How do I repressurise my combi boiler with an internal filling key ?

The video below shows you how to repressurise the following combi boilers:

• i Junior
• Greenstar i Junior (if fitted)
• Greenstar Si (if fitted)
• Greenstar CDi combi

These instructions are for the following boilers:

• i Junior
• Si II
• Greenstar i Junior (if fitted)
• Greenstar Si (if fitted)
• Greenstar CDi combi
• Greenstar Highflow CDi

1) Ensure the power to the boiler is turned off and the heating system has cooled down.

2) If necessary, remove the cover-plate from the underside of the boiler, as shown in the image below:

3) Locate the white T-shaped filling key (it will normally be clipped to the bottom panel of the boiler).

4) Look up into the bottom of the boiler and you will see a black plastic manifold, as highlighted in the image below. It is connected to the DHW (domestic hot water) inlet connection and the CH (central heating) return collection.

5) Insert the key into the hole in the manifold (there is a ‘padlock’ symbol on the plastic body- line up the arrow on the shaft of the key with the ‘open padlock’ symbol).

6) Turn the key to line up the arrow on the key with the ‘closed padlock’ symbol, to ensure that the key is fitted correctly try to pull it straight down when in the locked position and it should stay in place.

7) Now turn the white knob on the side of the key gradually anti-clockwise. You will hear the water start to flow (the more you turn the knob, the faster the water will flow).

Please ensure the key is fully inserted, water may drip out if it is not fully inserted!

8) Observe the pressure gauge; when it reads approximately 1 to 1.5 bar, turn the white knob back to the fully in position to stop the flow of water into the system.

9) Turn the key back to its ‘unlock’ position and remove it by pulling the key downwards- a small amount of water will be spilt. If water continues to drip from the hole the key was fitted into, turn the grey/white knob another half turn clockwise. Store the key in the clip on the inside of the bottom panel or another safe place.

This process may need repeating should you now bleed the radiators

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