1. How long has it been since the heating system was serviced? It should be serviced annually.
2. Is the programmer set properly - time, on-off settings, summer/winter operation etc?
3. Can the heating and hot water be controlled separately?
4. Is the thermostat on the hot water cylinder at the right setting?
5. Is the main central heating thermostat positioned in a draughty hallway?
6. Has the accuracy of the thermostat been checked recently?
7. Fit thermostatic radiator valves in rooms where lower temperatures are needed.
8. The system may need balancing, or "bleeding" if radiators are only hot at the top.
9. Your old boiler may need to be replaced. Modern condensing and combination boilers are more efficient.
10. Check for draughts around windows, doors and letterboxes and insulate if necessary.
11. Is the loft adequately insulated? About 150mm (6 inches) is recommended.
12. When replacing a hot water cylinder, choose one that is foam insulated by the manufacturer.
13. Anyone working on a gas appliance must be CORGI - Council for Registered Gas Installers registered. Ask to see a CORGI ID card or contact CORGI to check that your installer is registered.