Dishwasher fit - too much pipework?

MyRealNameToo

jennifernil said:

Our son and his wife were house hunting a few years back and one house they viewed had 2 dishwashers, which they could not understand. 

They asked the person showing them round, a parent  of the owners apparently, why 2 dishwashers ?   The answer was “one for the dirty dishes and one for the clean dishes.”   Perfectly logical if you have the space.

I guess if you have the space why not, I've also seen those with two washing machines and two tumble dryers which to be honest I can see more justification for given most weeks we have a whites and coloured wash to do and with two machines they could be simultaneous. 

In our office we have two dishwashers in principle for the same idea though at lunch they typically both become full and so then keeping them alternating becomes more difficult. 

WIAWSNB

greenbee said:

My DW hose was run along under the cupboards and then up to the kitchen waste and I kept having issues on hot washes with the leak detection kicking in as the water in the hose was backing up. Drilling a hole in the side of the unit so the hose goes up and over as it leaves the DW has solved this problem, so worth at least making sure it goes up and over before running it along the bottom. 

Thanks for that. Very interesting, and good to have a real life experience.
Taking the hose up to an initial high point, say through the unit side at ~800mm, would be my preferred method if using a hose extension, and then a slow fall to the sink's spigot. The hose contents from that high spot onwards will drain away to the sink waste. The small amount in the first short upright piece of hose will settle back in the machine, as it would do with the 'normal' waste setup.
I'm hoping that Joy goes for the conventional setup of the U-bend behind the machine in any case.

grumpy_codger

greenbee said:

My DW hose was run along under the cupboards and then up to the kitchen waste and I kept having issues on hot washes with the leak detection kicking in as the water in the hose was backing up. Drilling a hole in the side of the unit so the hose goes up and over as it leaves the DW has solved this problem, so worth at least making sure it goes up and over before running it along the bottom. 

How is this better than just suspending the hose higher up to the wall behind the DW before it goes down under the units? 

greenbee

grumpy_codger said:

greenbee said:

My DW hose was run along under the cupboards and then up to the kitchen waste and I kept having issues on hot washes with the leak detection kicking in as the water in the hose was backing up. Drilling a hole in the side of the unit so the hose goes up and over as it leaves the DW has solved this problem, so worth at least making sure it goes up and over before running it along the bottom. 

How is this better than just suspending the hose higher up to the wall behind the DW before it goes down under the units? 

It isn't necessarily, but it was easier to do. It is, however, better than leaving it running straight from the bottom of the DW along behind the units .

WIAWSNB

grumpy_codger said:

greenbee said:

My DW hose was run along under the cupboards and then up to the kitchen waste and I kept having issues on hot washes with the leak detection kicking in as the water in the hose was backing up. Drilling a hole in the side of the unit so the hose goes up and over as it leaves the DW has solved this problem, so worth at least making sure it goes up and over before running it along the bottom. 

How is this better than just suspending the hose higher up to the wall behind the DW before it goes down under the units? 

That would leave the main run of extended hose permanently full of water, and I'd imagine suds would settle out and coat it over time. It would also give the pump two hills to climb, but no idea if that would be an issue.

grumpy_codger

WIAWSNB said:

grumpy_codger said:

greenbee said:

My DW hose was run along under the cupboards and then up to the kitchen waste and I kept having issues on hot washes with the leak detection kicking in as the water in the hose was backing up. Drilling a hole in the side of the unit so the hose goes up and over as it leaves the DW has solved this problem, so worth at least making sure it goes up and over before running it along the bottom. 

How is this better than just suspending the hose higher up to the wall behind the DW before it goes down under the units? 

That would leave the main run of extended hose permanently full of water, and I'd imagine suds would settle out and coat it over time. It would also give the pump two hills to climb, but no idea if that would be an issue.

But what greenbee suggested was basically the same: " it goes up and over before running it along the bottom. "

Section62

WIAWSNB said:

grumpy_codger said:

greenbee said:

My DW hose was run along under the cupboards and then up to the kitchen waste and I kept having issues on hot washes with the leak detection kicking in as the water in the hose was backing up. Drilling a hole in the side of the unit so the hose goes up and over as it leaves the DW has solved this problem, so worth at least making sure it goes up and over before running it along the bottom. 

How is this better than just suspending the hose higher up to the wall behind the DW before it goes down under the units? 

That would leave the main run of extended hose permanently full of water, and I'd imagine suds would settle out and coat it over time. It would also give the pump two hills to climb, but no idea if that would be an issue.

It wouldn't be an issue - when the pipe is more or less full of water the work done by the pump only relates to the difference in head between the level of the water inside the dishwasher, and the level of the discharge point.

Or in simple terms, the water goes up a 'hill', then down a 'hill', and then back up one.  The water coming down the first 'hill' helps push the water back up the next one.  You can put as many 'hills' as you like between the pump and point of discharge, and each time the downhill will balance out the uphill. (the longer length of hose does add some resistance to flow though)

Whether the pipe run is high or low makes not much difference in terms of 'stuff' settling out of the water.  The force of the flow generated by the pump should give the pipe a reasonable clean each time.  The main problem would be with fats from the wash cycle.  The relatively clean water discharged during the 'rinse' cycles should help flush any residual material from the wash cycle out of the hose.

