I want to cap my waste stack with an air admittance valve, so
I can run my bathroom flue through the old pipe out through
I'm not clear what height I can cap it at though. It runs
though a utility room containing the boiler, and the stack
is joined by a toilet waste and a sink waste, close to the
ground. Can I cap it
a) Whereever I like (preferably about as low as p
b) Above the drain outlet of the boiler
c) Somewhere else
I gather it's supposed to be above the "flood level" of
the room, but I'm not clear what that is, particularly
given that this is a first floor flat...
There are only two types of AAV. Ones that are stuck open and stinking
the place out, or those that are stuck closed leading to Jobbies Not
Going Away. If you haven't got one of these infernal devices, on no
account fit one.
Mind you they do give me the chance to say "It's yer Durgo, missus."
It's the flood level of the appliances, not the room IIRC. As far as I can
tell, the idea is that if you filled all the drains up completely with
water, it should pour out of somewhere below the AAV.
It's not to do with flooding in the 'Environment Agency' sense.
HepVO traps are not so much fitted with integral AAVs, more they actually
are AAVs themselves. I have cut our stack pipe down and have bath, basin
and WC in first floor bathroom working perfectly well. And another WC and
basin in the downstairs cloakroom also on the same stack. (Indeed, the bath
empties at an almost frightening speed now.)
Brilliant devices. Hepworths were also very helpful with advice when I rang
them before deciding on this route.
HepVo traps are not like normal wastes they do not use water as a seal ...
and the design allows easy air ingress which is what you want to vent SV
stacks ... it is not a question of allowing air to escape - the opposite,
you want air to get in when a WC is flushed to avoid negative pressure.
It's this negative pressure that causes the problem ... it sucks water out
On Sat, 20 Dec 2003 20:17:02 +0000 (UTC), "Rick Hughes"
I never suggested it was about allowing air to escape.
Indeed. If there are no traps to suck, the bog doesn't flush properly.
If the HepVo doesn't use a water seal, what does it use, some
mechanical device? Hopefully more reliable than an AAV.
Actually there is another issue related to a stackless system. The
stack may be used to vent the drainage system or septic tank where
used, doing away with the stack can lead to smell problems.
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