Air in hot water cylinder

[Derben]

Hi,

I drained the central heating system to change a radiator and pump. Refilled ok and all radiators bled and also water pump.

I appear to have trapped air in the hot water cylinder (not cylinder to tap) but in the heater coil. I can see what looks like a bleed valve which is located on the end of a pipe running from the coil from the hot water cyclinder (pipe running vertically with a screw end). Is this a bleed valve - trouble is, I can't unscew it as it appears to be well and truely stuck. Broke several flat head screw drivers trying to open it (if it is the bleed valve).

Any suggestions - is there any other way of getting the air out of the hot water heater coil ?

P.S. all radiators okay but since turning pump up, need all bleeding again.

 

[twgas]

try a pair of pliers on the bleed screw if possible.
another try would be to put hot water only on, turn boiler stat right down or off and the pump might push the air through.