Microbore question

[nellieboy]

Hi, I have a microbore central heating system. Each radiator has both micbrobore pipes going in/out of the same end. Some rads get very hot, others just warm.
Would I benefit by replacing the existing vavles with a TRV in one end and the outlet at the other end of the rad? (I could reach the other end of the rad with either more microbore or 15mm).
OR is there a simple reason/solution to my problem. (it just seems that the hot water comes in and out of the microbore valve without going into the rad).
Also, is there any reason why 11 of the rads have 8mm microbore and 2 have 10mm - there is no extension to the house so all rads are original build.
Any help appreciated.

 

[kevplumb]

either the pipe inside the rad has become disconnected or is to short

 

[nellieboy]

Thanks - once this pipe inside is correctly fitted, is this an efficient design or would I be best replacing it with the inlet and outlet at each end of the rad.

 

[kevplumb]

they do the job ok