No, an admittance valve is fitted on a stack above the toilet.
You don't have a stack to fit it on.
There has to be a vent somewhere on the drain.
On older properties they used to put a pipe approx 4' high, near the manhole
cover, which had some sort of flap in it. Over the years these pipes can get
blocked or even removed by people who don't understand their function.
My outside loo - built over 100 years ago - has no vent, it goes direct
to the manhole. The inside loo has a normal vent, and there's also one
just under the front window. Dunno how that works without letting smells
*The colder the X-ray table, the more of your body is required on it *
Dave Plowman firstname.lastname@example.org London SW 12
Everyone is going for the suction option. But that would only lower
the level an inch or so below the top of the trap. Once you get a
reasonable gap you need *a lot* of suction to pull more water out of
the bottom of the bend. I think you'd notice that level of suction
when it was full, by the noise of glugging...
Is there any heating in this loo? Think of another property of water
evaporation... This would explain how the bend could become "nearly
Dave. pam is missing e-mail
That would be my thought too. I have a couple of places that stand empty for
extended periods and one of the jobs I have to do when I go in is to flush
the loos and run taps, to fill up the various traps again.
You don't have a crack in the porcelain, do you? Everyone (almost) seems
(understandably) to have focussed on pressures - but if the level goes
right down I can't think of anything but a leak of some sort.
That occurred to me too, but I assumed Op would have noticed smelly water on
But maybe its leaking unseen underneath the pan and seeping through
I have seen this in an old house .....
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