radiator

[mayna]

i have a combi boiler with 10 radiators ,the ground floor working fine,middle floor fine,but the top floor,the bypass radiator,flow pipes hot,return pipe cold,as well as radiator.
the second rad from top floor is red hot ,the third one is warm and the last one is cold,i took rad out and flushed it,was clean put it back,bled air out but prob is still there.any advice please help,as 3 gas boiler men just don t know.

 

[ChrisR]

See Balancing in ref section.
What floor's the boiler and what pressure is it at?

 

[bab]

3 gas men dont know while on site but weve to guess from here . you dont ask a lot. while the rad was off did u try opening each valve into a bucket to test a supply on flow & return. they must a tried turning all other rads off but this one yeah?