Hot/Cold/Lukewarm water from combi boiler

[Lisa McKinney]

I posted here before several months ago but didn't manage to get the issue resolved due to not being able to test different things.

I have a flat on 3 floors:

1st floor - full bathroom, bath with separate shower, toilet and sink
2nd floor - shower room with electric shower, toilet and sink, kitchen with sink and this is where boiler is located
3rd floor - full bathroom with bath and electric shower, sink, toilet

Boiler is a Worcester Greenstart 42cdi classic.

The water is VERY temperamental.

Having tested it just now, I get luke warm water out kitchen sink and bathroom sink on 2nd floor individually. When I run both together, I get steaming hot water in bathroom sink but freezing in kitchen sink.

Downstairs, shower is lukewarm. When I run sink tap, that will get luke warm (I think, might have been hot) but shower will go freezing.

Upstairs bath is usually temperamental and will run luke-warm after being hot for about 10 seconds. If I turn kitchen tap to hot, bath upstairs will run nice and hot.

Temperature on boiler display ranges between 51-66 depending on if taps working.

There are 5 pipes below boiler. From left to right, temperature to touch is:

1 - room temp
2 - very hot
3 - room temp
4 - very hot (but about 5 mins ago was VERY cold)
5 - cold

Heating is perfect - absolutely no problems.

Had a few people look at it. Had the diverter valve changed however this did nothing and I think the heating company just wanted to charge for something as they didn't test if it was faulty.

It's been suggested that it could be a fault at one of the mixer outlets - could this really have such a huge impact on ALL water outlets??

Also suggested it "might" be the shower cartridge on 1st floor (all others are electric showers).

I'm hesitant to pay to have things done which may or may not actually solve the problem.

I haven't been able to determine flow as yet.

From Google, a couple of things come to mind. Something to do with a flow switch or a heating exchange. That's just from answers given on similar problems.

I'm not going to be trying to change anything myself but would be great if someone knew from this info what was likely to be the problem and why, so I can finally try and find a competent plumber to resolve once and for all.

Any help much appreciated.

 

[Lisa McKinney]

Should also say, the light on the boiler comes on and stays on.

Also realised pipe 2 and 4 are the water in/out pipes and when water is running, 2 is very hot, 4 is very cold which I imagine is fine and how it should be.

 

[sammathias]

If you are purely drawing off hot water and don't have the heating on...then only one pipe from your boiler should be getting hot.

 

[Scott_D]

Sounds like the hot and cold are mixing

 

[Gasmk1]

does look like you have a problem with one of your mixers passing possibly shower