Replace soil stack/stench pipe with AAV

Currently we have sodding godawful stench pipe which runs in the corner of the house (it's an "L" shaped bungalow). Next door (2 storey house) has a stench pipe running to above their eaves.
Is is possible to replace our pipe with a 120cm pipe capped with an air admittance valve ? 120 cm will put it above the overflow of all sinks in the house.
Is it as simple as remove old cast iron pipe, fix a slightly smaller pipe into exposed pipe with sealant ?
Any makes to recommend ?
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wibbled:

Well, there is one problem - and I would advise a quick shufty at the appropriate Building Regs document (Google for "Approved Document H"):
An AAV does not deal with positive air pressure (ie venting the sewer to the atmosphere. AAVs are used where local suction effects (due to flushing the bog for instance) are liable to suck u-traps dry.
I think you will need at least one vent to atmosphere, but it *may* be possible to provide one dry vent in 32mm.
Suggest looking at the document I mentioned, pages 10-14 and 23 (actual page numbers as printed, not PDF numbers).

Floplast seem OK generally.
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Tim Watts

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The rule is... Every 5th house needs a vent and every end of line. All the rest can have AAVs or HepVos.
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You cannot do it if you are the end of sewer line. Yes it is OK to do. Look at HepVO traps on all sanitary appliances,and do away with the whole stack.
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erm..... thought you couldn't *legally* use AAVs outside ? something about freezing up? mines been fine for a decade however.....:>))
JimK
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HepVO traps are not outside.
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nor do they serve WCs
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They do. They vent the whole stack. Now you know.
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wrote:

sigh.... i was clarifying that there isn't a hepvo for a bog...for sinks, baths yes but not for a 110mm bog connection...
how can the op "do away with whole stack" as you advocate - what about the bog connection? it will still need some stack to that and above for flood regs? if topped with an AAV - technically illegal outside I believe?
do you know? :>)
JimK
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JimK wrote:

Drivel doesn't know anything.
You must be new here.
Anyway the purpose of an AAV is quite different to a stack.
The stack is there to prevent positive pressure and (inflammable) gas build up in sewers.
The AAV is there to avoid vacuum when an adjacent device empties from sucking the traps dry.
Legally you need an open vent every few yards of sewer.
The general rule is one stack per house, and as many AAV's as you need.
You can get small or large ones . Or fit adaptors to them.

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On Tue, 19 Jan 2010 10:25:08 +0000, The Natural Philosopher

And don't buy them at the builder's merchants - notorious for overpricing.
I'm trying my luck with a Floplast 50mm AAV and 110-50mm adaptor for my bog. Initial mouth tests indicate the Floplast is silent (some AAVs can be quite "farty") and a good free flow in one direction. If it causes problems, I'll upgrade to a 110 AAV, but those are quite bulky, especially as I need to put in a stub pipe vertically to get it above the flood line.
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So where would you buy cheaper?...

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wibbled:

BES, MasterPlastics to name two, depending on the part.
First, I'd decide on the part (110 or 50mm), then either search by 110 AAV or narrow it down to a specific part number, say FloPlast and search for that.
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None of them appear to have branches around here (Cambridge) still it seems if you haggle a bit they'll drop the price a bit .. sometimes like some heating bits less than what you can buy online;))..

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wibbled:

Err, Tony - both of those are online suppliers ;->
OK - Masterplastics, trading as www.fascias.com do a very comprehensive range of FloPlast (including fiddly weird bits and 82mm stuff) - but don't actually seem to do the AAV.
BES:
http://www.bes.co.uk/product/130b~PL~2602~2602~-Air-Admittance-Valves.html
82 and 110, 16 quid+VAT+delivery - good if you need some other bits too - typically fast delivery.
This is the AF32 Floplast (32/40/50mm AAV) I have:
http://www.humm-busters.com/en/AF32.html
BTW - It is FloPlast who claim an external grade AAV:
http://www.floplast.co.uk/uploads/AAV%20leaflet%20black%20and%20white.pdf
And some useful reading:
http://www.floplast.co.uk/uploads/Air%20Admittance%20Valves.pdf
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Tim Watts

