Air admittance valve/sluggish flush

[Ben Blaukopf]

I cut my soil pipe in the loft and capped it with a air admittance valve, the intention being to run my bathroom fan out through the roof in the remaining pipe. Now I can't swear that it was this, but my flush seems to drain away a little slowly now - as though there was a blockage in the system. the water level in the pan rises up as though it's flooding, and then returns to normal.

Is it possible that this is caused by capping the pipe with the valve, resulting in a less free flowing system?

Ben

[Set Square]

Yes - there are definite rules about where you can and can't use air admittance valves. There has to be a *proper* vent within a certain distance. If you simply replace a normal vent with an air admittance valve without following the rules you could well get the problem which you describe.

[Ben Blaukopf]

B*gg*r. Sounds like I'm going to need to remove the cap and put things back how they were, since this replaced the main vent. Haven't done any of the other work yet, I like to do things and see how they work out before proceeding, so I ought to be able to fit it all back together with some pushfit sockets.... I even have the section of pipe I cut out originally.

Ben

[Alan James]

As Set Square said there are rules, but what you are getting seems to be a blockage and can't be explained by a properly operating admittance valve. Alternatively the air admittance valve is not operating but I don't think so as your trap would be drawn if it wasn't working. Why not just take it off and try or have you cemented it in?

Alan

[IMM]

No so. Every 4th or 5th house needs an open vent, and end of lines like end of cul-de-sac, otherwise an AAV is fine.

What you have done should not slow up the draining. Take the AAV off and see if it works better. It may actually be a blockage in the drain. When it slows up it is usually a duff valve.

Try putting a HepVO trap on an adjacent washbasin or bath. These are mini AAVs in their own right.

[Set Square]

So doesn't your description amount to "rules"? You contradict what I say, and then go on to say the same thing using different words! This will only serve to confuse the poor bloke . . .but tell me something new!

[IMM]

You never said what the rules were which is very confusing. A "*proper* vent within a certain distance.", what does that mean? Another stack 2 feet away? Highly confusing.

He knows now. I even offered help on other devices too.

[Set Square]

I was simply seeking to point out that there *are* restrictions (but was unable to quote chapter and verse). That was sufficient to prompt the OP to check the rules.

To which part of my statement does your "Not so" apply?

[Richard Sterry]

A similar thing was done in my previous house. It worked fine, and so should yours. It sounds very much as if your air admittance valve is NOT admitting air - check to see if it is stuck or incorrectly fitted.

Rick

[P.R.Brady]

Would you clarify that for me please? I've a house with a private septic tank. At the house end there is an outside 4" down pipe with an open vent tucked up under the eaves - my problem is that high winds gusting over the free end creates a low pressure in the pipe (venturi effect) which sucks water out of toilet bowls - had a bone dry one once!

I've bought a valve to fix this but not yet fitted it. Before I get busy with my hacksaw, are you saying that this will not meet regulations or will not be effective?

Phil

[IMM]

The open vent of the stack is under the eves? If so continue it around the gutter and about 1 - 1.5 feet up with a bird cover on the top. You will need an open vent on your septic tank. When people are all on the same sewer, every 4th or 5th house provides the ventilation. You have to provide your own.

[Hugo Nebula]

On Thu, 13 May 2004 14:37:46 +0100, a particular chimpanzee named "Set Square" randomly hit the keyboard and produced:

But the guidance about having an open vent really only relates to any build-up of pressure within a sewer, or to vent a septic tank. It shouldn't lead to a failure to drain (see

flush will force a plug of air into the stack. Normally this would escape down the drain and up the vent, but the latter is now no longer open to it, so a slight increase in back pressure will occur. This shouldn't lead to a problem unless the drain is partially blocked further down.

[BillV]

[snip]

I think it would meet regs because you don't share drains with any other property. If your septic tank needs to vent somewhere, and I suspect it does, then you will obviously have a problem if you block the only vent. What you probably need is not a valve but a cowl - cheaper too.

[The Natural Philosopher]

An auxiliary AAV should fix this condition. It will meet regs as well. You can have as many AAV's and stack vents as you like.

[The Natural Philosopher]

Tiss bolocks. No need to carry it up higher. Mine is under the eaves comes out sideways and has a fan vent guard on teh end. BCO happy with it.

Not necessarily. I have a Klargester and that has no vent. Also approved.

First fact Eliza has got right. Randomn monkeys typing shakespeare?

That s

[IMM]

The amateur starts again. he is having negative pressure because it terminates under the eves. Get it out of the eves and around over the roof.

He has one, and it will be always certain the makes will specify he needs one. There are exceptions.

< Snip tripe by a snot >

[IMM]

If you eliminate a valve all the better as it is another mechanical part to go wrong in the future. Best to keep it naturally vented and take the stack around the gutter into the open.

[Bob Eager]

Ah. You are tellin us it should terminate under the morns...

[IMM]

????????

[hudsterou]

No he's telling us it should terminate under the adams....