Sari Gas problem

[yowwox]

Does anyone have a fix or ideas about a Sari Gas Zoom 420 boiler where the frost stat is faulty. The pump and fan cut in during the night and the green frost neon begins flashing. The gas valve does not cut in. When the hot water thermostat is switched off then the boiler close down. Is there a fault on the over heat stat or possibly the frost stat?

 

[Mbear]

U said the frost stat is faulty so why r u asking what's faulty?

 

[yowwox]

Good point !I was guessing it was faulty but have no way of checking.

 

[Mbear]

Do u have zone valves? They may be sticking on

 

[yowwox]

Haven't got any zone valves. The fault seems to be intermittent and will settle when mains power is swtiched off for a few minutes.