aav

[randomrob69]

hi
just wondered if anyone knows if i will need to fit an aav onto my new toilet installation,
I will be installing a new wc in a room that does not have an external wall, the length of 110mm pipe will be,

2.5m with 90degree turn, 1m with 90degree turn, 1.2m with 135 degree turn then .8m to soil stack. There is a total drop of about 1m.

I think the regs say that you need to have a max of 6m of waste pipe before the soil stack but just wondered if the distance and amount of bends would cause problems with syphoning the water out of the trap or causing blockages?
Hope this makes sense and any info would be gratefully received.

 

[AdamAnt]

Whether you need an open vent or can make do with an AAV depends on your existing venting arrangements, so please provide more information.

And which "regs" are you referring to?

 

[seco services]

whats the bco told you they want ?

 

[Richard C]

hi
just wondered if anyone knows if i will need to fit an aav onto my new toilet installation,
I will be installing a new wc in a room that does not have an external wall,

Are you aware the work you’re doing is notifyable, subject to inspection & must comply with Building Regulations on drainage, ventilation, electrics (if a shower/bath is involved) & possible sound insulation; how do you propose to provide forced extract ventilation?

the length of 110mm pipe will be, 2.5m with 90degree turn, 1m with 90degree turn, 1.2m with 135 degree turn then .8m to soil stack. There is a total drop of about 1m. I think the regs say that you need to have a max of 6m of waste pipe before the soil stack but just wondered if the distance and amount of bends would cause problems with syphoning the water out of the trap or causing blockages?

Max length for unvented branch is specified at 6m for single w/c so you’re within limits & should not require an AAAV; but what you’re doing is far from ideal, how/where are you running the 110mm from the w/c. As already pointed out, there are also restrictions with regard to fitting AAAV’s.

All sections of the run at change of direction must have rodding access to from one end or the other; you’re allowed one 45 degree bend. Stick within the recommended fall for the pipe run to the stack; if you make it too steep, the water will run away too quickly, lead to blockages & then you will need that rodding access!

Assuming you will also have a sink & possibly a shower, how are you connecting the remaining wastes? These should, ideally, have separate connections to the stack; if not you will require anti siphon traps or an air admittance valve on the waste run or you will continually draw the traps when the w/c is flushed.

 

[randomrob69]

Thanks for the quick replies everyone, I've not spoken with the bco's yet as i am hoping to get everything planned out beforehand just to make sure its worth going ahead with.

The existing external soil stack is ventilated .
All the bends on the waste pipe will be accessible so will have access for rodding.
Ventilation will be provided through an extractor fan installed in the ceiling running the hose along the attic and out the soffit.

I am hoping to install bath and sink aswell and they will have 32mm(sink) and 40mm(bath) pipes, both these will join a 50mm pipe (2.5m distance) which i would like to join the 110mm wc waste pipe via 50mm boss adaptor. They will be fitted with anti syphon traps.
This is flexible as it will be possible to connect the separate wastes to the main soil stack if required although the runs will roughly be the same length as the 110mm run from previous post.

I hope this can give you a better picture of what i'm planning and any feedback will be gratefully received from you.
thanks
rob

 

[Richard C]

A picky would be good but it sounds viable. Bends should be avoided in the 110mm soil pipe but there appears to be no limit for one w/c but your route seems rather contorted, is it not possible to reduce the number of bends by rearranging the room layout? They should also be swept bends, not elbows &, with access, will take up a lot of space; & in order to accommodate the bath waste, I assume you’re proposing to run below floor level?

Separate bath & sink connections to the stack are always the preferred option; you can boss into the top of the soil run but, either way, you will need anti-siphon provision for the traps.