Combi-Boiler Issue on Hot Water

13 Jan 2009
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United Kingdom

I have a Biasi 24S combi boiler. I have noticed a small issue lately. Only if 2 hot taps are on or shower & hot tap, etc will the flame ignite to heat the water. The flame ignites fine on the timer for the central heating and therefore heats the water during this period. But when the heating is off the flame won't light for just one tap on.

It's running at just over 1.2 bar which according to the manual is right.

any ideas?

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Do these have a diaphragm? If so it has become perished, weak, or even have a split in it.

If no diaphragm check the flow switch is operating correctly and that the inlet filter on the cold mains to the boiler is clear.
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Could also check when ch is off and cold, that when hot tap is used ch flow doesn't get hot.

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