What does a Programmer Do?

A Programmer is a timer switch that allows you to set the on or off times
for both the central heating system and the hot water cylinder.
A programmer is one of the heating controls. It is connected to the wiring centre.

Some programmers have a different setting for each day.
Some have the same setting for Monday to Friday and a different setting for Saturday and Sunday.
Some programmers have the same setting for every day.
Some programmers allow you to switch the heating on outside of the set times
by using an advance or over ride button.
Some have a +1 button to keep the heating on for an extra hour.

To find out how your particular programmer works
look up the manufacturer on the internet and there will often be a user guide on their site.

The programmer will not switch the heating on if it is turned off at the room thermostat.
The programmer will not switch the hot water on if it is turned off at the cylinder thermostat.

A programmer may also contain the room thermostat in the same unit.
This is sometimes called a programmable room thermostat.