order the fan ass and when it is changed carefully check inside the heat exchanger for any leaks(common fault on poor boiler)fan is easy to change but should be done buy a engineer and a performance test/gas rate or burner pressure done after reassembling.if it was my boiler i would change spark electrodes at the same time as these are the main cause of noisy ignition(booming)when lighting
jim
February 2009
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