Boiler leaking after drain and refill

[thepurpleblob]

Today I drained my central heating system to relocate a radiator. Everything went fine and I filled and bled the system. Within a couple of hours, the pressure has gone and there is a pool of water under the (combi) boiler.

I didn't go near the boiler. Where might I have gone wrong??

I'm off to have a good look for the leak.

Thanks.

UPDATE:
Ferroli boiler. At the rear of the pump, there's a black can shaped part with a brass 'lid'. On top of that is a black screw cap. This was a few turns loose. I tightened it up and the leak stopped. I'm guessing this is a bleed screw? I'm a bit confused why it wasn't leaking before.

Should I be concerned?

 

[dcawkwell]

The part you are talking about is the auto air vent.
That vents the boiler of air on filling.
Sounds like it is fault.

Probably ok to leave it screwed down or perhaps vent it again
after a few days running. Ideally replace the part.

 

[45yearsagasman]

That will be an auto air vent and this can sometimes happen after a drain down. The little valve inside has failed to close and the best solution is to replace the valve. Tightening the cap will do for now, but they are normally left loose for the air to escape.

Note to self........must learn to type faster.

 

[thepurpleblob]

That's brilliant (and makes sense) - thanks for the info

 

[conny]

Is this the same as a pressure relief valve?
I have a jaguar combi which has recently been leaking form the back end of the pump. It only leaks when the heating is on. Is it a simple job for a diy'er to replace this valve?
Sorry, not meaning to hijack post

 

[Dan Robinson]

Maybe, maybe not.

Post a picture.