1. Is the electricity supply to the system switched on? Check the fuse in the spur box. If you change it, use a 3-amp fuse only.
2. Does the clock show the right time? Has the clock been on long enough for the boiler to heat the water? If you run water while the clock is in an 'off' period the hot water isn't replaced. 3. If you have a cylinder thermostat/thermostatic valve, is it set at the temperature you require?
4. Is the Natural Gas turned on? 5. If your boiler has a Natural Gas light, is it lit? Always relight in accordance with the instructions on the boiler. 6. Is the boiler thermostat on the setting you require?