worcester/bosch combi boiler 24cdi


3 Mar 2009
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United Kingdom
i have a worcester/ bosch combi 24cdi boiler, the hot water only works when the heating is on can anyone help to solve this problem or have any sugesstions on why this is happeneing.

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Does the hot water light come on at the front panel? If not its probably the diaphragm needs replacing.
I had the exact problem on my Worcester 28cdi RSF, but after replacing the diverter valve diaphram, I still didn't get any hot water, except when the heating was on. I eventually did some tests from the manual and did get hot water for a while, but just recently it is back to square one. I never did know why it suddenly got hot, so really the problem was never conclusively found. The problem seems to lie with the gas valve. It should give full flame when DHW is demanded, as opposed to the CH which starts with a low flame and increases according to the setting of the temperature valve on the front of the boiler. I'll let you know if I solve my own mystery! Good luck!
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Turn the heating off.
Run a hot water tap.
Does the left hand pipe (C/H flow) heat up?
If it does the diverter valve needs stripping and cleaning (or replacing.)
Nightmare job.
Good luck.......

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