Radiators not all getting to temperature after fitting new boiler

[RoyLittle0]

Hi All,

I am having a few problems with my radiator system, I have had a new boiler fitted earlier this year and I have also fitted an additional radiator as well as rerouting the pipework to another.

My problem is that one room isn't getting to temperature, I have one radiator which is noticeably cooler than all the others.

The area that is the problem has 4 radiators T off in a close location to each other, probably they all Tee off within a 500mm area of the 22mm main pipe, could this cause one radiator to be bypassed by the main flow and just receiving a trickle from the Flow.

I have tried various things like turning radiators off and balancing the system which has improved things but not solved them, any thoughts?

The system is:-

Combi Boiler "Potterton Titanium 33"
22mm pipework for Flow and Return
15mm Branch pipes to each radiator
underfloor heating system
It has been Flushed
all radiators have been balanced to 1/2 turn on lockshield
15 Radiator system
Mainly all TRV's

[lets have a look]

turn off all the radiators including the bathroom except the cold one and see if it gets hot