Waft from washing machine?

[veneeroftheweek]

We've got a horrible sulphurous smell that wafts into our kitchen, possibly from the washing machine. It seems to happen when the toilet, which is directly above the kitchen and presumably connected in some way, pipe-wise, is flushed after it hasn't been used for a while. I'm determined to get to the bottom of this but not sure where to start. I checked the back of the washer and it doesn't seem to have a proper trap (see picture and please excuse the filth). If I get something more "u" shaped, is that likely to help trap the smells? Or does anyone have any other suggestions?

I know plumbing issues don't make the best bank holiday reading, but if anyone's got any suggestions...

From the picture it certainly doesn't seem like there is any soft of water seal, possibly could be something on the further down the line. Also depends if this connects directly to the soils stack or empties into a gully. It may be worth buying a trap/u bend and seeing if that does the trick as a cheap first shot. Ideally you should try to get about 80mm of water seal (online building regs/general googling will tell you the minimum seal depth that you should have).

the vertical pipe (stand-pipe) should have a trap at the bottom. They are usually sold with a U-bend for appliance wastes, as a kit. It costs very little. Measure the existing pipe size carefully.

www.screwfix.com/p/mcalpine-standpipe-appliance-trap-40mm-white/94360?_requestid=239060

Done properly, it is better than attaching the appliance hose to a sink waste.

btw it looks like somebody has tried to seal the top of the pipe. This is wrong, the waste hose should be a loose fit in the pipe with an air gap to prevent pressure or suction. It is the (missing) trap that should provide the seal.

Thanks for this. I will give it a try.