Poor hot water pressure - dishwasher not working.

[dcb0]

Hello All,

We've recently had a new bathroom suite and new kitchen installed. There were no changes to the water supply plumbing in the bathroom, but there were some changes in the kitchen in order to provide a hot water supply for both the dishwasher and the washing machine.

The main symptoms are a low rate of hot water flow through the mixer tap in the kitchen, and that the new dishwasher doesn't seem to bring in enough water to operate. It does seem to have a little in the bottom at the end of trying a wash program, but the top of the machine, inside is still dry. So it seems that there isn't enough pressure to make the sprays operate. It's an Ikea Renlig DW45, and the installation manual says that it needs a minimum of 0.3 bar water pressure to operate.

We have a fairly new (1 year old) combi boiler, an immersion heater tank, with a cold water tank above it. Any suggestions about the cause of the problems, and possible solutions?

Many Thanks,
David.

 

[Dan Robinson]

fairly new (1 year old) combi boiler, an immersion heater tank

You mean condensing boiler?

 

[HERTS P&D]

Hello All,

We've recently had a new bathroom suite and new kitchen installed. There were no changes to the water supply plumbing in the bathroom, but there were some changes in the kitchen in order to provide a hot water supply for both the dishwasher and the washing machine.

You must have old machines because all new ones are cold fill only. The only thing I can think of is that there is debris in the pipe work.

Turn off supply to washing machine and remove hose from rear of machine, place end of hose in a bucket and turn on the valve. Does water come out with any force? You could have blocked filters which are in the end of the hoses.

Failing that call your plumber back.

Come back to us and let us know what happens.

Andy

 

[HERTS P&D]

Hello All,

We've recently had a new bathroom suite and new kitchen installed. There were no changes to the water supply plumbing in the bathroom, but there were some changes in the kitchen in order to provide a hot water supply for both the dishwasher and the washing machine.

You must have old machines because all new ones are cold fill only. The only thing I can think of is that there is debris in the pipe work.

Turn off supply to washing machine and remove hose from rear of machine, place end of hose in a bucket and turn on the valve. Does water come out with any force? You could have blocked filters which are in the end of the hoses.

Failing that call your plumber back.

Come back to us and let us know what happens.

Andy

 

[Dan Robinson]

Thinking about it - I can't think I have ever seen a domestic dishwasher with hot fill....


Still, could also be an air lock - assuming we are not talking combi boiler.

 

[dcb0]

Thanks for these ideas!

You mean condensing boiler?

Yes it is a condensing boiler. It supplies hot water for the taps and for the central heating.

You must have old machines because all new ones are cold fill only.

Yes the washing machine is old, and has both hot and cold fill. The dishwasher is new and I thought that it would be cheaper to run if it filled with hot water rather than having to heat up cold water with electricity. The installation instructions don't indicate whether hot or cold is required.

Does water come out with any force?

Well, there is a steady flow, but not much force. At the hot tap the flow is slow, and I can easily stop it just by putting my thumb over the end of the tap. I can't do that with the cold, as that's at mains pressure. I'll check what the pressure is like at the washing machine and dishwasher inlet taps, but it may be a few days before I can do that as we are moving into the flat at the moment. I'll let you know what I find.
Thanks again.
David.

 

[Dan Robinson]

On one hand you say you have a combi, on the other you have a hot water tank. Can you confirm your boiler heats the hot water instantaneously, or that it is fed from the tank?

How many pipes come out of the bottom of the boiler?

 

[WedgeAntillesRed2]

Sounds like your new kitchen taps probably have 12mm flexi-pipes or possibly 15mm but are kinked. Check under the sink.
Dishwashers are mains cold feed so any hot water supplied to it on a conventional system i.e; storage tank in roof with hot water cylinder simply will not have enough pressure to get past the solenoid valve on dishwasher.

 

[dcb0]

How many pipes come out of the bottom of the boiler?

4 copper pipes, two large, and two small ones, and one plastic pipe which is connected to the waste water pipes. Sorry: I've not been using the correct terminology for the boiler. I thought that a combi boiler was simply one that provided hot water to taps and to the central heating system.

Sounds like your new kitchen taps probably have 12mm flexi-pipes or possibly 15mm but are kinked. Check under the sink.

I've checked under the sink, and there are flexi-pipes, but they aren't kinked. I can't tell what size they are inside, but I think that the internal diameter of the holes in the tap, where the flexi-pipes screw into the tap, is less than 12mm.

Dishwashers are mains cold feed so any hot water supplied to it on a conventional system i.e; storage tank in roof with hot water cylinder simply will not have enough pressure to get past the solenoid valve on dishwasher.

OK, I guess that I'll have to change the supply to the dishwasher to cold water. If we did have a combi boiler, would that give enough pressure to the hot water supply for the dishwasher to operate? The dishwasher is very close to the existing boiler. Not that I'd consider that for the moment, unless it were considerably cheaper to run.

Many Thanks, David.

View media item 42075

 

[WedgeAntillesRed2]

Thats an interesting picture if not good quality.
By the looks of it that flexi connector is a filling loop used to pressurise the central heating system. Iam guessing you have a conventional storage system with pressurised heating system.
If you can clarify boiler make and model we can tell you exactly what system you have and give you a better diagnosis.
Could you take a photo of boiler and under the sink unit?

 

[algas]

My dishwasher works of the low pressure hot supply check the filter on the inlet isn't blocked also if there is a restrictor remove it !

 

[dcb0]

algas: That's very encouraging. I know that there is a little red plastic filter in the inlet to the dishwasher. I'll look for a restrictor too.

I'll take better photos too. This is just a little "zoomed - in " bit of a photo of the kitchen which is why the quality is so poor.

Thanks for all you help, it's much appreciated.

 

[dcb0]

Here are the photos that have been requested:

The front of the boiler. It looks as though the boiler is a Vokera Mynute 20HE, if that's a model number.
View media item 42104
A clearer view of the pipes that come out from the bottom of the boiler.
View media item 42102
The pipe work under the sink.
View media item 42103

 

[plumberdan]

the flow rate through the tap is probably due to the tap, ikea are s**t. imagine running a hose pipe and the waters not running that fast nip the end hey presto its an illusion less flow more pressure but you'll think its great cause its firing out.

 

[plumberdan]

cheaper to run from the cold supply and let the appliance heat the water, then you dont fill how ever many meters of hot pipework with hot water that wont get used.