I have a slow draining sink/basin in the bathroom. It has been going on for a while now and is strange as it seems there is gas/air building up behind the trap and stopping the water flow as when I open up the trap I get a his of air and a bad smell and then for a small period of time it drains fine again. I have checked for blockages and there are none and also I have checked the angle of fall of the pipe and it seems fine. Is there a way to fix this. The stack AAV is in the loft and I think this is working ok but if it was not would it affect the sink. All the other appliances in the bathroom drain fine so I don’t think it is the stack that is a problem. Advice please.

Thanks

zeroasylum

How long is the bath waste, it may also need an AAAV.

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Bath waste is very short as the stack flows down the wall at the head of the bath so really its just the trap and a small section of pipe.

Thanks

zeroasylum

Is the stack backflowing into the waste pipe in that case.

Sounds like an installation error, I would remove the AAAV in the loft and try it for a while tosee what difference it makes.

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