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I have 15yr old ferrolli combi 700 optima. when turning on the hot water the boiler fires up and we get hot water but then it goes cold. We can hear the boiler keep firing every 30 secs or so and water gets hot then cold then hot then cold..... really annoying when showering!! please can anyone help solve this problem or do i need a new boiler. CHEERS. :x

i have the same problem with my worcester 28cdi can some one help

[quote="kevyngriffiths"]i have the same problem with my worcester 28cdi can some one help[/quote]
your problem will either be the burner pressures, the hot water thermistor or the dhw plate heat exchanger