cap off waste

[WilliamInLondon]

Hello All

My washing machine drains into a 40mm standpipe with ubend which connects with the sink waste after its trap. Hence blocked sink can lead to overflow of the standpipe and flood. Ive done the snake and cleaning but its become more of a problem with new tenants.

So Id like to effectively cap off the standpipe. Then a blockage would just result in the machine waste filling up the sink.

So if I replace the standpipe with a sink unit with the top capped off that would do it.

However I cannot find a cap fitting which fits to top of the new trap ( where you would connect the sink waste normally ).

A 32mm compression cap just about screws onto the first couple of threads but would need silicone to be watertight.

Looking for thoughts on the best way to do this?

Very many thanks in advance

 

[ShaunCorbs]

Problem is the trap needs to vent else it would create a suction and the water wouldn’t go down so needs an air gap

Can’t you adjust the sink trap to incorporate a washing / appliance waste connection ?

 

[WilliamInLondon]

Problem is the trap needs to vent else it would create a suction and the water wouldn’t go down so needs an air gap

Can’t you adjust the sink trap to incorporate a washing / appliance waste connection ?

Ah ok that makes sense - as it connects to the sink waste only after its trap. In that case the washing machine drain hose would need to be extended by four feet or so to the sink and join a new waste there in the normal way. I'll measure up and look into that!

Many thanks!

 

[WilliamInLondon]

Hi

One more thing comes to mind before extending the washing mahine drain to the sink waste. The boiler sits about 12 in above the level of the top of the sink with the vertical condensate pipe teed into the 4-mm waste with stand pipe/trap which curently accepts washing machine waste and I am now going to cap off - so no longer any air break.

As the boiler is quite high above the level of the sink - normal sink blockages cannot backflood the boiler. But if the sink was vigorously plunged water could be forced back up the condensate pipe. Is this a concern? ( one way valve )?

Thanks