Features a service interrupter to alert householders when the boiler service is due. Warning period starts 30 days before the boiler is due to be serviced. During this time the backlit display flashes and displays the service date. All buttons/programming features are fully functional during this time. If the boiler is not serviced despite the warnings, the programmer will then reduce the temperature level in the property to a safe but uncomfortable level until serviced. Also features a battery back-up. 4, 5 or 6-Wire Installation Fits Standard UK Backplate 5/2 Day Programmable 1 Pre-Set Programme 2 or 3 On / Off Periods per Day Boost Facility Without Holiday Mode Backlit Digital Display 4, 5 or 6-Wire Installation Fits Standard UK Backplate 5/2 Day Programmable 1 Pre-Set Programme 2 or 3 On / Off Periods per Day Boost Facility Without Holiday Mode Backlit Digital Display