thay have specail vents to prevent pressure build up.

See your building regs.


Apart from that they are pressure tested to make sure they ARE airtight.


I've seen lots of systems with an air admittance valve and nothing else.

Please expand.

So you need an open exhaust somewhere downstream of every bog to prevent
pressure build up, and an inlet somewhat upstream of it, to stop partial
vacuums.

Thanks, but I am still a bit confused. If I currently have just one
bog, dowstairs, and no soil stack open exhaust above my roof, then
presumably:

(a) I have an AAV somewhere in my downstairs bathroom that services
only that bog (I am not allowed to take the floorboards up at present
as the M-I-L is coming to stay)

(b) Somewhere downstream of my bog there is an open exhaust, although
this may be to service multiple bogs in my and my neighbours' houses?

So if I put the new upstairs bog in, I will definitely need another
(a) dedicated to the new bog, but the same (b) can service (perhaps)
both the new and the old bog, as well as neighbours' bogs?

Please advise - I am VERY confused!
Thanks...

"Bigus Dicus" wrote in message
m...
So you need an open exhaust somewhere downstream of every bog to prevent
pressure build up, and an inlet somewhat upstream of it, to stop partial
vacuums.

Thanks, but I am still a bit confused. If I currently have just one
bog, dowstairs, and no soil stack open exhaust above my roof, then
presumably:

(a) I have an AAV somewhere in my downstairs bathroom that services
only that bog (I am not allowed to take the floorboards up at present
as the M-I-L is coming to stay)

(b) Somewhere downstream of my bog there is an open exhaust, although
this may be to service multiple bogs in my and my neighbours' houses?

So if I put the new upstairs bog in, I will definitely need another
(a) dedicated to the new bog, but the same (b) can service (perhaps)
both the new and the old bog, as well as neighbours' bogs?

Please advise - I am VERY confused!
Thanks...

Sorry I haven't been following the thread, but the jist of the problem is installing
another loo in an upstairs room (?) correct. This would depend on where the new loo
would be sited to correspond with the original downstairs loo and where the pipework,
mainly, for the waste extraction.

Do you have an internal soil stack built in to a corner or behind the plasterwork in
the original loo ? Have a look to see where the pipe from the back of the existing
loo goes and from there you should be able work out where the soil pipe is in relation
to the walls. Does the loo pipe go directly through the wall to the outside. Does it
bend and go into a boxed in soil stack in the corner of the room ? Does it disappear
through the floor ? When you flush the loo, can you hear the flowing passed in
another room beside the loo ?

Once you find out where the existing soil goes you're on your way to being able to
makes plans for the new loo. You don't even have to use the existing soil stack pipe
if you find out where the sewerage system is in respect to you property. It might be
possible, or even easier, to take a new soil pipe from the new loo directly to the
sewer system near you house. The pipes are cheap to buy, it's the fitting that cost a
bit more in terms of drilling and digging and things.

On 13 May 2004 01:41:31 -0700, a particular chimpanzee named
(Bigus Dicus) randomly hit the keyboard and
produced:

I only have a downstairs toilet
and I want to add an upstairs one.

If you only have appliances on the ground floor, and you are in a
terrace or close to other houses on a sewer, then you may not have a
vent at all. It is acceptable to run a WC (and other fittings) less
than 1.5m above the invert into a vented sewer provided the branch is
less than 6m long.

If this is the case, then, yes, you would require a new soil stack to
the first floor. This could be vented with an air-admittance valve
internally. Provided you keep your downstairs WC, you can add a
pumped one to the first floor (subject to Peter Parry's approval).
--
Hugo Nebula
"The fact that no-one on the internet wants a piece of this
shows you just how far you've strayed from the pack".