sink waste pipe lenght problem

[john]

I am planning a new Kitchen. The problem is the waste pipe has to run in a partition wall before going under the floor between the joists to the main stack. The total run is about 8 meters in 40mm pipe. One pipe manufacturer MARLEY warn that too long a run will cause the trap to siphon or make noise. Is there any othe way round this. The pipe cannot be any bigger as it wont fit in the partition wall.

Thanks. john

[Andy Hall]

You can put a greater slope on it than specified, and also fit an anti-siphon trap or valve.

Then if the air pressure in the pipe goes negative relative to atmospheric (which would have a tendency to cause the trap to gurgle or be siphoned), air is introduced via it and not the trap.

.andy

To email, substitute .nospam with .gl

[Quddus]

just to add that wickes sell these and are called "gurglemaster" iirc.