Cannot drain micorbore central heating

[langers]

Whilst trying to resolve a cold radiator i have discovered that i cannot drain the whole CH system.

I have tried draining from all the radiators on the ground floor but nothing comes out of any of them. There is water flowing trough them as all heat up. I can drain the first floor by draining from one of the first floor radiators.

I have being trying to resolve a blockage on a first floor radiator and have had Fernox F3 in the system for a week - no luck. (was only able to drain half the system in order to do this)

Are both problems related? Any suggestions on how i can drain the whole system so i can fulsh out the F3?

 

[studips]

is this by breaking the joint with the lock shield / trv or by a drain valve? drain valves do get stuck and clog up. have you tried the hammer method of loosening things up?

 

[langers]

by using the drain valves. All three rad's downstairs have them and none work. Have given all of them a good tap with the spanner to loosen any potential debris. Still no luck. Not so much as dribble. They have all worked in the last 3 years as i have removed them all for decorating.