Best way of removing air lock in combi heating system?

[jfk]

Hi ive recently drained down my central heating system fed by a combi boiler. Unfortunatly 2 radiators dont work downstairs, their pipe runs drop down from upstairs where all rads work. I have bled the radiators and they are both full. Im presuming their is an airlock, what is the best way of removing this and rectifying the problem?
Cheers J

 

[Gasguru]

Try turning all the other rads off.

 

[seco services]

try shutting all the rads that work letting full flow go to them that don't.

 

[jfk]

ok if that dousnt work what else can I try

 

[seco services]

are they both on the same drop downs.

 

[bengasman]

Never seen a pressurised combi without a pump problem that had an airlock that would not shift.