Hi everyone. I've done a great deal of searching on this topic and only found one unanswered thread on another site from years ago that is anything like what our issue is. When we use our upstairs shower, we get a bad sulphur-y smell downstairs by the back door... The set up is as follows (forgive me if I don't use the right terminology etc, this is all a bit advanced for me): One bathroom upstairs. Loo feeds into sealed waste pipe with vent above house and pipe going into ground (sealed) right outside back door. Basin and shower are both feed out into external piping that empties in an open drain outside the back of the house, about 2 meters from the back door. Kitchen sink and washing machine feed out through completely separate external piping that empties out into the same drain. No smell from any plug holes or from the external drain, whether water is running or not. However, when we run the shower upstairs, after a few minutes a very strong eggy smell appears around the back door. It can sometimes fill the whole bottom floor and may take an hour or so to pass. When the smell is present, the drain smells fine and there's no noticeable source for the pungent odour! The shower upstairs smells absolutely fine too. We've had a plumber in who machined the pipes and said they were clear. The odour wasn't prominent when he was there, but as the boiler flue is out the back doors too, he suggested we get the boiler checked as he couldn't find any plumbing issues. Can anyone shed any light on this??
Anaerobic bacteria in your boiler. http://www.networx.com/article/boiler-is-making-strange-smell Where is Dave when you need him.
You need something like Sentinel X400 cleaner put through your heating system to throughly clean the system. Then a inhibitor like Sentinel X100 to prevent microbiological growth in the future.
Can you not run all the waste pipes into the vented 4" main pipe, or convert the open drains into sealed ones with a manifold.