Air admittence valve - get away with 50mm?

[Tim W]

I have a 4m 110 soil pipe running from a centre bathroom under the floor to a chamber outside. The next chamber along (top end of drains) is open vented correctly.

In the bathroom, I will be connecting the sink into the toilet pipe.

Bog+sink into 110mm pipe. It clearly needs an air valve but I'd like to check a couple of things:

Might I get away with a 50mm jobbie, like:

'm not worried about being "by the book", just whether it's likely to work).

Otherwise if I have to use a 110mm version, does it need to be installed above the flood level (so above the bog rim I suppose) or can it be installed lower? The 50mm one above suggests 100mm above pipes and below flood level.

It will be plugging into the top of one of these:

goes in the side port and the sink goes into one of the small side bosses.

Sorry if this is dumb - never used an AAV before...

Ta

Tim

[Doctor Drivel]

Fit a HepVo trap on the basin. A dry trap that si also an AAV. Simple.

do them, available in most pro plumbing places.

[Rick Hughes]

agree on that a HepVo meets requirements for an AAV

Venting is not to let gas out ... but to let air in to prevent vacuum emptying of traps.

I used HepVo throughout the house anyway, so no issue with venting or emptying.

[Tim W]

Rick Hughes wibbled on Thursday 15 October 2009 12:41

Thank you both :) Those look

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? I presume, the air would get sucked in the sink drain (or overflow if the plug's in)?

How do you mount those - horizontal or vertical?

They do look interesting...

Cheers

Tim

[Man at B&Q]

Strictly speaking, flood level will be the sink rim unless it is lower than the bog rim.

MBQ

[Andy Dingley]

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.

[PeterC]

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!

[Tim W]

PeterC wibbled on Thursday 15 October 2009 19:32

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 W]

Tim W wibbled on Thursday 15 October 2009 20:48

Zombie mode off: I meant to say, exactly the sort of crap that might give the HepVo grief...

[Rick Hughes]

I agree if you drop anything down there - it's gone.

We have HepVo on 6 sinks & on 2 showers and 2 baths - not had a problem with any. Although once a year we pour some drain clearer down each one just to keep them functioning correctly.

Only slight issue is on showers ... I would recommend that you use top opening wastes .. the ones I have, the centre opens, and then you lift out a black sieve that has trapped all the hair that ends up in waste.

[Tim W]

Tim W wibbled on Thursday 15 October 2009 14:08

Anyone?

Just in case I do use one somewhere...

Ta

Tim

[PeterC]

Either way (assuming HepVO). It has to be the correct way up when anything but vertical, so that the sleeve flops down.

See:

[Rod]

They used to have a good installation PDF. That included vertical and horizontal - and indeed I have two horizontal (bath and basin) and one vertical (basin). But I can't locate it in my quick browse. I think they also had examples at angles between. Well worth trying to find if you are considering using them.

All three work fine for us though I have had to clean out the vertical basin one. (But by being mounted vertically within its very small cupboard, it is very easy to take out, clean out and refit. Had I used a conventional trap, or a horizontal installation, it would have been much less convenient.)

I also used their flexible waste on the two basins and that was really nice and easy to use.

[Rick Hughes]

Never heard any of the HepVo traps make a noise ... they just work.

[Rick Hughes]

anyway you want .... there is a line on them that has to be on underside if fitted horizontal.

They come in 2 sizes, plus you can get 90 degree waste adapters to screw onto the end ... I used these on Shower trays to avoid any clearance issues.

[Doctor Drivel]

Hepworth say they can be fitted horizontally. it is best to fit them as vertical as possible if you can and only as a last resort fit horizontally.

[Tim W]

Rick Hughes wibbled on Tuesday 20 October 2009 14:47

Ta - I've filed that to the brain cells

[Tim W]

Tim W wibbled on Thursday 15 October 2009 11:11

OK - I got a Floplast 32/40/50 mm one. A highly scientific mouth suck test shows it seems to allow loads of air through and its operation is silient (no farty noises) other than a hiss.

We'll see how well it works in reality.

Ta

Tim

[A.Lee]

What adaptor did you use to plug the 50mm AAV into the 110mm downpipe? I'm just doing a bathroom where it would be nice to have the AAV below toilet pan level, rather than above it. Ta Alan.

[Tim W]

A.Lee wibbled on Friday 23 October 2009 07:27

13005

Which is either a Floplast SP95:

very similar (haven't got it yet but used ones like it before).

You'll need one of these:

seal the pipe. The AAV is actually 32mm, but comes with an adaptor to 40 and 50mm. I'll put mine up a bit on 40mm, but if you were plugging it straight in, I guess use the 32mm rubber.

B&Q do Marley 110-50mm solvent weld reducers if you prefer (but it's probably better to be able to unplug the AAV for servicing).

Cheers