warm bottom/cold top slowly warms up

[boris]

recently flushed through all rads, replaced,started heating.all fine except end rad,is hotish at bottom, the top becomes warmish after so me considerable time.think rad needs bleeding but cannot find a bleed valve on this rad?????

 

[pannierstan]

Look at the back for a little plastic cap covering the bleed left hand end.

Has the radiator got a round top?

 

[breezer]

if t helps, i have one rad that has the bleed valve on the back (as just mentioned) but it has no cap, but unless you really look hard you wont even know its there