Lined Radiators?

[thechasman]

Ok to answer the original question. if no air can get in then corrosion, sludge etc is non existent, other than residual currents, earth faults etc, and dissimilar metals. O and most fluxes if not flushed after install.

I don't suppose you have a one pipe system by any chance, as this would make any powerflush pointless unless every rad is removed and flushed individually, by the same reasoning it could mean you have the wrong TRVs fitted.

Is there a way to tell without tearing the floor up?