Thanks matt1e - silly me - of course it is an auto air vent - I think the success of fixing the controller went to my head !!.
See pic of underside where it failed. The brass bush there is quite thin and the outer case has a large diameter and so overtightenning is easily done. Even hand...
Grant Vortex ECO Utility 21-26. After 3 years use on just now winter start up the factory installed Caleffi PRV (10bar !!!) fractured where it is screwed into the top of the outfeed and so emptied the system water (with Fernox) over the boiler and the control box. There was steam from the...
