WC Soil Piping needs sorting :-(

[dilalio]

Thanks. 50mm or 110mm AAV then.

I understand that it should be... "at least 200 mm above the highest overflow level of appliances on the soil pipe, usually at the top of the vertical stack, vertically oriented, and in an accessible, ventilated location."

Does that mean it "has" to be at the start of the water flush - behind the WC? - or can it be along the soil pipe close to the WC?

Is the key that is has to be before any strap-on waste connections to sinks or showers? - so it can let air in behind the flush and prevent and vacuum following it?

They allow air in, not out.
So in principle, an AAV at the top of any dead branches. SVPs can be anywhere along the run as they breathe in and out.
Quite often, an anti vac on a basin waste will suffice, but each situation has its own requirements.

 

[dilalio]

In your situation, I'd be building a box with a concealed cistern and back to wall pan and put a stub stack with an AAV inside the cistern box.

 

[advisewelcome]

They allow air in, not out.
So in principle, an AAV at the top of any dead branches. SVPs can be anywhere along the run as they breathe in and out.
Quite often, an anti vac on a basin waste will suffice, but each situation has its own requirements.

Thanks. Yes, agree the anti-vacs might be fine, but we have to lower the stack in the garage (so the shower does not have a huge pedestal) - hence whilst faff'ing with the soil pipe, may as well get an AAV in (putting it in after would be real hassle).

Will reply to your great idea as well with the concealed cistern.

 

[advisewelcome]

In your situation, I'd be building a box with a concealed cistern and back to wall pan and put a stub stack with an AAV inside the cistern box.

Hi, really like your idea (like below pic). But would probs have to throw away the current Wickes Portland reliable WC and then the gubbins to the WC would not be as accessible should there be future leaks. If time and budget permits after the soil piping and shower work - then maybe. Appreciate the idea.

Would really welcome feedback on the soil piping plan as that is the key bit of infrastructure to get done. Will post up a plan..

 

[advisewelcome]

Outline plan below...

-In new shower room the current 110mm pipe would be lowered to the garage floor
-New stud floor flush with the house floor will be put in with shower tray on top
-Will dig up WC room quarry floor and run 110mm pipe up to the WC
-50mm AAV stub stack fitted behind a ventilated stud wall in the Shower room
-Stud wall would hide shower hot / cold feeds (and other historic piping)
-Further stap on connections to shower-room shower & sink wastes can be fitted
-A new WC room sink would also need waste connection to the soil pipe
-Additional anti-siphons solutions can be fitted to the sinks/showers wastes


Welcome feedback:
-Would this outline plan work?
-50mm stub stack be okay behind that wall?
-Should the small hand sink waste connection to the soil pipe be after the AAV to avoid vacums?
-Should I also plumb a 110mm AAV provision to the soil pipe as a precaution in the New WC room? I could just cap it off if not needed

Key questions: Is the 50mm AAV stub stack okay behind that wall and sufficient for this set-up?

 

[endecotp]

What are you going to do when it inevitably blocks at the lower bend and the shower tray fills with “waste”?

 

[advisewelcome]

What are you going to do when it inevitably blocks at the lower bend and the shower tray fills with “waste”?

Hi - lower bend has been there for 40yrs with a WC sitting on top - and no blocks - but I suppose it hasn't had 3 additional wastes (2 sinks and shower) going through it - would that make a difference?

Was thinking of putting a maintenance access hatch in the stud floor to get to the shower wastes (which are on the floor side, not wall side for that reason) - should we be thinking of adding some rodding access into the pipes or something?

The lower bend is 2m-2.5m away from the manhole opening - does that mean the elbow "is" maintenance accessible should blockages occur?

 

[dilalio]

Hi, really like your idea (like below pic). But would probs have to throw away the current Wickes Portland reliable WC and then the gubbins to the WC would not be as accessible should there be future leaks. If time and budget permits after the soil piping and shower work - then maybe. Appreciate the idea.


View attachment 394186

Would really welcome feedback on the soil piping plan as that is the key bit of infrastructure to get done. Will post up a plan..

Buy a cistern with a flush plate then all the gubbins can be changed via that.
As for durgo, get a push fit mcalpine one so that you can lift off the shelf of the boxing and pull it off the top of the stub stack for maintenance.

That's what I'd do.

Sell the old bog on ebay. Someone will buy it.

 

[dilalio]

Hi - lower bend has been there for 40yrs with a WC sitting on top - and no blocks - but I suppose it hasn't had 3 additional wastes (2 sinks and shower) going through it - would that make a difference?

Was thinking of putting a maintenance access hatch in the stud floor to get to the shower wastes (which are on the floor side, not wall side for that reason) - should we be thinking of adding some rodding access into the pipes or something?

The lower bend is 2m-2.5m away from the manhole opening - does that mean the elbow "is" maintenance accessible should blockages occur?

Pipe it properly and it won't block.
Don't put wet wipes down it.
It can always be rodded from the inspection chamber.

 

[dilalio]

But

You're finding problems where they are unlikely. Catastrophising!

 

[advisewelcome]

You're finding problems where they are unlikely. Catastrophising!

....Probably, but don't know what I don't know.


Would really help to know if the below 50mm AAV design is ok in principle?
-Does the AAV need to be behind the WC at the start of the water inlet to prevent the vacuum from following the water?
-Or can the AAV be close to the flush (0.5m away) and do the same job (below diagram)?
-Do all the wastes (sinks and shower) connections have to be after the AAV stub stack?

-I can put an AAV maintenance hatch in the stud wall to get to it (if needed)
-Will save me having to AAV mess around behind the WC as limited space there

Think this is fit for purpose??

 

[dilalio]

I've already told you what I would do.

 

[advisewelcome]

I've already told you what I would do.

Thanks. I think you mentioned a 50mm AAV stub stack behind the WC?

If we had to stick to the current WC, the below kind of arrangement is the way to go...?

Is a AAV stub along the 110mm pipe just not as effective? That option would mean we don't have to disturb the stud wall currently behind the WC

 

[dilalio]

Thanks. I think you mentioned a 50mm AAV stub stack behind the WC?

If we had to stick to the current WC, the below kind of arrangement is the way to go...?


View attachment 394280

Is a AAV stub along the 110mm pipe just not as effective? That option would mean we don't have to disturb the stud wall currently behind the WC

Ever heard the expression...
"buying a dog and barking yourself"?

The way I said to do it is the way I would do it for a customer.
If they had other ideas of their own... I'd still do it and charge them but the onus would be on them!

Back to wall pan,
Boxing or furniture unit,
concealed cistern,
4inch durgo on a stub stack.

Is the proper way to do it.
End of.

 

[advisewelcome]

Back to wall pan,
Boxing or furniture unit,
concealed cistern,
4inch durgo on a stub stack.

Is the proper way to do it.
End of.

OK - will see what can be done. How would the plumbing work to the stub stack?

Where would it branch off and how? Have a link to any plumbing parts that would do the branching? Thnks.