The main reason why having the discharge hose on the floor is better is in case the hose (or extension connector) fails.  If the hose is running through the cupboards then the cupboards and their contents possibly get soaked in dirty water.  If the hose is on the floor and fails the worst is having a wet floor.

WIAWSNB

grumpy_codger said:

WIAWSNB said:

grumpy_codger said:

greenbee said:

My DW hose was run along under the cupboards and then up to the kitchen waste and I kept having issues on hot washes with the leak detection kicking in as the water in the hose was backing up. Drilling a hole in the side of the unit so the hose goes up and over as it leaves the DW has solved this problem, so worth at least making sure it goes up and over before running it along the bottom. 

How is this better than just suspending the hose higher up to the wall behind the DW before it goes down under the units? 

That would leave the main run of extended hose permanently full of water, and I'd imagine suds would settle out and coat it over time. It would also give the pump two hills to climb, but no idea if that would be an issue.

But what greenbee suggested was basically the same: " it goes up and over before running it along the bottom. "

If the hose goes 'up' at the DW end before then running along the floor, it will leave the main hose length full of water each time - the section between the two highs. (The sink end having to be a 'high', as it needs to be above U-bend height, and also at no risk of sink waste getting into the connecting spigot - hence that spigot should ideally be pointing upwardsish, and the hose looping slightly above it.) No idea if that's an 'issue', but it doesn't seem ideal to me. 
If the hose does not go 'up' at the DW end, but only at the sink end - which it would still have to - then it would leave the content of the extended hose draining back into the DW each time. Again no idea if that's an issue, but Greenbee's machine didn't like it (rereading that post, I'm not sure why - is it added resistance to flow, or is it the hose contents flowing back to the machine when drain is finished?)
So, personally, if I had to run an extended hose, I'd try and do it via the tops of the units, starting with a 'high' hole above sink waste spigot height, and introduce a small fall all the way along. The hose would be invisible unless looked for, and I think this would be the only setup with no perceived operational issue - it would empty towards the sink waste each time. Yes, should the pipe leak, the unit and contents could get wet, but hoses generally don't leak unless a rat eats it. And, should even a small leak occur, at least you'd know. 
But still hopeful that Joy fits a conventional DW waste.

Section62

WIAWSNB said:

If the hose does not go 'up' at the DW end, but only at the sink end - which it would still have to - then it would leave the content of the extended hose draining back into the DW each time.

It wouldn't though.  If the hose is on the ground and the ends of the 'pipe' are open (i.e. no vacuum to cause siphonage) then only the water in the hose which is above the bottom of the inside of the machine could backflow - the machine is not going to suck the water back up from a hose which is lower than itself.

Furthermore, (and I might just be lucky here) every dishwasher I've taken apart for spares had a simple one-way valve in the pump assembly to prevent backflow from the drain hose.  Maybe not all manufacturers do that though.

Again no idea if that's an issue, but Greenbee's machine didn't like it (rereading that post, I'm not sure why - is it added resistance to flow, or is it the hose contents flowing back to the machine when drain is finished?)

Greenbee's issue is a puzzle.  If the leak detection is triggered by a float valve in a plastic tray underneath the machine then it should only be triggered if there is an actual leak, and a not insignificant one.  Which would mean one of the hose connections or some other part is leaking because it isn't correctly fitted.  That the issue only(?) happened on hot washes is also odd, unless it was the heat causing expansion of the leaking part allowing the rate of leakage to increase.  I can't see how conventional leak detection would be triggered by 'backing up' on a hot wash, but not on other wash types, and without there being actual leakage.

A hose being kinked, or a sensitive aquastop-type leak detector system, might possibly lead to false leak detections which could stop if the hoses are re-routed, but again, why only on hot washes?

So, personally, if I had to run an extended hose, I'd try and do it via the tops of the units, starting with a 'high' hole above sink waste spigot height, and introduce a small fall all the way along

The problem is maintaining that small fall - the drain hose isn't rigid enough not to sag (especially when hot) and allow water to accumulate in the low spots between the points of support.  If there really is some kind of issue which needs solving by running the extended drain hose at high level then the issue would only be fully solved if that small fall can be maintained along the whole length of the hose without any sagging and low spots.  Achieving that is possible, but a lot of faff to solve an issue which arguably doesn't exist.

greenbee

I have no idea why I was only getting the fault on hot washes (fault would clear if the machine was left off for a few hours) or why the problem was solved by changing the position of the hose! I didn’t buy or install the machine, but we had to take it out at one point and there was a lot of hose coiled up behind it so we decided to hook it up and over, and that meant we could make sure no hose was caught under it as we moved it back in. I still hate it (it was filthy when we moved in) and it doesn’t allow you to change the programme once selected unless you turn it off for several hours. But it’s integrated, so until we redo the kitchen (hopefully this year) I can’t replace it with the one we brought with us (currently in the garage). Mind you, the idea of having two does appeal… but getting rid of the dodgy integrated one appeals more!