Another cold radiator problem

Hi - not an unusual problem as I ve seen from other postings but am after your collective, expert opinion please.

Double convector radiator in lounge warm(not hot) at top and cold at bottom. TRV open to max and pipe feeding it feels v hot. Have had radiator off and flushed through with little effect - gunk did come out.

All other rads working brilliantly.

We moved into the house 2 years ago and had a lot of work done -including a loft conversion. Could it be that the boiler / pump is not strong enough to cope with the new demands on it. This rad is the furthest away from it?

Have got a service contract with BG and they suggested turning the boiler up to max and switching the HW timer off to 'concentrate feed'..???

Could it be that I need to flush the whole system (surely other rads would be similar?) replace the rad / pump or simply balance the system?

I would suggest you turn all other radiators off bar the one that isn't working correctly. This should therefore prioritse the radiator. It may also clear an air lock if there is one (possibly). If the radiator comes hot you know that the system needs balancing. If it doesn't i would try to pull the rad legs through by putting a half inch drain cock in the rad, if the radiator can accommodate it that is. Let us know!

thanks for your help. I will let you know the outcome