Help with plumbing in Dishwasher

[joshreade]

Hi

I have just bought my first dishwasher and I am having some trouble with plumbing it in.

The only under counter space for an appliance is the other side of the kitchen, about 3 meters away from the plumbing.

There is however a cupboard the other side of the wall directly behind the dishwasher.

From what I can see I have two options... Run the hoses through the wall and share the plumbing with the washing machine, I think this would involve using a 'T' splitter where the current water intake for the washing machine is, and a 'Y' merger connecting to connect to the waste, sharing with the washing machine.

Or... purchase some hose extensions and run the hoses behind the worktop cupboards to the sink, where there is a vacant intake and waste fitting. The extension would have to be 2.5meters minimum.

I have looked at forum posts for both scenarios, and there seems to be drawbacks for both. Namely; with option 1 the pressure of the water might not be enough to run both appliances at once, and the waste pipe may not be able to handle the extra output. With option 2, people are suggesting that problems may arise from using such long hoses, such as the waste not being able to travel that far in the hose, causing a flood.

I just wanted to see which option people would recommend, and if the drawbacks I have found in my research are actually correct.

I am a novice with plumbing so apologies if I've used any incorrect terms.

FWIW the dishwasher is a Hotpoint Aquarius, I am guessing its about 4-5 years old

Below are 2 crudely created paint pictures to help illustrate my options

Many thanks in advance

Josh

 

[just pumps]

Take option 2. Just make sure that you don`t run both machines at the same time and you will be fine.

 

[joshreade]

Take option 2. Just make sure that you don`t run both machines at the same time and you will be fine.

Thanks, am I right in regards to the T-splitter and Y-merger to hook it up?

 

[just pumps]

If using a T to split the water supply then ensure whatever you use is full bore (some have a reduced size bore), if the washing machine outlet goes inside an upstand pipe (white plastic 32mm) then consider upgrading this to 40mm as far as you can then just drop both outlets inside the upstand, wouldn`t join them together in case of any backwash from one to the other.

 

[Madrab]

If your water pressure can't deal with both appliances on at once, then doesn't really matter where you fit it as chances are they will both be on the same pipe anyway just a bit further apart. The inlets on a WM and DW are flow restricted and as long as you have adequate pressure then it's should be able to run both at the same time but you don't mention anything about your mains dynamic pressure and flow.
The waste shouldn't be an issue, I'd guess it's already a least a 40mm pipe and trapped? Just make sure there is a trap and fit a double spigot with a section of pipe above or an AAV to vent the run to minimise any issues if they both drain at once.

 

[joshreade]

Thanks for your reply. I probably wouldn't need to run both at once, but its nice to know I would be able to if I needed. I'm not sure about my mains dynamic pressure and flow, I don't even know what that is lol.

The waste goes into the white pipe as shown in the photo below, I measured it across as 40mm. It grey pipe was placed pretty loosely inside, I'm guessing thats normal.

There is a small trap at the bottom of that white pipe, so is it a case of I can get away with the current trap and one of these:

And if I have problems I should upgrade to one of these?


This is my inlet:

So am I right in thinking I need one of these?

I have read up that the copper (or brass, I forget) ones are a lot better than the plastic ones and less likely to leak.

Sorry about all the pictures and thanks for helping me out

 

[Madrab]

Whooooa ..... Josh

With those pics, you're away playing with malleable fittings and all sorts

If you are going to plumb them into the same cold feed then use one of these to split to the cold inlets of the DW & WM, Make it brass so it lasts

Then one of these, from McAlpine, for the outlets to the top of the washing machine trap

 

[lavo-1]

The Plastic version "Y" piece is fine as the brass will add nothing to the set up. The Y for the outlet is something I wouldn't trust either as you get a lot of fat pumped out of you DW and you get fibres from you WM , so with them combining at one point could spell problems. I would use a standard push fit elbow and a T piece half spliced in just below the midway of your existing stand pipe as this will give more clearance for both waste products.
Sorry to pull down the above post, but I was a service tech for a well know German Appliance company for 20 years and I known what looks a good install to a plumber/kitchen fitter, isn't always a good long term solution.

 

[joshreade]

Thats great thanks. I shall get those 2 things ordered. Stupid question but how does the waste pipe attach to that plastic outlet thing? Does the outlet hose fit over the thinner bit that's pointing upwards, it doesn't look like it will slide inside it.

 

[joshreade]

The Plastic version "Y" piece is fine as the brass will add nothing to the set up. The Y for the outlet is something I wouldn't trust either as you get a lot of fat pumped out of you DW and you get fibres from you WM , so with them combining at one point could spell problems. I would use a standard push fit elbow and a T piece half spliced in just below the midway of your existing stand pipe as this will give more clearance for both waste products.
Sorry to pull down the above post, but i was a service tech for a well know German Appliance company for 20 years and I know what looks a good install to a plumber/kitchen fitter, isn't always a good long term solution.

Ah now I'm confused. Its times like this which I debate just getting a plumber in to do it :S

 

[lavo-1]

The amount of call outs I have had to combined appliance outlets could have made me a Millionaire if I wasnt working for a company. Trust me, you will have less future problems using the elbow and Tee than the suggested spigot version. A plumber will happily instal the Macalpine version but he isnt around when 12months on you are being charged a call out by your appliance manufacturer because they have had to unblock you waste set up.

 

[joshreade]

The amount of call outs I have had to combined appliance outlets could have made me a Millionaire if I wasnt working for a company. Trust me, you will have less future problems using the elbow and Tee than the suggested spigot version. A plumber will happily instal the Macalpine version but he isnt around when 12months on you are being charged a call out by your appliance manufacturer because they have had to unblock you waste set up.

Out of interest what are your thoughts on my "option 1" from my first post?

EDIT: Just realised I've labelled by drawings wrong. By option one I mean running the extension into the inlet and outlet under the kitchen sink

 

[Steelmasons]

If using a T to split the water supply then ensure whatever you use is full bore (some have a reduced size bore), if the washing machine outlet goes inside an upstand pipe (white plastic 32mm) then consider upgrading this to 40mm as far as you can then just drop both outlets inside the upstand, wouldn`t join them together in case of any backwash from one to the other.

Two washing machine waste hoses won't insert into a 40mm standpipe..
Each machine should utilise its own stand pipe....industry gone to the dogs..

 

[Steelmasons]

The waste goes into the white pipe as shown in the photo below, I measured it across as 40mm. It grey pipe was placed pretty loosely inside, I'm guessing thats normal.
View attachment 100978

Waste hose requires an air break..

 

[joshreade]

If using a T to split the water supply then ensure whatever you use is full bore (some have a reduced size bore), if the washing machine outlet goes inside an upstand pipe (white plastic 32mm) then consider upgrading this to 40mm as far as you can then just drop both outlets inside the upstand, wouldn`t join them together in case of any backwash from one to the other.

Two washing machine waste hoses won't insert into a 40mm standpipe..
Each machine should utilise its own stand pipe....industry gone to the dogs..

With that in mind.... do you think I am better off with the extension running to the kitchen tap outlet? If seems like the easiest solution but means there will be about 3 metres of hose for both the intake and waste and I'm not sure if thats too much?