Thee_Psycho wrote:

snip

Think its looking like I will have
to drain the whole system to replace the radiator and valve, but what is a
header tank? I have my boiler in the kitchen, a hot water tank in the
airing
cupboard and a cold water tank in the loft. Or is my Cold water tank split
in to two, wither seperate feeds for the heating and ho****er. I haven't
paid much attention to it, since moving in. Sorry for the lack of detail!


The header tank provides feed/expansion for the primary (radiator circuit).
You could possibly have a primatic hot water cistern, where the primary &
secondary (hot water) circuits are separated by air pressure. Because of
the risk of contamination, you can't use any chemicals with this type of
system. 'Primatic' is a trade name of IMI - have a look to see if the
cistern is marked.

Terry D