DIYer - need help with toilet pipe air-valve install

[pc__upf]

Hi,

New to the forum - hoping to get some help here.

I am rerouting my toilet to have the pipe work hidden in the eaves.

Bath/shower/basin waste connects to the toilet drain via Barco Bos.

I need help with the air vent.
- Do I need one for toilet, and another for shower/bath/basin waste?
- Do I need one for each bath, basin and shower?

Where is the best location for the air valve (or valves)?

Many thanks for your help.

 

[pc__upf]

The 40mm waste pipe will pull any water filled traps on the all the fittings when the bath is drained Part H of the building regs sets out the maximum runs for single runs to single fittings once you start combining them then you need to increase the waste pipe size or add an anti-siphon pipe or mini AAAV or replace the water filled traps with waterless traps.
The stack should be ventilated, the branch to the WC doesn't have to be but I would be tempted to run a 50mm anti picking up the WC & the bath (40 or even 32mm) if at all possible, run above overspill level of the pan & connected back into the dry part of the stack (vent pipe). In that way no mechanical devices would be required.
Medium radius bends are fine so long as the float is installed with the correct falls (18 - 90mm per M) de-bur the pipes & you will not have any problems.
https://assets.publishing.service.g...achment_data/file/442889/BR_PDF_AD_H_2015.pdf

@ChrisWatkins - many thanks, very helpful.

Is this what you mean?

 

[chris watkins]

@ChrisWatkins - many thanks, very helpful.

Is this what you mean?

View attachment 38193

No, you don't need & probably shouldn't have a "Durgo" on the main stack, can't terminate to atmosphere ? if it can then the loop is find but not essential it is more to try to anti the bath run so it will not self-syphon when discharged. Otherwise couldn't you run it separately along the eaves to connect directly to the stack?
Remember this work is covered by Building Control & you should be talking to them.
Please don't use anti-vac traps you may well live to regret it.
Try this type of trap = Sanitary waste valve in bathroom applications

 

[pc__upf]

Thanks Chris,

With a waterless trap I can now reroute the bath and connect directly to the toilet's 4 in. (See diagram) because it can go above joists.



This ok?
https://www.NoLinkingToThis/p/osma-...qAosAERuxAzb8d-yeEAaAmbpEALw_wcB&gclsrc=aw.ds


About the AAV - should it go on the 4 in behind the toilet, or the shower/basin 1.5 in?

 

[Riley]

Are you running the shower waste through joists

 

[pc__upf]

It was like that when we bought the house.

 

[Coby kenny AGUILAR]

Thanks Chris,

With a waterless trap I can now reroute the bath and connect directly to the toilet's 4 in. (See diagram) because it can go above joists.

View attachment 38194

This ok?
https://www.NoLinkingToThis/p/osma-...qAosAERuxAzb8d-yeEAaAmbpEALw_wcB&gclsrc=aw.ds


About the AAV - should it go on the 4 in behind the toilet, or the shower/basin 1.5 in?

You've got the right idea now,

Waterless traps are great but put them where they're accessible, anything compression should have access.

The 'outside pipe' should tee up above the roof if you're unable to do this and have a boxing or void behind the pan / toilet, take it up as far as you can go or same height as the Cistern and put a durgo on it

 

[Riley]

It was like that when we bought the house.

Doesn’t make it right though. Weakened joists and all that

 

[chris watkins]

The bath connection is the main problem one for siphonage because of both the volume of water & how quickly it discharges. Not so with the shower because the water flow is much slower & there is normally water draining away slowly after the shower is off, this will refill a water trap even if the seal is lost.
All waste connections to 110mm soil pipes should ideally be made either in a vertical section or on top of a horizontal (it is normally taken that only the bottom 2/3rd of the pipe will be wet) but you will need to take care if you are close to the back of the pan because the solids may not be fully broken up & there could be splashing as the water leaves the Pan.
You may wish to put a small (40mm) AAAV (Durgo) on the basin run, put it up as high as you can under the counter on the 40mm tee & run 40mm float only reducing to 32mm as you come across to each basin trap.

 

[chris watkins]

I am still concerned that you may not be venting the stack, can you get the vertical stack outside to vent correctly to atmosphere?
Will this be the only vent on your drainage system?
By Law the head of the run must be vented !!!

 

[pc__upf]

Chris, thanks so much for all this.

This is not the main drainage system of the house. This is literally just this one bathroom, which was added by the previous owners.


