Worcester Bosch boiler: how to turn the heating on

Greenstar 4000

The Greenstar 4000 has a display with a heating key. The heating mode it shows decides whether the heating can come on.

1. Press the heating key. The display shows the maximum flow temperature and the heating mode.
2. Choose On (heating on) or auto (heating follows the times programmed for heating). Off means the heating is off.
3. Set the maximum flow temperature with the arrow keys. It goes from 30°C to 82°C. Worcester Bosch suggests about 65°C for radiators and about 50°C for underfloor heating.
4. Set your room thermostat or heating controller to the temperature you want. Worcester Bosch says the controller's own instructions show how.

From Worcester Bosch's Greenstar 4000 user instructions: Worcester Bosch Greenstar 4000 combi operating instructions (6 720 891 170, 2020/09)

Greenstar 8000

The Greenstar 8000 uses a heating key with the same kind of modes as the 4000.

1. Press the heating key.
2. Choose On (heating on all the time), Auto (heating follows your programmed times) or Once. Off means the heating is off.
3. Set the maximum flow temperature. It goes from 30°C to 88°C. Worcester Bosch supplies it set at about 65°C, which it says suits most homes with radiators, and suggests about 50°C for underfloor heating.
4. Set your room thermostat or heating controller.

From Worcester Bosch's Greenstar 8000 user instructions: Worcester Bosch Greenstar 8000+ user instructions

Greenstar 2000

The Greenstar 2000 has a summer mode. Worcester Bosch says it switches off the heating pump and leaves hot water working, so it's the first thing to check if you get hot water but no heating.

1. Press the heating key.
2. If the summer mode symbol is showing, use the arrow keys to move out of summer mode and press OK. Your manual shows the symbol.
3. Set the maximum flow temperature: press the heating key, adjust with the arrow keys between 30°C and 82°C, and press OK to save.
4. Make sure the programmer or timer is in an on period and the room thermostat isn't set too low. These are the first two checks in Worcester Bosch's own list.

From Worcester Bosch's Greenstar 2000 user instructions: Worcester Bosch Greenstar 2000 combi user instructions (6 721 820 553, 2020/01)

Greenstar i

On the Greenstar i, the programmer and room thermostat switch the heating on and off. Worcester Bosch says that to turn the heating off for warm weather you set the programmer to OFF or turn the room thermostat to minimum, so turning it back on is the reverse.

1. Set the programmer to an on setting or on period.
2. Turn the room thermostat up above the current room temperature.
3. To change the flow temperature, use the central heating adjustment buttons and press OK to confirm. Pressing both buttons together selects Worcester Bosch's economic setting.

From Worcester Bosch's Greenstar i user instructions: Worcester Bosch Greenstar i ErP user instructions

Greenstar CDi Classic

The CDi Classic has an ON/OFF button and a central heating temperature dial. Turned to the frost protection symbol, that dial switches the heating off and leaves hot water and frost protection working.

1. Press the ON/OFF button. Worcester Bosch says the indicator lights blue when the boiler is on.
2. Turn the central heating temperature dial away from the frost symbol, to the level you want. It covers roughly 35°C to 90°C.
3. Set the programmer or timer and the room thermostat. Worcester Bosch says central heating must be controlled by a programmer or timer and a room thermostat.

From Worcester Bosch's Greenstar CDi Classic user instructions: Worcester Bosch Greenstar CDi Classic ErP combi user instructions (6 720 815 728, 2015/05)

Heating still not coming on?

1. Check the programmer or timer is in an on period, and the room thermostat is set above the room temperature. These are the first checks in Worcester Bosch's own list.
2. Check the pressure gauge. Worcester Bosch recommends 1 to 1.5 bar with the system cool. Our pressure checker shows what to do if it's low.
3. If the display shows a code, look it up in our Worcester Bosch code list. EA, for example, means no flame was detected.
4. Going through this for the first time this autumn? See when to turn the heating on, including bleeding the radiators first.