cold air pump radiator

[BGSMITH]

have an air pump heating system, but one radiator is cold all the time, tried to bleed it and there was water there instantly that looked clean so checked the thermostatic valve the plunger seemed to move freely. What do i try next?
any help appreciated

 

[Harry Bloomfield]

What do i try next?

Turn all the other radiators to off, except the one which is at the moment cold, then run the heating system. Are you sure the valve, at the other end to the TMV is open?

 

[BGSMITH]

thanks for replying
i will try that
i ve tried running with the valve at the other end halfway open in case its marked the wrong way round

 

[Justin Passing]

What's "air pump" about it?

 

[BGSMITH]

air heat pump