PeterC
wibbled on Thursday 15 October 2009 19:32

On Thu, 15 Oct 2009 06:43:37 -0700 (PDT), Andy Dingley wrote:

On 15 Oct, 14:08, Tim W wrote:

The only question I have is will they really cope with a wedged lump of
bog paper and 4l of water travelling down the pipe after a bog blockage
as that's quite a lot of suction and air volume?

The HepVO will open during the flush with a mighty rushing wind
through the basin, then close afterwards. HepVOs make excellent AAVs.

Sadly they make poor waste traps. In particular, any sort of foreign
bodies down the basin waste will cause problems. Things that a bottle
trap would happily flush through, or hold onto without problem, will
cause a HepVO to start jamming open. There's no "dead space" in a
HepVO, as there is with a bottle trap, so the smallest particles will
tend to start accumulating blockage-builders - in particular,
washbasin hair.

Personally I'd be very reluctant to use HepVOs again.

The sink on which I fitted one has all sorts of junk down it and hasn't
had a problem for ~7 years, although I can see that something stuck in the
trap would leave it 'open'.
Bottle traps etc. syphon and can lose water due to the wind causing
oscillations and evaporation; also string/fabric/hair can syphon off water
by capillary action.

On balance, I'd rather have HepVO, especially for low throughputs where a
trap might hold muck that putrifies.
Disadvantage: any object accidentally dropped in (earing, false tooth)
ain't gonna be there!

Andy, Peter:

I had wondered whether HepVo's could get nadgered by trapped crap.

I could run the sink into the bath drain, but that takes a different, 5-6m
route to a different stack and I can see globs of toothpaste gradually
settling and bunging that pipe.

Hmm. Two perfectly valid opinions... I might find the sink sucking a gush of
air disconcertings, but the AAVs I've seen make farty sounds so I'm not
sure what's worse...

--
Tim Watts

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