My thermostat is set to 25 which is higher than the current temperature but my heating system is not firing up.. we have hot water - the boiler is a Micron - the heating timer is set to "on" on the program setting, and so is hot water which is fine but we have no heating, it was on earlier and went off and we can't get it to come back on again, we've even tried turning thermostat to 30 and even though it clicks to suggest the temperature level it still does not fire up the heating.. please help we will be very cold!

Best bet for that unit is to call for service. There are no used serviceable parts to adjust just replace. This unit is somewhat complex for the homeowner to work on. You might try to turn the heat timmer off but that is about the most you can do.