Bleeding a Combi System?

[macman81]

In order to drain down, flush and refill a Sime 80E combi system, is it just necessary to open the main drain cock and the bleed valves on the rads, or are there other bleed valves that need to be opened (on the pump, elsewhere on the boiler?).

 

[ChrisR]

Find the auto air vent on the boiler. As long as its cap is loose, it'll let air in as well as out. Leave it loose always.

 

[macman81]

Thanks, think I've found it. It sits at the back of the pump at top right hand side, small black screw on top (yes, it's already loose)? Sime manual refers to it as the 'air relief valve'.