The boiler will have its own electrical supply - you could turn that off
The boiler will probably have a timer/programmer you could select "off" or "on" sometimes and not other times
The boiler may well have a user thermostat - you might turn it to zero or off
The central heating control may well have a room thermostat device - you could set that to a low setting
You do not mention the make & model of your boiler or the timer control
Your question lacks a certain clarity of reason.
Peccavi, January 2010
