Old thread but i just want to send a quick update.

It appears the main reason why my rads were not getting hot was an issue with trvs.

It appears that when there were open at 20-30 they were not getting a flow. Im not sure if its a fault with valves or hr92 design issue but i have unscrewed all hr92 about 2mm. So when they are open at low flow the vavle is open probably in half which makes a flow much better.

I have also set them at full stroke but dont think it actually matters