Press the YES button, and you’ll see ON1, the start of your first heating period. Adjust it in 1-minute steps using the – and + buttons. If the – and + buttons are held down, the time changes in 10-minute steps.

Sometimes you might need to change the way you use your system temporarily – perhaps due to an exceptionally cold day. one for central heating and one for hot water. They allow you to switch either on or off, irrespective of the program. So if the heating is off, and you want warmth now – press Advance to switch it on, and it will stay on until the end of the next OFF period. Or if the hot water is on and you don’t need it, press Advance and it will go off until the beginning of the next ON period. You need to set the timings in sequence – i.e. ON1, OFF1, ON2, OFF2, ON3, OFF3. If you get out of sequence, the display will flash a warning.If the engineer hasn’t set your timings for you, your programmer will work with a standard program that has been set at the factory. If this doesn’t suit you, it’s very easy to change it – when you’ve read this introductory section, simply go to the section that contains your programmer model. To further simplify the process of interpreting the wiring diagram, most diagrams also have arrows indicating which wire from each component should be attached to the power source. This also helps to ensure that all components of the system are securely connected.

You can’t set ON1 as the last timing before midnight, but you can set OFF3 after midnight – providing it’s not more than 23 hours and 59 minutes after ON1. On each side of the display there are four operating modes – one group for central heating, the other for hot water. You can change modes with immediate effect by using the appropriate SELECT button. This won’t alter the timings in your program, which you can return to by selecting TIMED. When you press SET? after setting OFF3 for the central heating, the display will ask ‘SET HW PROG?’. The next two components are the room thermostat, which controls the temperature of the rooms, and the hot water thermostat, which regulates the temperature of the hot water in the house. The room thermostat is usually mounted on the wall, while the hot water thermostat is usually placed in the airing cupboard.timings at the weekends, with central heating and hot water working independently for up to 3 heating periods each day.