Hi all Our externally vented ‘traditional’ stack vent (through the roof) kept leaking through the roof with rain water so to solve the issue for good we cut off the stack pipe in the loft and fitted an air admittance valve and got a roofer to patch the roof in late April. All was fine until about 2 weeks ago when a horrible smell was coming through en suite shower plug hole. I’ve tried everything, drain cleaners etc but to no avail. Husband checked manhole and all clear so no blockages. I emailed flo plast who said AAVs are factory tested so doubtful it’s faulty especially as only a few months old. Anyway last night husband got in loft and took AAV off altogether and the smell has now gone from our plug hole. (Loft stinks though and may be a health hazard right now?!) So I have lots of questions! Is it worth trying a new AAV or is it just that an AAV isn’t quite right for our system? Whenever we flushed main loo the AAV made a racket and released pressure from AAV. Maybe this was pulling water out of traps?? But not sure how this could be solved (can toilet pressure be adjusted?). We are thinking we should extend soil pipe back through roof and have an air vented system again. Would you agree? What would be the best way to vent back through the roof and is it a plumbers job or a roofers? I’ve attached a photo so you can see the loft set up. Sorry for all the questions. I thought an AAV was the answer to all our problems but nothing but trouble! I’m now regretting cutting the stack pipe off in the loft in the first place!