No Heating but Hot water OK

22 Jan 2006
Reaction score
United Kingdom
We have a Vaillant Combi about 7-8 years old. It has been playing up with the heating not coming on with the timer. Hot water is leaking slowly out of the overflow. The hot water alsways works but now the heating will not come on. The boiler is the right pressure, I have tried draining and re-topping up. Re-lit the pilot and it keeps trying to fire up the heating then stops again. If I turn the main heating switch off then on again the pump is constantly running even with the heating off and no hot water triggered. Any ideas as its rather cold?
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It sounds like an earlier 242 with dirt in the system preventing the flow switch working. The dirt is also causing the PRV to leak.

I would advise that you get a professiojnal who is famaliar with that model to deal with all the problem aspects. It could be that the system might need power flushing. Ignoring problems can make the damage worse!

Tony Glazier
Hi guys, hey Simmo I've got the exact same problem you describe on the same Valiant Combi (hot water but no CH) and minor leaking from the pressure relief valve.

How did you resolve yours? what repairs or replacements were required?


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