"lardconcepts" wrote in message
...
Long story cut short - very old building, second hand kitchen, new
dishwasher.
Without going into details, there are two good reasons for not being
able to run the recommended 32mm standpipe behind the cupboards and
through the 2'6" thick outer stone wall, in which a 23mm hole could
easily be made, but a 32mm one would be "a nightmare" (plus I'd have
to hack holes out of the back of the kitchen units.

One builder and one plumber can't see any way round it other than to
just have a 23mm wastepipe.

As long as there was a good fall (there would be - 600mm over 6 feet -
mixing my measurements here!) and the top of the pipe was the 800mm
the manual specified, can anyone see anything wrong with it?

The entire pipe run will be sealed, so no trap needed inside.

I guess what I'm trying to get at is - it's not ideal, but in the case
of their really being no other option, is there any reason it won't
work? And I've already thought about build up, but as the wash is
about 90 degress and full of evil chemicals anyway, I can't see it
getting the kind of fatty deposit buildup associated with cooler sink
water and normal "hand strength" detergent.

Just to pre-empt questions about building and water regs, they're not
going to actually fit it themselves, it was left as "regulations, see,
but if you thought about it, you could...", and the outflow WILL be
teed into the sink waste, just outside instead.

Been there seen that with a dishwasher outlet plumbed in 22mm copper as
being the only way to get the waste behind a kitchen unit and through a
limestone thick wall.

Apparently worked fine for couple of years (2-3 ?) then dishwaser had issues
emptying. Fault finding guide said "blocked drain/outlet pipe" which it was.
Removing the fitted dishwasher and using drain unblocker got it going again
but blocked again in a month or two. Also had issues connecting the drain
hose to 22mm pipe in a leak free manor. It always had a slight leak.

The 22mm pipe was changed to a longer washing machine type hose (5 meters ?)
and that was better but eventually leaked at a tight bend after about 5
years.

The whole lot was then redone correctly in 32mm plastic pipe, which involved
removing kitchen units from under the work top, chiseling the wall to get a
32mm trap in and drilling a 32mm hole.to outside.Worked fine for years no
issue until dishwasher died !!!.

I have personally changed a dishwasher hose from the supplied 1.5m hose to a
longer hose 3m (involves getting inside the dishwasher to attach the hose)
so the outlet hose could pass behind a kicthen unit to the drain spigot on
the kitchen sink U bend. Still working as far as I know.