A room thermostat senses air temperature, when it falls below the required setting the room thermostat will switch on the heating.
A programmable room thermostat is both a programmer and a room thermostat. A programmer allows you to set 'On' and 'Off' time periods to suit your own lifestyle. A programmable room thermostat lets you choose the time to switch on the heating as well as the temperature you would like maintained. It will allow you to select different temperatures in your home at different times of the day (and days of the week) to suit your plans. The programmer's timer must be set correctly for this purpose.

Turning programmable room thermostats to a higher setting will not make the room heat up any faster. How quickly the room heats up depends on the design of the heating system, for example, the size of boiler and radiators.
Neither does the setting affect how quickly the room cools down. Turning a programmable room thermostat to a lower setting will result in the room being controlled at a lower temperature, and saves energy.

Programmable room thermostats must be used correctly to enjoy their energy saving benefits - find the lowest temperature settings that you are comfortable with at the different times you have chosen, and then leave it alone to do its job. You can further control temperatures in individual rooms by installing thermostatic radiator valves (TRVS). Remember, a programmable room thermostat need a free flow of air to sense the temperature, so they must not be covered by curtains or blocked by furniture.

A cylinder thermostat switches on and off the heat supply from the boiler to the hot-water cylinder. It senses water temperature inside the cylinder, switching on the water heating when the temperature falls below the thermostat setting, and switching it off once this set temperature has been reached.

As with a room thermostat, turning a cylinder thermostat to a higher setting will not make the water heat up any faster - this is dependent on the size of boiler and the heat exchanger inside the cylinder. The cylinder thermostat will not always switch the boiler off, because the boiler sometimes needs to heat the radiators.

A cylinder thermostat is usually fitted between one quarter and one third of the way up the cylinder. The cylinder thermostat will have a temperature scale marked on it, and it should be set at between 60C and 65C, then left to do its job.
If you have a boiler control thermostat, it should always be set to a higher temperature than that of the cylinder thermostat. In most boilers, a single boiler thermostat controls the temperature of water sent to both the hot-water cylinder and radiators, although in some there are two separate boiler thermostats.