Central heating works but no hot water

[scrivomcdivo]

Good evening all.

I have an Isar HE30 boiler (please don't hold this against me as I know they have a poor reputation). It worked for the first 2 years we lived in our house with piping hot radiators and water. Nonetheless in recent months, the hot water has played up and it has taken a good few minutes at time for the hot water to run hot(ish) before running a bath. This morning however, there is no hot water at all and the water is running freezing cold (not even lukewarm).

I checked the pressure gauge on the boiler and it was at 0 (0.25 when turned on) and so I've topped this up to 1 bar this evening. I think this may have been caused as I bled the radiators the night before last. Hoping this would sort the problem, I've turned the boiler back on and let the hot tap run for a good few minutes but it is still running ice cold. The radiators are still running piping hot and so the boiler does seem to be firing up and working fine enough to warm the radiators so just unsure why the water is running ice cold.

Any suggestions?

 

[ChrisR]

There's a sensor to notice the water flow then a diverter valve which sends boiler water to heat the tap water in the tap water heat exchanger.

Likely the fault is with one of those!