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wibbled:

Yep:
Benefits
The Building Regulations, Document H1 sub section 1.31, stipulates that any soil and vent pipe installed externally within three metres of any opening window, is required to terminate a minimum of 900mm above the window. This new development to the traditional internal Air Admittance Valve allows a soil stack fitted with an external Air Admittance Valve to terminate within three metres of a window opening. This allows the pipe to terminate at the same height as if it were installed internally i.e. 200mm minimum above the highest wet entry point to the soil vent pipe. (diagrams a & b). The use of an external Air Admittance Valve eliminates the need for the installer to work and handle pipe above the roof line, making it easier to comply with Work at Height (WAHR) and Manual Handling Regulations.
The Floplast external AAV can terminate below a window if window is 3metres away. This precludes most UK homes. If the stack is nearer than 3 meters to a window then it has to terminate 900mm above the window - may as well dispense of the external AAV then.
Look at HepVos

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On Tue, 19 Jan 2010 15:14:38 +0000, "Doctor Drivel"

Although these are useful if they get you out of a sticky situation, personally I think they're a crap idea if you have the option of an open vent as is most usually the case with an external stack (OP's complain excepted).
An open vent with a bird-grill on top has almost nothing that can go wrong with it.
Also, the bit about working above the roofline is bollocks. Generally, IME, the last clip supporting the pipe is below the roofline. Adding the bit above the roofline is generally no more difficult than pre assembling a bit of pipe (about a metre or so) with 2 45 degree couplers (preferably solvent weld for rigidity) to offset round any guttering and a bird mesh on the top. Up the ladder, this is fixed (solvent weld again best) to the top of the stack. Even easier would be to make up a 2m section including the offset and plug it in a push fit coupler, securing the new part with a couple of clips to the wall.
I can see these things being in demand so that internal stacks don't need to perforate the roof (vent from the loft) but even there, I think there's going to be less long term grief taking them outside. AAVs are going to fail sooner or later so they introduce a maintenance issue. Certainly had no trouble with the first approach with mine.
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You are right about getting around the gutters. It is easy to do and you don't need to get on the roof.
I believe they will allow 80mm above the point where no water will enter the stack, for venting. I once saw a 110mm stack enter the loft then go to 80mm. It went across the joists and out via the eves, doing down and up around the gutter using elbows and a bird cage on top. The roof tiles were not penetrated. It is only venting. I am not sure if it legal. It had a tee with a short piece and access plug, rather than an elbow, on the external vertical section. I assumed this was to remove any debris than may have fallen down the vent and collected at the bottom of the loop. It must have saved a ton of time and expense rather than take up a roof tile which needs staging access. All he had was a footed ladder.
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On Tue, 19 Jan 2010 18:35:32 +0000, "Doctor Drivel"

It was one bit of the building regs I did read in some detail.

Yes - technically 75mm - but that has obviously been chosen so that any variant on 80/82mm pipe will do even if those are outside diameters and the regs call for inside diameters...

Bizarre but functional. The worst it will do is get some water in the lowest bit, but that will clear if its services are required.

Mine isn't even directly from a wet stack (those all appear under various parts of the floor). Mine is a separate vent pipe directly teed off the furthest leg of the underground drains close to where a loo couples in close to the 1st inspection chamber (convenient - needed to retro fit the vent, found a tee in the pipe for a gulley drain - removed gulley and connected vent with a 82mm adaptor underground).
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Tim Watts

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Thats why I can't find them then;)..

Well a lot of the time when I need stuff like that I need it now and more often than not will go and get it from a decent local BM here who's prices when you haggle a bit will come close to or very near those online. Plus there are some very product knowledgeable people there too..
Plus you haven't got to hang around waiting for delivery wagons to turn up...and than if you need to exchange something as its not quite the right bit or you can take that bit with you and compare it with wheat they have etc...or if it goes wrong then you've got to bag it up to return etc.
Which is the biggest bug bear of buying online and they never seem to get that any more user friendly..
Same with a lot of other stuff like computer bits we have World of Computers here who's prices are around those online and by the time you've factored in delivery costs etc..
Course not everyone might be so well served;!....
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