Latest:
1) AAV added to 4 in pipe behind wall.
2) Bath (with waterless trap) connects to toilet's 4 in behind wall with boss connector (see link below). May connect at exactly half line due to slope. Problem?
3) Waterless trap on bath and one on each basin (or one shared)
4) Normal trap under shower (no access)
5) 40mm AAV on the way out of both basins (confirm location-diagram)

Questions :
1) For two basins, should I install one waterless trap on each, or can they share one after a tee? (the tee can be the AAV?)
2) If using waterless traps, the syphoning may not be a problem any more. If joining bath waste to 4 in pipe too close to toilet is a concern, can the bath waste return to the original path and join the shower pipe?
3) Don't know what a 40mm float is.

Here's the shopping list so far : Please recommend alternatives if these are bad for any reason.

110mm AAV (Durgo) : https://www.NoLinkingToThis/p/floplast-ax110g-air-admittance-valve-grey/47962

40mm AAV for basin: https://www.NoLinkingToThis/p/floplast-af32w-air-admittance-valve/42968

Boss Connector : Water Waste BIG BOSS Pipe Adaptor - 40mm - 1.1/2"- Black - Pipe & Fittings | BES.co.uk-19871 | BES.co.uk

Waterless trap: https://www.NoLinkingToThis/p/osma-waste-valve-white-x/1819K

 

[chris watkins]

There are so many variations & options without being on site I can't go any further than the comments below against yours in red.

View attachment 38226 View attachment 38227
Latest:
1) AAV added to 4 in pipe behind wall. Building Control may allow a AAAV valve to be installed behind the WC in the void so long as it is above the overspill level of the pan & accessible.
2) Bath (with waterless trap) connects to toilet's 4 in behind wall with boss connector (see link below). May connect at exactly half line due to slope. Problem? May be OK but would need to see in relation to pan outlet. Can't you run it further along the void before connecting?
3) Waterless trap on bath and one on each basin (or one shared) I would definitely fit one to the bath, as this is the problem appliance.
4) Normal trap under shower (no access) If this is to remain a water filled trap don't connect the bath waste to it as it will pull the shower trap when it is discharged.
5) 40mm AAV on the way out of both basins (confirm location-diagram)

Questions :
1) For two basins, should I install one waterless trap on each, or can they share one after a tee? (the tee can be the AAV?) A cross tee is not a common fitting so I would have a vertical pipe in either of the corners of the vanity unit with a 40mm tee & an access on the vertical end with a 40mm float (see below) running across with 40mm tees with a 40x32mm reducer picking up each basin. You could either have normal P traps on each & off the end of the float have a vertical rise to get you up as high as you can within the unit & put a mini AAAV to allow air in & break any siphonage that may occur. The other option is just fit a 40mm waterless trap on the vertical drop in the corner.
2) If using waterless traps, the syphoning may not be a problem any more. If joining bath waste to 4 in pipe too close to toilet is a concern, can the bath waste return to the original path and join the shower pipe? Not recommended see above
3) Don't know what a 40mm float is. Horizontal run of pipe connecting appliances in a line, as in your basins.

Here's the shopping list so far : Please recommend alternatives if these are bad for any reason.

110mm AAV (Durgo) : https://www.NoLinkingToThis/p/floplast-ax110g-air-admittance-valve-grey/47962
40mm AAV for basin: https://www.NoLinkingToThis/p/floplast-af32w-air-admittance-valve/42968
Boss Connector : Water Waste BIG BOSS Pipe Adaptor - 40mm - 1.1/2"- Black - Pipe & Fittings | BES.co.uk-19871 | BES.co.uk
I don't like these & would always try to use a 110mm boss pipe to connect waste to soil pipe, if not possible then a strap-on but these (IMHO) are fine for connecting a condensate waste to an existing stack externally but lack the strength effect the bore.
Waterless trap: https://www.NoLinkingToThis/p/osma-waste-valve-white-x/1819K
Don't forget you will need the adapters for one end if you are not going straight onto an appliance.

Best of luck pc_upf

 

[pc__upf]

There are so many variations & options without being on site I can't go any further than the comments below against yours in red.

Best of luck pc_upf

Can't thank you enough Chris (and all the others) for your help. It's been great!

 

[Gasinspect]

Wouldn't be happy with this. How about a corner toilet, or move onto side wall and straight out? With the low water content toilets even ours doesn't clear every time and that is straight out.

 

[Trotter31]

I would seriously consider getting a professional in, to redesign the whole setup and install for you.

 

[pc__upf]

Some professionals show up and some don't. Some of those who show up never come back. And some who promise to come back and provide a quote for the work, never end up providing a quote because they're taking the girlfriends to New York (true story). The best help I've received so far has been on this forum.

 

[Trotter31]

What part of the country are you in?
There will probably be someone on the forum, who is in your neck of the woods.

 

[pc__upf]

For sure. But I'm a bit tired of calling, waiting, calling again and so on. My trusted plumber has resurfaced after 8 weeks of voice messages and texts. Eight!!!!! He promised a call after Easter. I'll report back.