Guys Need a bit of assistance, i have 1 radiator upstairs which doesn't get piping hot like the rest. It should be free of sludge as i recently replaced it along with new TRV and lock shield etc. The TRV pin is fine, lockshield is fully open. all rads are balanced and still same. I did turn off all rads from lock shield apart from this 1 and it did get hot. But didn't check return pipe on the Rad to see if that was hot too. I think its a case of either a kink in the pipe work from the onset or sludge in the return pipe on that rad. How can i eliminate what it is? Also if it sludge in that pipe, how can i clean it out without having to do a power flush ? Its a 10mm pipe by looks of it.