Drainage Smells in Bathroom

13 Mar 2012
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United Kingdom
We have a bungalow and recently have had intermittent drainage smells in our bathroom and adjoining airing cupboard, the bathroom was refurbished 2 years ago so I am assuming the pipe work is OK. :confused:

The soil pipe or stack in the loft has an AAV fitted when built 12 years ago, if this has malfunctioned could this be a possible cause of the bad smells? :?:

Many thanks in advance Roy :)
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If AAV is stuck open then it'll allow the drain to vent into the loftspace. Otherwise check you havent got a trap being 'pulled', or a dodgy joint somewhere allowing foul air in.
Thanks for the quick reply Hugh. Could the AAV be stuck closed:?: if so could that be the cause of the smells :?: Pardon my ignorance how do I check if a trap is being pulled :?:

Thanks again Roy ;)
If the AAV is stuck closed then that wont allow foul air to escape at that point, but could be cause of traps being pulled (siphoning). Do you hear any gurgling noises when other appliances are being discharged?
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An AAV is not a substitute for an open vent. It is specifically designed NOT to release trapped air and sewer gases.

You should have an open vent stack at the head of your drain run to relieve both positive and negative pressures. AAVs should only be fitted on secondary stacks where traps may get drawn, as they only relieve negative pressures.

Without an open vent somewhere, positive pressure can build up in the drains and force gases back through traps.
Many thanks to you all for your help, fingers crossed I think the problem has gone away as there has not been any smells since I tinkered with the AAV in the loft.

I think it must be as you said a siphoning problem and I may have unstuck the AAV by messing with it. :confused:

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