SVP Vs. AAV Vs. Nothing at all??

[Nigel_Cro]

Ok, So I am refitting/refurb'ing a shower room and turning what was a traditional shower into a wet room.

The shower drain is self-contained and has its own access to the external drains, so no problem there.

The toilet and the sink used to both go into a shared waste pipe fitted inside the room in a corner. When I removed all of the old plumbing, the top of the soil pipe was just capped off with a screw cap for access but didn't have any kind of venting.

Having done some research, it appears that it would be better if the soil pipe could be fitted outside and vented to atmosphere, but for a number of reasons, this isn't going to happen. So, I need to consider how to deal with the internal soil pipe.

Firstly, do I actually need an AAV, the toilet waste will join the stack (such as it is) from the side through a 92.5 branch and the sink waste will join the same branch, also from the side. There will be no possibility of a water plug forming on a long drop and sucking the water from the sink trap, or at least I don't think there will.

Secondly, if I do need to fit an AAV, I think that best practice is to fit the AAV so that it is higher than the highest trapped water in the system, this will mean coming above the level of the sink, which will be a real pain as I will have to box it in and allow for access in what will be a fully tiled room. Would it be a disaster if the AAV sat at roughly the same level as the sink trap, maybe even slightly below, which would allow it to finish below the level of the sink and be hidden in the sink cabinet?

Any comments gratefully received, thanks for reading...

Nigel

 

[kevplumb]

View media item 8354

 

[Nigel_Cro]

Thanks Kev,

That's what I thought - bit of a pain, it will really mess up the boxing in and sink cabinet from a tiling and aesthetic perspective.

Maybe I ought to think about going through the wall to an external SVP after all.

From a fluid dynamics perspective, the chances of a vacuum forming behind a water 'plug' has to be next to zero as the flow along the horizontal section won't allow any sort of dynamic seal to form.

But I guess regs is regs.

 

[Hugh Jaleak]

Is it a ground floor room?

 

[Nigel_Cro]

Hi Hugh,

Yup, downstairs room in a modern, single storey, extension.

Thanks for the interest...

Nigel

 

[Hugh Jaleak]

A WC is allowed to be directly connected to the drain provided the distance from the crown of the WC trap to the invert (bottom of the pipe of the drain) is less than 1.3 metres. Some fit a stub stack and AAV but provided there is a vent elsewhere on the property you may not need to ventilate this section. If it worked ok before I doubt it'll be an issue.

 

[Nigel_Cro]

Thanks Hugh,

That is good news - fortunately in this instance the drains are really shallow and the distance between the crown (if I understand what that is correctly) and the invert should be a lot less than 1.3 metres.

I think I may get what height I can on the stub stack, without having to come above the sink cabinet, and plonk an AAV on it - just in case.

Unless for some reason I can't think of this is a REALLY bad idea??

Thanks again,

Nigel

 

[Nigel_Cro]

Thanks Hugh,

That is good news - fortunately in this instance the drains are really shallow and the distance between the crown (if I understand what that is correctly) and the invert should be a lot less than 1.3 metres.

I think I may get what height I can on the stub stack, without having to come above the sink cabinet, and plonk an AAV on it - just in case.

The main stack (external cast iron, with a roof level vent) is right round the other side of the building, although on the same drain run (don't ask, our drains are a horror).

Unless for some reason I can't think of this is a REALLY bad idea??

At least I don't have to reconstruct another inspection pit!

Thanks again,

Nigel

 

[Nigel_Cro]

Double post...

Bl**dy Orange Internet!

Don't ever, ever, ever, ever get internet from Orange!

 

[Hugh Jaleak]

I have Sky Broadband, still get a double post on occasions, think it's the PC rather than the internet connection though. (Or me being impatient!)

If you are worried about the basin trap being pulled, fit an anti vac trap. Try it, if there's an issue, pull the cap out the 110mm tee and extend up to fit AAV. (You'll hear the trap gurgle if there's any 'pull' on it.)

 

[Nigel_Cro]

Thanks again Hugh,

I am waiting for BT to upgrade our road to fibre optic some time this month, then I will tell Orange to go forth and multiply!

The anti-vac trap sounds a great idea.

I don't think there will be a problem because there wasn't before, and there is no long vertical drop, but I don't want to get all this work done and end up with a gurgle!

Off to Screwfix!

Nigel

 

[SandyLyon]

The anti-vac trap sounds a great idea.

Or a HepVo valve

 

[Nigel_Cro]

Oooooh - never used a HepVo before...

Might have to have a look into one of those - I like new toys

 

[SimonH2]

I am waiting for BT to upgrade our road to fibre optic some time this month, then I will tell Orange to go forth and multiply!

Just a FYI ...
While BT Internet are carefully marketing things so as to sound like only they will be offering fibre, it's actually open to all ISPs and BT OpenReach are not allowed to restrict them selling it. In practice it'll work just like with ADSL now - BT OpenReach are responsible for the bit of copper from your house to the exchange (ADSL) or green box (FTTC), but various ISPs rent that bit of copper and sell you a service over it.

BT (the phone company) is not the same as BT OpenReach (who only do the cables), and neither are the same as BT Internet (who provide internet services). BT OpenReach used to be BT, but in the name of competition they are now a separate company and supposedly treat BT the same as every other customer (yeah, and I enjoy watching aerobatics displays by the Porcine Aerobatics Team )

 

[Nigel_Cro]

Thanks Simon,

I knew a lot of that - there would be no point me changing from Orange now as no-one else can give me better speed/width this far from the exchange, hence the reason I am staying with Orange.

But I am sooooooo fed up with Orange 'Customer Service' (yeah right!) I am going to change as a matter of principle once the fibre arrives.

It won't necessarily be to BT, depends who can give me a good deal, but one thing is for sure - it WON'T be bl**dy Orange!!