On 01/01/14 11:50, Peter & Jeanne wrote:


"Tom Gardner" wrote in message ...


I've had to do that with mine, possibly as a result of brownouts.

Worryingly it failed while on. Memo to self: ask manufacturer
which protection mechanism would have prevented my house burning
down

Was it not in failed off mode - thus little danger at all ?
I do not see how it can can be considered as failed if still on !!

Changing the thermostat so that the aiming temperature was below
the room temperature should have caused the boiler to stop heating.
It didn't: the heating continued.

Niether of the external controls (on/off and water temperature)
caused any change.

Turning the power supply off at the wall spur connection
restored normal operation.

Conclusion: internal microcontroller was more than a little
confused. /If/ all safety cutouts relied on the microprocessor
then there would have been a very serious problem.