AAV quickie

[Pocster]

Just checking !

 

1) Has to higher than highest cistern ?

 

2) 110mm AAV pipe - preferable ?

3) Can tee off the main drain anywhere ? Doesn’t have to be at the end of cisterns ? Just anywhere ?

 

4) Must run vertical into loft - can then can go horizontal; must end vertical though ?

 

I’m 99% that’s all ok ... but post just in case ...

[Gone West]

23 minutes ago, pocster said:

Just checking !

 

1) Has to higher than highest cistern ?

 

2) 110mm AAV pipe - preferable ?

3) Can tee off the main drain anywhere ? Doesn’t have to be at the end of cisterns ? Just anywhere ?

 

4) Must run vertical into loft - can then can go horizontal; must end vertical though ?

 

I’m 99% that’s all ok ... but post just in case ...

 

1. Should be higher than highest waste although some makes work below that level.

2. I have one 110mm AAV and two 50mm AAVs.

3. Can do, I've got mine at ends on pipe runs.

4. Doesn't need to go as high as loft. I have mine behind false walls in with concealed cisterns.

 

[Pocster]

12 minutes ago, PeterStarck said:

 

1. Should be higher than highest waste although some makes work below that level.

2. I have one 110mm AAV and two 50mm AAVs.

3. Can do, I've got mine at ends on pipe runs.

4. Doesn't need to go as high as loft. I have mine behind false walls in with concealed cisterns.

 

I’m going to the loft and running it horizontal just to get it near the loft access hatch . Don’t fancy crawling through tight spaces if there’s an issue ?

Why do you have multiple AAV’s ? I was just planning on installing one . Thinking now - that HAS to be at the end of the soil run , yes ? I.e past all other connections 

Edited March 3, 2020 by pocster

[joe90]

Yes, (and running uphill slightly towards it if it were me.) I only have one ?

Edited March 3, 2020 by joe90

[Pocster]

2 minutes ago, joe90 said:

Yes, (and running uphill slightly towards it if it were me.) I only have one ?

Ok ! Well my soil pipe ceiling suspended will naturally have a fall to outside . So at the other end I.e ‘uphill’ I’ll install it . Pita because I didn’t allow for a vertical 110mm pipe in the stud ?

[Gone West]

6 minutes ago, pocster said:

Why do you have multiple AAV’s

I have a 110mm AAV on top of the main waste pipe in the centre of the pipe runs and a 50mm AAV at each end of the 50mm pipe runs which join each side of the main pipe. One for the bath end and one for the ensuite shower end. It's just a bit of redundancy in case there is a problem.

[joe90]

37 minutes ago, pocster said:

because I didn’t allow for a vertical 110mm pipe in the stud ?

I didn’t go vertical with 110  pipe to AAV, just 50mm Is sufficient ?

[Temp]

1 hour ago, pocster said:

Thinking now - that HAS to be at the end of the soil run , yes ? I.e past all other connections 

 

If this AAV is going on the end of a branch off a stack then yes it's best at the end of that branch.

 

If it's going at the top of a stack my understanding is that BCO like the stack furthest from the main sewer in the road to be open vented. Any other stacks can have AAV. However I believe current regs only require one open vented stack for every 5 houses (or something like that) so you might be able to argue the toss with the BCO.

Edited March 3, 2020 by Temp

[Pocster]

39 minutes ago, Temp said:

 

If this AAV is going on the end of a branch off a stack then yes it's best at the end of that branch.

 

If it's going at the top of a stack my understanding is that BCO like the stack furthest from the main sewer in the road to be open vented. Any other stacks can have AAV. However I believe current regs only require one open vented stack for every 5 houses (or something like that) so you might be able to argue the toss with the BCO.

Yes it's end of the stack. The main drain is shared with just one other property that does have a stench pipe. I'm not going to have a stench pipe - worst case I'll add an external one later.

Does the pipe coming off my 110m smile HAVE to be 110mm to the AAV?? - PITA!

Edited March 3, 2020 by pocster

[Pocster]

1 hour ago, joe90 said:

I didn’t go vertical with 110  pipe to AAV, just 50mm Is sufficient ?

You sure that's ok? - regs wise I mean?. I can't find regs about the pipe size to the AAV

Edited March 3, 2020 by pocster

[joe90]

2 hours ago, pocster said:

You sure that's ok? - regs wise I mean?. I can't find regs about the pipe size to the AAV

yes. I asked on this forum. Not sure who advised me, may have been the welsh wizard but it was a long time ago,!, if I remember correctly it was said that even a toilet flushing will not completely fill a 110mm diameter pipe so a 110mm AAV is not required. In the time since my build was finished I have had no problem with “suction” even without anti vac traps.

[MJNewton]

2 hours ago, joe90 said:

 if I remember correctly it was said that even a toilet flushing will not completely fill a 110mm diameter pipe

 

It definitely will. I temporarily capped off our soil pipe at the top and whenever the toilet was flushed with toilet paper the waterless traps would all 'rasp' due to the  suction. Sounded terrible. Refitting the AAV cured it.

