Ariston SX20 boiler is fine in central heating mode but when the hot tap is run it fires up then 10 seconds later main burner goes out then 5 - 10 seconds later it fires up again and this continues. Consequently water does not get hot just luke warm. Diverter valve is lifting ok. Very grateful for any suggestions?
Update - just tried the central heating and that is also tripping in and out - i.e. burner going on and off
Update - just tried the central heating and that is also tripping in and out - i.e. burner going on and off
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