I have recently plumbed in a new bathroom suite conecting the wastes of the sink, walk in shower and bath to the same pipe. Now when we pull the plug on the bath or sink water comes back up into the shower giving off a whiff if it hasn't been used for a couple of days. Have I done something wrong...
Smelly?
- Thread starter moose
- Start date
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Yes!
Combined wastes:
You are "supposed" to take each waste line back to the stack individually, which avoids your problems. But in the real world you don't always have that option.
There are 3 problems - you may have more than one.
1) The water comes back up the "wrong" pipe before it gets to the stack and out. This you alleviate by connecting as near to the stack as you can, and have good gradients (drops are good) on your pipes, If you have to, fit a non return valve, though that could give you a maintenace problem - they block with hair from showers.
2) the plug of water from say the basin pushes air in front of it. The STACK is vented so it wouldn't matter if it went there, but in long runs it can push back up through water traps on other fittings, and you smell it. No real fix for that one, but using big pipes helps a lot. Plugs of water are less likely, and there's a lot more air to squash so the pressure increase is less. You should have used 2", say.
3) the plug of water can suck the water out of a trap on any waste connected, as it passed the tee point. That one is easy to fix - put (an) air admittance valve(s) in the system. These can be pipe fittings or incorporated into traps. The basin trap is a convenient place to have one usually.
There are traps with air admittance valves and "anti syphon" traps, which are made so that air can pass without emptying the water from the trap to the point where it no longer "seals". They make a lot of noise and let air UP the pipe more easily - I'd advise the AA type. (they have a small cylindrical addition on the exit pipe)
Combined wastes:
You are "supposed" to take each waste line back to the stack individually, which avoids your problems. But in the real world you don't always have that option.
There are 3 problems - you may have more than one.
1) The water comes back up the "wrong" pipe before it gets to the stack and out. This you alleviate by connecting as near to the stack as you can, and have good gradients (drops are good) on your pipes, If you have to, fit a non return valve, though that could give you a maintenace problem - they block with hair from showers.
2) the plug of water from say the basin pushes air in front of it. The STACK is vented so it wouldn't matter if it went there, but in long runs it can push back up through water traps on other fittings, and you smell it. No real fix for that one, but using big pipes helps a lot. Plugs of water are less likely, and there's a lot more air to squash so the pressure increase is less. You should have used 2", say.
3) the plug of water can suck the water out of a trap on any waste connected, as it passed the tee point. That one is easy to fix - put (an) air admittance valve(s) in the system. These can be pipe fittings or incorporated into traps. The basin trap is a convenient place to have one usually.
There are traps with air admittance valves and "anti syphon" traps, which are made so that air can pass without emptying the water from the trap to the point where it no longer "seals". They make a lot of noise and let air UP the pipe more easily - I'd advise the AA type. (they have a small cylindrical addition on the exit pipe)
Sounds like you need to look at your traps and waste pipe.
Check for blockages by unscrewing and also check how you have routed your wastes as it could be that you are sharing wastes incorrectly.
You may need air admittance valves or anti vac traps.
A drawing would be helpful
Check for blockages by unscrewing and also check how you have routed your wastes as it could be that you are sharing wastes incorrectly.
You may need air admittance valves or anti vac traps.
A drawing would be helpful
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