Advice needed on AAV

[grommett]

I have a compact ensuite shower room, it has a shower, a small basin and a toilet. When I empty the basin, it sucks the water out of the shower trap. (it doesn't happen if I just run water in the basin). The run of waste pipe starts at the Shower, the basin T's into it after about 500mm and then it continues to run for about 3 meters with 3 elbows into a vented stack pipe. The toilet has its own run to the same stack pipe and seems to have no effect on the shower. I suspect an additional AAV would help.

I would like to know if I can fit the AAV inside the vanity unit under the basin or outside between the basin and the stack. Of the 3m run of pipe between the basin and the stack, approx. half is outside which means the closest I could make it would be 1.5 - 2m from the basin.

Cheers

 

[DP]

Look at mcalpine basin traps with built in air vents.

 

[AGAS]

[URL='http://www.screwfix.com/p/mcalpine-anti-syphon-bottle-trap-white-32mm/37314'] McAlpine Anti-Syphon Bottle Trap White 32mm [/URL]

 

[Doggit]

Not sure if that will fix it. The anti syphon needs to be at the shower trap. You'd fit the anti syphon bottle trap if the toilet was sucking the water out of the basin, so the same principle needs to apply to the shower. Nees something more like an inline anti syphon for the shower.

 

[grommett]

Not sure if that will fix it. The anti syphon needs to be at the shower trap. You'd fit the anti syphon bottle trap if the toilet was sucking the water out of the basin, so the same principle needs to apply to the shower. Nees something more like an inline anti syphon for the shower.

Hi Doggit. That thought crossed my mind as well, but if this basin trap lets air in while the basin is emptying, wouldnt that prevent the siphoning effect on the shower? In any case I cant fit anything to the shower tray as it is under a tiled floor so I think I will have to try this option and keep my fingers crossed.

Thanks to all for the replys.

 

[Doggit]

An anti syphon at the basin only protects the basin trap that's upstream from it, so as the basin empties, it'll still pull the water from the shower trap, so although you can't get under the tiles, is there anywhere between the basin and the shower that you can get at. You'd need to fit an upright T piece, and then fit an antisyphon unit into the upright of the T piece. Is it possible to split the shower and the bais waste pipes.

 

[grommett]

I fitted the anti-siphon trap today and it worked. It no longer sucks water out of the upstream shower trap. Thanks for the tip.