help needed worcester 24cdi

[deacs09]

Hi, I have recently moved into a property that has a Worcester 24CDI combi boiler.
I have had a new gas valve fitted as it was not firing up at first and it appears to be working well enough for Central heating however the hot water is a real issue.
Firstly, the hot water never actually gets hot. it gets quite warm but never enough to burn my hands.
Secondly, if someone is in the shower and another hot tap is turned on, the shower will become freezing cold.(the shower pressure is also quite poor as only hot water can be turned on or the shower is too cold)
Also, as it fails to get hot, when filling a bath it can take 15 minutes or so as i can not put any additional cold water on at the same time and the pressure on the hot taps is quite poor.
The hot water temperature nob was snapped off so i used the c/h one to set the water temp to max but no matter where it is set to it still does not increase the water temperature.
The pressure on the boiler is fine, (set to 1.5 bar)
Any ideas on what it could be and if its a simple fix.

Cheers

 

[Jamespl]

Run a hot tap at half of the full flow rate and have a look on the boiler to see if the red light for hot water is on. If its not then its you diverter valve that needs replacing. If it does come on leave the tap running and see if the burner goes off after a short while and then fires back up again after a few seconds. If the burner goes on and off it might well be your plate heat exchanger that is scaled up or blocked.

 

[dangas123]

It sounds to me like the hot and cold are blending, most probably at the shower. With a hot tap running check your shower to hear if water is flowing through the shower. If you can hear water flowing through the shower you need a double check valve fitted to your hot pipe supplying the shower. Its most likely not a boiler fault.

 

[Jamespl]

The easiest way to test for cross leaking is to turn off the isolation valve on the cold inlet of the boiler and open a tap. If there is a continual flow of water coming out the hot tap then you have cross leaking. If there is no water going into the boiler then non should come out the hot tap. Also feel the hot pipe coming out the boiler. If that's nice and hot then that's also a sign that you have cross leaking. Another thing to think about is are the gas pressures on your new gas valve correct? If they are really low that would cause poor hot water temp.

 

[BARNY78BG]

as jamespl said most likely diverter valve or diaphgram

 

[deacs09]

I tried the tap on half power and the boiler does cut off and then come back on again so I am assuming it is the plate exchanger. How do I go about sorting that out? Is it a simple job. I think I may also need to change the gas flow on the new v alve??

 

[Jamespl]

Did the red light for hot water stay on though or did that go off and on too. You should really get a gas safe registered engineer to look at your boiler rather than messing yourself.

 

[deacs09]

The red light for the water stayed on the entire time however the boiler light was on and off every 15 seconds or so.
I am not going to do the work myself as i have no idea however i was hoping just to get the the cause of the issue so that when I call an engineer i know what to tell him and so that i have some idea what he is saying and suggesting.
It is not a big issue as there is hot enough water for everything i require but it would be better to get this sorted if it could lead to further issues.
I will also get the pressures checked on the gas valve.

What would anyone suggest is the next step?

 

[mysteryman]

Could need a powerflush - see the 28CDi thread.

 

[deacs09]

I think that the best thing to do from here is to increase the gas flow to see if that makes a difference and then also get the plate heat exchanger cleaned out.

I will get those done as soon as possible and let you know the results.
If that does not work then i dont know what to do?

Just as a check, Can this be the cause of the low water pressure in the house as when one tap is on the others will hardly work?