Going round the bend...

It would just act like a giant trap surely? Can't see why it would't work.

Would need to ensure there was easy access as it would block easily though.

Darren

A blocked trap full of 10 gallons of tea leaves and grease? *I* don't want to empty it!

Andy

It would work. Until the sump accumulates enough grot to block it.

In a normal U-type waste the entire content is flushed almost whenever you use it (as it retains so little water). In the version you describe there could be a lot of water which might well not flush through for long periods. That is a recipe for blockage and truly revolting stagnant waste.

Any possibility of fitting the units 50mm in front of the wall so that there is a gap behind the oven? Or taking the waste out through the wall?

That would work, it's just a giant trap. Any new incoming water raises the level and displaces water 'over the edge' into the downstream pipework. Like a WC bowl - they can cope with rushing water.

On the other hand, it would be highly vulnerable to blockages, any grit or fibre which settled in that section would stay there, gradually gumming together with hair, fat & fishbones. Ask the old boy to promise that he'll dismantle it and flush it with caustic soda once a month, and it might be viable.

I've used that sort of arrangement for condensate wastes but I'd expect using it for dirty water would result in it blocking up with large amounts of muck settling out in it.

Offer to fit a Saniflo.

See if their god really is on their side.

More sensibly, tell them the big u bend wouldn't comply with building regs (I'm pretty sure it wouldn't comply with the rules on falls on pipes).

It sort of would. BUT the mass of water would take some acceleration to get moving, and probably carry on, possibly sucking it dry.

I am not sure its to regulations either.

Easy answer.

Fit MDF false wall and tile it.

As per all the other answers, it would work, as long as it's sealed. And it would block easily in that situation too.

Here's somewhere else it was used, on a somewhat larger scale:

A U-bend is a U-bend. All you have here is a ginormous U-bend.

That is not to say that a ginormous U-bend is going to be in the slightest bit desirable.

-- JJ

I can just picture one of the old dears getting sucked down the plughole after emptying the teapot. She would probably get stuck, so you'd need a waste disposal unit to finish the job.

-- JJ

In message , The Medway Handyman writes

Can you not move the whole lot 40mm clear of the wall and fit something along the work top to take up the space? Alternatively shunt the oven/hob unit forward?

regards

Others have come up with varying comments about the arrangement. I had a problem in my last house with what turned out to be a long unsupported length of waste under the floor boards in an upstairs kitchen. It drained washing machine and dishwasher, and becaue it had been installed without any clips for a length of about 6-8 ft. It had been installed with a fall, but eventually sagged just an inch or two, and the dip finally clogged up with crud, which manifested itself when the w/m pumped out through the d/w! New floor, new ceiling downstairs, plumbing corrected......[1]

Yes, tell then it can be done, instal with a couple of access points for cleaning out, but strictly at their risk, and on the understanding that they will be responsible for cleaning out the pipes. If they want you to do it, tell them it will be a very unpleasant job, and your charges will reflect that.

ROFL! (having just had to open mine up to wiggle the spade connectors on the timer)

It will work, but there is a fair risk of syphonage. I would keep the low level section as short as possible and step up to 50mm pipe immediately after the last elbow before the soil pipe. If possible, I would also fit a running trap at the start of the lowest section, which ought to attract much of the rubbish as well as making cleaning it out easier, and I would fit access points at every elbow. There also ought to be a running trap in the50mm pipe, just before the soil pipe, just in case the rest does manage to syphon out.

Colin Bignell

Hadn't got that far, but you are right, its asking for a blockage.

Yerbut, nobut, yerbut if you pulled out the plug on a sink full of water, it would have the effect of compressing the air in the waste upstream of the U, so less water would be pushed out of the other end?

Alas no, the kitchen is narrow anyway & there are several door frames on the other side of the wall.

What an un Christian idea :-)

Aha! My Get out of Jail Card!

Cheers