Smelly bathroom

[tryitandsee]

Is it possible to extend the external (horizontal) waste pipe leading to the stack, to the left, incorporating a bend with short length of vertical, either leaving it open ended or finding an anti syphon type fitting on the end.

Or do the same on the small shower outlet (external) with a small vertical pipe where it bends into the wall.

Both ways the air will be allowed to get in, stopping the siphonage affect.

Mean while I would suggest you take off the rodding acess (far left) and push the hose pipe down all the way to the stack. You'll be amazed at what gunk will be lying in that long length of waste pipe.

 

[Richard C]

Is it possible to extend the external (horizontal) waste pipe leading to the stack, to the left, incorporating a bend with short length of vertical, either leaving it open ended or finding an anti syphon type fitting on the end.

Or do the same on the small shower outlet (external) with a small vertical pipe where it bends into the wall.

Fitting an air admittance valve on the last (furthest from the stack) vertical pipe in the branch would have the same effect; leaving it open won't comply with BR's if there are windows or air vents within the controlled zone.

 

[crt]

Oddly enough I took the caps off two of the vertical feeds (the one furthest from the soil stack (bath) and the closest one (shower) yesterday afternoon to see what would happenn and we don't have a smell anymore. Question is: do I leave them open (breach building regs) or put an air admittance valve on them (one of them), and if so, should the pipe be extended up to beyond the sink overflow level to avoid flood risk?

 

[tryitandsee]

I would extend the bath one slightly (in my opinion aesthetics are just as important here, put in what looks OK) and with due respect to RC, don't worry about BR's. As for flooding, it's external, does it matter.

If it sorts out a problem without disturbing all the internal pipework, I know which way I would go! Good luck.

 

[Richard C]

Oddly enough I took the caps off two of the vertical feeds (the one furthest from the soil stack (bath) and the closest one (shower) yesterday afternoon to see what would happenn and we don't have a smell anymore. Question is: do I leave them open (breach building regs) or put an air admittance valve on them (one of them), and if so, should the pipe be extended up to beyond the sink overflow level to avoid flood risk?

I’d extend the (bath) pipe at the end above sink overflow as you say & stick an air admittance valve on the top. You might as well do what you can with it to cure the problem & comply with the BR’s as far as is possible; an extra couple of feet of pipe & a ten quid air admittance valve is hardly going to break the bank! If you leave the pipe open as suggested, not only will you merely transfer the smell outside you’ll get swarms of flies around there in summer & do you really want the risk of water flooding down the outside wall! I would still check out the top of that stack & if there is no valve, fit one; 110mm Durgo’s are a little more expensive - around 15 quid!

 

[crt]

For anyone interested, it turned out that the problem here was a very blocked trap - 10 years of lady stuff down it. To recap, the smell was coming from the shower trap that shared a common waste pipe with two basins and a bath, all feeding to the main soil pipe. After much detective work it emerged that the foul smells only came from the shower after one sink (the lady one) was used. Cleaned the trap (a tall tight, "s" trap) and it's now fine.

 

[fatplumber]

Air admittance valves Should not be fitted outside. Soil-vent stacks are there for a reason and must extend above roof line to allow effective ventilation of the sewer.

 

[Richard C]

Air admittance valves Should not be fitted outside. Soil-vent stacks are there for a reason and must extend above roof line to allow effective ventilation of the sewer.

You are correct; a foul drain must have both positive & negative ventilation, hence the need for at least one open vent on the system.

You can in fact get externally rated AAAV's
http://www.humm-busters.com/en/MVdescrp.html