Some radiators hot, some are cold?

i'll have to agree with SBR plumbing. There seems to be sludge build up. You can add sentinel X300 sludge buster to system . Run it for the duration indicated on the instructions, no more. As it can eat through some old pipework if system is extremely old.. Flush all evidence out from system then add sentinel x100 inhibitor, when satisfied. As SBR said, you may need the system balanced too.

lee S. Wales
January 2007

SYSTEM IN NEED OF FLUSHING AND THEN RE BALANCING

SBRPLUMBING
February 2005

You may recall that hot water output of the heating system of the home go to the radiators and completes its circuit and turns back to the combi. If turn-back filter is closed by dirty water, then the amount of hot water is limited. Consequently some radiators are hot and some are cold. Remedy is to clean that filter.

ali dinc
December 2004

sounds like you have got air in rads you need to bleed them

helzender
December 2004