Worcester combi boiler dripping through key

Question

Our Worcester combi boiler is dripping from the filling key after I increased boiler pressure. It is very tiny dripping but seems not stopping with key in any position. Is there anything I can do to stop dripping?

David · Answer

The keys should actually be left out and when removing you will have a small amount of water come out. If after the key is removed if you are still getting a small leak you may have to have the Integral Filling Link Charging Link Assembly (thats the bit the key goes in) replaced. The part would cost on average about £30 and can be a bit of a pig to get the old one out but it is a pretty striaght forward job but has to be carried out by a Gas Safe Regesteried person. I say its about an hour to hour and half job and labour cost will vary but would guess at around £80.

Hope that helps.

Dave

Thomas · Answer

The filling loop is faulty  it will need replacing  by a gas registered engineer

Fred · Answer

The internal filling device will have to be changed as
the seal is leaking.

Saleem · Answer

Hi it seems most likely you will need filling loop replacing.  I can't say much without looking at it.

Robert · Answer

Replace washer on the key. Or replace thr filling loop key.

Lee · Answer

It sounds like the internal filling key on your Worcester combi boiler isn’t fully sealing after you’ve topped up the pressure. This is a common issue with Worcester Bosch boilers that use a plastic key for filling. Here’s what you can try:

1. Ensure the Key is Fully Locked
	•	Turn the key to the locked position (usually a quarter turn).
	•	Ensure the grey knob next to the key is fully closed (turn it clockwise).

2. Remove and Reinsert the Key
	•	Turn the key back to the open position and gently pull it down to remove it.
	•	Check for any dirt or debris inside the key housing.
	•	Reinsert the key firmly and turn it to the locked position.

3. Check the Rubber O-Rings
	•	Inspect the key for any damaged or perished rubber O-rings (small black seals on the key).
	•	If they look worn or damaged, replacing the key (around £10–£15) can solve the issue.

4. Slightly Reduce Pressure
	•	If the system pressure is at the higher end (e.g., 1.5–2 bar), try bleeding a radiator slightly to lower it to around 1.2 bar. Sometimes high pressure can cause minor leaks.

5. Replace the Key or Upgrade to an External Filling Loop
	•	If the leak persists, replacing the key is an easy and cheap fix.
	•	If this keeps happening, you might consider installing an external filling loop, which is more reliable and easier to use than the built-in key system.

If the drip continues even after trying these steps, the filling loop valve may be faulty and might need replacing. Let me know if you need further help!

Stephen · Answer

Have you removed the key? Also they are prone to drip when you put them in and remove them the key that is thanks

Lee · Answer

Hello Oto thankyou for getting in touch i would say from previous experience the filling loop would need replacing which is a very simple job and we can install a keyless one which is more easier to top the pressure up and  removes the  key which you have currently if you could send over some photos we are more than happy to send a quotation over and we could get this resolved as quick and tomorrow

Worcester combi boiler dripping through key

Follow Us

Cookies

Manage Cookies

Essential cookies

Analytics & Tracking

Advertising