Combi Boiler, only luke warm hot water

[sjones]

I have a Heatline S30 combi boiler. Up to last night everything was fine. Today only luke warm hot water. The central heating is fine, water heated to around 80 degress according to its bar graph temp gauge, but when turn on hot tap only gets luke warm water and temp guage shows around 40/50 centigrade, doesn't matter whether heating is on or not. The boiler does not seem to be trying that hard either, not full gas output. Have checked the gas regulator pressure via the cooker hob and starting boiler, no drop in hob flame so pressure seems OK , any more ideas ? Thanks.

[John Stumbles]

Is the central heating flow pipe getting hot while the boiler is delivering hot water? That would indicate a diverter valve problem (assuming your boiler is a type with a diverter valve and Plate Heat Exchanger rather than combined gas/water heat exchanger heating DHW directly).

[sjones]

Thanks, don't think so but will confirm tonight when home again and heating off!!!

[Ed Sirett]

The modulator might have gone belly up - but your idea is the more plausible.

[sjones]

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I have checked the central heating pipes and they are not getting warm. The temp of the water going in is 10 cent and coming out 35. According to the manual the water temp should be between 35 and 65 centigrade. The hot water thermocouple is about 8k when water on and

20k at 10 centigrade with cold water. How can I check the gas modulator or should I leave this to a central heating guy, and do I need someone that specialises in Heatline boilers? Thanks

[Ed Sirett]

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The details or at least some clues will be in the manual. If those aren't clear then leave the job to a pro. The fact that you have narrowed it down somewhat is a big start.

[sjones]

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to be the non return valve in one of the showers stuck, so hot water was being mixed with cold. Nothing wrong with boiler! After mucking round with shower it cleared itself with a clunk! Thanks