Noisy central heating 4 minute cycle

[newsgroup]

Hi I have a problem with my central heating system in that it makes loud noises in the pipes. Almost sounds like a big kettle boiling, but seems to be the pipes near the boiler vibrating. Only started recently and nothing has changed. About 2 months ago changed boiler fan, but it didn't start then. Have timed it and it seems to be noisy for about 3 minutes followed by

1 minute of quiet running. Not sudden on/off of noise but a gradual build up/calm down. Another problem is that often the boiler cuts out (overheat light) and you have to turn it off/turn it on again. Its a 10 year old baxi. Could it need descaling ? If so, is the only solution a corrosive descaler in the system ? Cheers

[John]

It could be that your lockshield valves need opening a bit to increase the flow.

John

[Andrew Gabriel]

or the pump isn't working properly, e.g. the impeller blades have come off as happened to a friend of mine.