I currently have a dishwasher and washing machine using the same waste water P trap, at the top of the trap I have one twin connector (see link) fitted (picture is upside down) as there is a slot at the top for air, but the problem is sometimes waste water escapes from the air hole when both appliances drain

Can I swap the above for one of these double nozzle connection (see link) (again picture is upside down) and in the other end put a blank (see link)?

or do I need an air hole?

Can't fit the wastes to the sink as it's to far away

Hope someone out there understands the above

Thanks for your help

Iainl

I,ve never seen an air hole, I have seen these where the sink overflow drops into something that might look like an air hole.

I would just block this up, traps and drains should be sealed.

You should always have the drain ventilated and to solve your problem you need and air admittance valve which let's air in and keeps smells and water inside having a vent will ensure a good water flow

The drain pipes need to be a loose fit (you need an air gap to prevent siphoning, I believe) - I think I would suggest something like simply cutting the stand pipe and put a second stand pipe branching off, therby having one for each appliance.....

.....which reminds me of an old joke......

.....why do women get married in white?

I'll leave it to the collective to provide the punchline.....


Ok, too slow - so they match the other kitchen appliances.

[Edited on 2/12/12 by stevegough]

That first link is absolute rubbish! You'd expect it to leak. Assuming it is attached to the top of a normal washing machine trap (ie a u bend with a tall pipe out of it), and you have a good foot of pipe on it (this allows it some space to back up before it overflows), i would cut it an inch above the bend, fit a 40mm compression tee (push fit wont fit), and an elbow, so you end up with two vertical pipes. Make these pipes as tall as possible, ie 2" short of the worktop, then just put one in each.

You dont always need air admittance, it does depend where the pipe is going. A waste pipe flowing into a surface gully, with a 3" water trap, will not syphon it out. However i know from experience that a 1" trap into a closed sewer does gurgle badly.