What is this leaking pipe from my boiler?

[leegsi]

I have this pipe dripping outside my house which comes from my combi boiler

 

[Bodd]

That is your Pressure relief pipe.
You could have over filled your boiler above 3 bar...
It could be a over heat problem.

Or an expansion vessel problem.

 

[leegsi]

Just checked and it was over 3 bar.

Not had a problem before and the only thing that changed was the heating came on this morning.

I have reduced to pressure back into the green (When the heating was off and rads were cold) and see what happens.

 

[terryplumb]

Check your filling loop is fully closed.

 

[Bodd]

You might find that the PRV will not seal and will need replacing.

 

[Madrab]

Did you fill up you CH recently?

If it only bounced up to 3bar when the CH came on then it's probably the Expansion Vessel (EV), usually though that would drop back down once the system cooled down.

 

[leegsi]

Not touched it for about 6 months.

There was quite a bit of air in one of the top rads that I bled and that reduced the pressure to the correct value.

No issues this morning but will keep an eye on it (Fill loop is fully closed)