Central heating ok but no hot water

[Mr M]

I have a Worcester Bosch 240 combi boiler, which has been working fine up until now . The central heating is working correctly.

When the hot tap is turned on, the burners fire-up and remain burning until the demand for hot water is terminated but the water out of the tap is only 'luke warm', whereas previously, the water was piping hot.

I would really appreciate any direction on what the likely cause/causes of this problem could be. Many thanks.

 

[bengasman]

run the water and check if the flow pipe gets hot, if so the diverter is failing

 

[Mr M]

Thanks for your reply bengasman.

Excuse my ignorance but is the flow pipe which you are referring to the 15mm copper pipe "domestic hot water out" which runs from the boiler and feeds the hot water taps

 

[bengasman]

Flow pipe is normally 1 of the 22mm pipes.
Not to worry if you are not sure which is what or why, easy to find out.
Best option, download the manual.
Make do method; turn heating of for half hour. Should have 3 big pipes. The one that stays cold no matter what is the gaspipe. Turn heating on briefly and feel the big pipes, the one that gets warm first is the flow. Turn heating off again and wait a few minutes.
Turn hot water on and check newly found flow pipe

 

[Mr M]

I don't have a manual but I will have a look on Worcesters wesite in a mo. Just to clarify, looking at the boiler from the front the pipes from left to right are as follows:-

22mm Central Heating Flow
22mm Central Heating Return
15mm cold water in, feeding the boiler
15mm hot water out, to taps etc
15mm PRV Outlet
15mm Gas supply in

As I said earlier, the problem is not with the central heating, this works fine and both 22mm central heating (flow and return) pipes are hot. Its the domestic hot water which is only 'luke warm'

 

[wiggikins]

Hi Mr M

I think that what Ben is trying to impart to you goes as follows,
1) Turn down your heating thermostat
2)Open ahot water draw off and allow to run for acouple of mins
3)Feel the C. H. FLOW Pipe for temp rise
4)If flow pipe warms up = Diverter Valve is the culprit!!


Keith.

 

[bengasman]

4)If flow pipe warms up = Diverter Valve is the culprit!!


Keith.

Isn't that what I said in my first reply?

 

[Mr M]

Hi Mr M

I think that what Ben is trying to impart to you goes as follows,
1) Turn down your heating thermostat
2)Open ahot water draw off and allow to run for acouple of mins
3)Feel the C. H. FLOW Pipe for temp rise
4)If flow pipe warms up = Diverter Valve is the culprit!!

Keith.

Ahhh......the penny has now dropped. Many thanks. I'm not at home at the minute but I'll try it out tomorrow and report back.

 

[Mr M]

If the diverter is failing, can I just replace the diaphragm on the inside, or do I need to replace the whole unit. If I replace either/or, do I still need to fully drain down the c/h system or can I just turn the valves on the c/h flow and return pipes.

How much should I be paying (supply only) for a) the diaphragm and b) a whole new unit . Cheers

 

[wiggikins]

4)If flow pipe warms up = Diverter Valve is the culprit!!


Keith.

Isn't that what I said in my first reply?

Absolutely,it was as clear as a bell to me ,but i'm in the game,just thought it needed putting in simple step by step format for the OP
who is obviously "joe public" . Just trying to be constructive!

 

[Mr M]

Hi Mr M

I think that what Ben is trying to impart to you goes as follows,
1) Turn down your heating thermostat
2)Open ahot water draw off and allow to run for acouple of mins
3)Feel the C. H. FLOW Pipe for temp rise
4)If flow pipe warms up = Diverter Valve is the culprit!!


Keith.

OK, I have now done the above. C/H Flow pipe is stone cold

 

[ollick]

This sounds exactly the same as the situation I am in. I have a Falcon II FER Combi boiler that is heating the house fine but only giving off luke warm intermittent (sp) hot water.

I have got the manual out and identified the DHW and CH pipes and it does seem to tie in with whats been said (having ran the HW and turned the CH off to check the warmth of the pipes) and it looks like a Diverter Value problem.

Where's the blinking diverter valve?

Is it part of another piece of the boiler? It's just that looking at the diagram I've got in the manual, the DHW and CH pipes appear to be split deep inside the boiler so I can't see which part holds the diverter valve.

I was hoping that it'd be a nice big box with a large arrow saying DIVERTER VALVE HERE however I'm not that lucky.

Any advice would be really welcome, thanks in advance.

PS, Hope it's all going well Mr M!

 

[Mr M]

Hi Ollick,

I think that I have established that my problem is not related to the Diverter valve. Would you mind posting seperately on the problem you are experiencing, as I do not want my original post to turn into a lengthy 'diverter valve discussion'.

Please don't take this the wrong way, but I just desperately need to get my hot water or the lack of it, sorted out.

Cheers matey and the best of luck with yours BTW.

 

[wiggikins]

Hi Mr M

I think that what Ben is trying to impart to you goes as follows,
1) Turn down your heating thermostat
2)Open ahot water draw off and allow to run for acouple of mins
3)Feel the C. H. FLOW Pipe for temp rise
4)If flow pipe warms up = Diverter Valve is the culprit!!


Keith.

OK, I have now done the above. C/H Flow pipe is stone cold

Probably looking at a clogged up plate heat exchanger then !
Check F.A.Q's for solution Keith.

 

[ollick]

No problems, good luck.