Boiler switching on and off frequently during the night

[kj523]

I have an Alpha CB28 combi boiler. It comes on frequently during the night for about 30 secs, then goes off again. This can happen as frequently as once every 3 minutes. Have checked there are no dripping taps, and that the thermostat is turned down, but it still happens. In fact, the other evening it was switching on and off during the evening when the central heating was still on. It still happens even when the boiler is set to hot water only. You can hear the radiators coming on, and they feel slightly warm. Have resorted to switching the boiler off at the mains overnight, as I can't get a decent night's sleep!

Called out a British Gas engineer, who changed the thermostat and a switch, but this has not made any difference.

Am beginnig to think I'm going mad, but this can't be right, can it?

Any suggestions would be welcome.

 

[Deleted member 105431]

could be the frost stat kicking in? It has been very cold.

 

[kj523]

Could be, but would there really be a need for it to come on every few minutes? I wouldn't have thought the water temp would cool from 40 degrees to 8 degrees that quickly? But I could be wrong!