Vailant ecotec pro 28 boiler leaking and loosing pressure to 0.5

[Rytis]

Hello everyone,

First post, so apologize if I am not providing enough information.

Pressure in the CH dropped overnight after topping up in the evening. Seems that there is a leak behind the circulation pump. It looks like some kind of a valve. Do I need to replace full pump or the part at the back is sold separately.

I would be grateful if somebody could give any advise.

Regards,

Rytis

 

[terryplumb]

That is an auto air vent , and it needs replacing.
It may not be the only source of pressure loss .

 

[Rytis]

Thank you very much!
Diverter valve seems to be clean.