We have had a bad sewer snell in the kitchen and bathroom for a couple of months now. It tends to come and go. Just some history first ... Around 17yrs ago a mate did some bathroom work, but couldn't finish it, so I got a local plumber in. He thought it would be a good idea to lop off the internal soil pipe and leave it open under the bath. I got him back to fix but it was never quite right. (Actually tried to claim he didn't do it......) The soil stack is internal and is also boxed in the corner of the kitchen, where it comes down and enters the sewer. We have the bathroom fully revamped 10yrs ago, and the plumbers fitted a proper AAV to the top of the stack under the bath. It's been fine generally until a couple of months ago, we get bad smells in the bathroom and kitchen, where the soil pipe is. I've had a plumber out, who was really good to be honest and replaced the AAV with a better quality, but noted the pipe isn't to regs, and is not as far above drains as it should be, but there's no leeway to alter it. Unfortunately the smells have returned, mainly when using the shower.... He can't get out again till later next week but wondered if anyone on here had any ideas that I could try and look at till then. I could open up the box work along the whole length to examine the soil stack directly but not sure what this would tell me. I think it smells in the kitchen as there is an entrance point in the boxing for the kitchen radiator pipes. I've tried sealing this, but it's not helping and it's not really solving the underlying issues.