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

How to repressurise your combi boiler with an internal filling key

These instructions apply to the following boilers only:

• Worcester 24 CDi
• 26 CDi Xtra
• 28 CDi
• 35 CDi II

Your boiler may have a metal, slatted cover panel on the underside. This will need to be removed by pulling down the front edge and sliding it towards you. The internal filling link assembly, if fitted, is a black plastic moulding on the left hand side.

Please note some older models may use a larger key than the one pictured below. The larger keys do not have any arrows on the shaft, so please ignore references to the arrows if your key is different to the one pictured.

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

2) In order to repressurise the boiler, you will need the white T-shaped filling key.

3) Look up into the bottom of the boiler and you will see a black plastic manifold. It is connected to the DHW (domestic hot water) inlet connection and the CH (central heating) return connection.

4) Locate the white arrows moulded into the shaft of the key and the padlock symbols on the outside of the manifold.

5) Push the key up into the hole in the manifold, with the arrow pointing to the unlocked padlock.

6) If the key is located correctly it will only turn a quarter turn clockwise (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). Ensure that the arrow points to the locked padlock.

7) Now turn the grey knob located to the right of the key gradually to the left (at most a couple of turns). 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 because water may drip out if it is not fully inserted!

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

9) Turn the key back to the original position and remove it, a small dribble of water is normal here.

10) Store the key in the clip on the inside of the bottom panel or another safe place.

11) You may need to repeat this process if you now bleed the radiators.

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