Water coming out of AAV on anti-syphon bottle trap - ideas?!

[OllieX2]

Hi all.

I have an anti-syphon bottle trap made by Center Brand Traps under my kitchen sink. It's similar to this one by McAlpine.

I noticed that a few drops of water would leak out of the air admittance valve when I drained a full sink of water, so I unscrewed the unit, gave it a clean (I found that half of the bottle was blocked) and re-assembled.

Now, when I drain a full sink of water, water pours out through the AAV

Do you have any ideas what might be causing this? I've checked that the pipework is clear from between the sink and up to about 2 feet beyond the bottle trap. There are no problems with drainage - the sink has always emptied rapidly. Couple of things I'm thinking:

1) Is the volume/pressure of water being drained from the sink too much for this type of trap, or is the distance between the trap and the sink too great? I didn't think this was an issue for these kind of traps, but it's as if water is coming up from the bottom of the bottle trap at such pressure that it's getting fired straight up into the AAV and forcing its way out of the valve rather than just flowing through the drain pipe? Could anything further downstream be causing the problem?

2) Could there be a problem with the AAV? i.e. would a replacement unit fix this? There's a photo of the valve piece below - it just sits over a hole so doesn't seem like it will do a very good job of providing a seal. Is there a piece (e.g. a spring?) missing? I inherited the plumbing setup with the house. When I unscrewed the AAV, I found a small piece of scrap plastic sitting on top of the valve piece (maybe to weigh it down?) and it looks as though silicone sealant had been applied to the outside of the valve in the past (maybe to seal it closed?)

Thanks for any ideas!

Untitled

• OllieX2
• 15 Nov 2013
• 1

Untitled

• OllieX2
• 15 Nov 2013
• 1

 

[Charnwood]

http://www.mcalpineplumbing.com/anti-syphon-traps

Theoretically, water entering the air inlet valve (AIV) should be prevented from escaping by the black washer.
Once the water has drained out of the AIV the suction pressure is supposed to open the AIV, allowing air to follow the waste water, thereby preventing gurgling and trap water being vacuumed away.

Fluidmaster/Opella do anti-vac traps that are not 'open-to-air', therefore no chance of leakage.

http://www.fluidmasteruk.com/our-pr...-bottle-traps-all-76mm-seal-all-anti-vac.html

 

[Galoka]

McAlpine also do them - their resealing traps as opposed to the ones with the AAV, more likely to get a bit of noise though.

If I was replacing a kitchen bottle trap I'd consider replumbing with a P trap. We have a bottle trap on our sink and it's more prone to blocking with bits of crud that get down the plug hole as stuff gets stuck at the bottom rather than being washed through

 

[OllieX2]

Thanks for the replies.

Do you think a new one will have the same issues due to the size of the sink (it's only a standard kitchen sink though) and the position of the trap and pipework?

Or should a bottle trap with AAV be fine in this situation, and it's more likely that my one just has a rubbish valve?

For the time being I've sealed the valve with Plumber's Mait (which I guess has turned it into a resealing trap) which has stopped the leakage but made it more noisy as expected.

 

[Galoka]

Well, it shouldn't do it, so I guess the AAV has become faulty. I'd just replace the trap