One Radiator not getting hot

[brewer36]

Hi Guys
Can anyone please help me. We have had a new boiler fitted and radiator thermostatic valves. The plumber drained the system and flushed it out before fitting. Everything worked for a couple of weeks then we noticed that the radiator in the hall that dosesn't have a thermostatic valve on it is not getting hot. The boiler a Worchester Greenstar cut out a few times so the boiler people came and checked it saying it worked ok. British gas came and put a new pump in and said that the system needed a Powerflush (?). The plumber says its ok and doesn't need it. Is there anyway I can check if the system is blocked and if it is unblock it. I'm a bit stuck as nobody wnats to help me out.

Thanks

 

[gas4you]

Have you tried the basics;

hot water off, heating on, pump on full, close bypass if fitted, turn off all rads except hall, does it now get hot? bled hall rad, checked hall rad valves are both fully open?

Is the water black, rusty or sludgey? Did you see your plumber get the powerflush machine out and flush it?