Hi, my house has 3 soils stack pipes, one for each toilet. One, for the downstairs toilet, is boxed-in so I assume it has an AAV fitted. The other 2 soil pipes vent in to the loft space. We are experiencing some smell issues and hope that AAV's will solve the problem. My questions is, can I fit AAV's to both soil stacks in the loft or does one need to vent direct to air?
Thanks
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