 

That's not to say a small(er) AAV won't suffice though.

Edited March 3, 2020 by MJNewton

[Temp]

Stacks don't have to be 110mm....

 

The approved document has a table that specifies the Stack Diameter required for different Flow rates. The minimum size in the table is 50mm as I recall. The top ventilated part has even less flow (none!) so presumably can be 50mm.

 

[andy]

Finally we've escaped the rain and mud and have a semblence of a house...

 

I am having a "discussion" with BCO about AAV.  They are insisting that I have to have a penetration through the zinc roof for the furthest connection from the mains sewer and an AAV is not acceptable unless my structural engineer (eh?) can mitigate the yellow hightlighted:

 

1.33 Ventilated discharge stacks may be terminated inside a building when fitted with air admittance valves complying with BS EN 12380:2002. Where these valves are used they should not adversely affect the amount of ventilation necessary for the below' ground system which is normally provided by open stacks of the sanitary pipework. Air admittance valves should be located in areas which have adequate ventilation, should be accessible for maintenance and should be removable to give access for clearance of blockages. Air admittance valves should not be used outside buildings or in dust laden atmospheres. Where there is no open ventilation on a drainage system or through connected drains, alternative arrangements to relieve positive pressures should be considered.

 

Any thoughts...?  I'd rather have an AAV no no daft cold bridge/cowl on my zinc roof but not sure how to convince them...  foul water is like this with the only air admitance we're talking abotu needing being bottom left corner - no redesigning the foul runs now please or I'll cry

 

[Gone West]

@andy We aren't connected to a main sewer but the BCO was happy for us to have AAVs inside the house, so no penetrations through the roof, and to have a separate external vent on the below ground pipework. The external vent was only around 600mm high with a mushroom top.

Edited March 25, 2020 by PeterStarck

[andy]

I just need a way to calculate the "amount of ventilation" somehow - anyone have any ideas?

 

I am happy to have a couple of AAV - one bottom left, one in attic just below the "B" in the image above but need to justify with some numbers.

[Mike]

5 hours ago, andy said:

I just need a way to calculate the "amount of ventilation" somehow - anyone have any ideas?

Their use of 'amount of ventilation' doesn't relate to a specific volume, IMHO. The regs require a vent pipe at or near the end of the drain run to allow potentially explosive gasses to be vented out of the sewer. An AAV does the opposite, allowing air to flow in if there is a negative pressure, to preserve the seal in waste traps.

 

As Peter suggests, a separate external open-vented stack is the likely solution. That could run up the outside of the house, but a short stack in a nearby hedge would probably be ideal.

[joe90]

I have an AAV within the house but an external vent stack on my garage (furthest toilet) on your diagram can you not put a stack on the bottom left external drain which is the furthest point and no cold bridge.

[andy]

On 25/03/2020 at 16:53, joe90 said:

I have an AAV within the house but an external vent stack on my garage (furthest toilet) on your diagram can you not put a stack on the bottom left external drain which is the furthest point and no cold bridge.

Hi

 

I could do but the path down the side is quite narrow so would be a bit in the way.

 

Options I have as I see it:

 

1. Somehow get agreement I can have 1 or 2 AAV internally
2. Put an external vent on the bottom left either going straight up through the roof or dogleg out through the gable wall at the bottom of the picture - we have a decent overhang of the verge there, so it can either terminate under the verge (no opening windows anywhere nearby) or even go through verge and zinc roof there if I had to.

It would be great if I can quantify the vent requirement to prove 2 AAV will suffice I guess

[JFDIY]

I'd check the regs, if it's just a vent I think you can use smaller pipe, it doesn't have to be 110mm.

 

And could you bring it up in the house but then turn 90 through an end wall to avoid going through the roof, again need to check the regs as I think it can't terminate under an eaves for example.

[andy]

I have been told we can go down to 75mm instead of 110mm (not sure if 75mm exists as a valid pipe size tbh!) and think under the eaves is OK, which at least stops me needing to go through the zinc which might be the easiest fall-back if I really can't do AAV...  I hate the inconsistency of building control!

[joe90]

My internal AAV Is 50mm !,!

[andy]

2 minutes ago, joe90 said:

My internal AAV Is 50mm !,!

See what I mean...

[joe90]

As I posted before I have an external 110mm stack to vent the external pipework from my treatment plant but wanted an internal aav to stop traps possibly gurgling (a pet hate) and it works very well.

[Temp]

As 

5 hours ago, andy said:

I have been told we can go down to 75mm instead of 110mm (not sure if 75mm exists as a valid pipe size tbh!) and think under the eaves is OK, which at least stops me needing to go through the zinc which might be the easiest fall-back if I really can't do AAV...  I hate the inconsistency of building control!

 

Just for info..

 

Part H..

 

1.32 Sizes of stack ventilation pipes – stack ventilation pipes (the dry part above the highest branch) may be reduced in size in one and two storey houses, but should be not less than 75mm.