Leaking outside overflow pipe

[SteveM]

Hi, A few weeks ago I got a plumber out to look at my Baxi combi boiler which kept losing water pressure a few times a day and affected the central heating, I`d noticed the outside relief overflow pipe had water leaking out due to the pressure shooting up each time I repressurised the boiler.
He ended up repressurising the expansion vessel and everything has been ok since and the pressure has stayed at around 1.5. What is puzzling me though is that the pipe outside still has the odd drops of water in it each day, the two filling valves seem to be off, is there something else that could be wrong?

 

[Alanc]

I would let your plumber know, he will have a good idea what the problem is.

 

[spanner]

Check it in another few days time to see if it is okay and calling your plumber if it ever persists

 

[JCplumb]

A lot of the time, once the pressure releif valve has activated it develops a bit of a dribble. Your gas engineer will be familiar with the problem and should be able to replace the valve easily.
You say the filling loop valves 'seem' to be off. Remove the loop and you'll know for sure. The regs state that the loop should not be left attached anyway but most people leave them on in my experience.