Boiler thermostat overiding everything!

[philallen]

I have got a Trianco Eurostar boiler, and have been recently experiencing some weird behaviour, such as, in the middle of the night the boiler switches itself on.

The CH system has a programmer, which is working fine, and a room thermostat which again is working fine. The boiler is located in the house (utility room) and there is no frost stat fitted.

If the system kicks in in the middle of the night, ie even through the programmer is switched off, the only way I can stop it is to either switch of at the mains, or to turn the boiler thermostat right down.

First question is: Is this normal behaviour? (I assume not as I feel the programmer should be the deciding factor) Second is: What can I do about it?

Thanks for your thoughts.

[Andrew Gabriel]

Where is the boiler situated? Could it be an internal (or external) frost stat kicking in?

[robert]

Could be the room thermostat is wired like a froststat and overriding the timer.

If you dont have a froststat consider changing the room thermostat for a 24hr programable one and set a low temp at night to act as a froststat.

Robert