RADIATORS ARE COLD ON BOTTOM I HAVE TAKEN RADS OFF AND FLUSHED THROUGH WATER CLEAR HAVE ADDED FERNOX CLEANER STILL NO LUCK KEEP BEING TOLD ITS SLUDGE BUT I HAVE MY DOUBTS I AM JUST WONDERING IF IT IS BECAUSE IT IS A ONE PIPE SYSTEM ALTHOUGH IM TOLD IT WOULD JUST TAKE LONGER TO HEAT UP BUT WHEN HOT WOULD WORK OK. I HAVE A WORCESTER COMBI SYSTEM WITH 9 RADS. ABOUT 4 ARE COLD OR WARM HAVE SPENT A FORTUNE ON CALL OUTS STILL NO JOY CAN ANY ONE HELP REGARDS KATE[/quote]
A usual cause of cold radiators especially at the bottom of the radiator , is usually down to trapped air.
you'l need an air tap key (Radiatior key) to bleed the radiator therefore releasing the air and drawing the hot water through your radiatior.
Trapped air usually causes the radiators to be cold at the top, not the bottom. Usually cold at the bottom is due to sludge or lack of flow through the system. normally this would be rectified by flushing or balancing the system.
However with a single pipe system this is not so straightforward. My advice would be upgrade the system to a 2 pipe system, have a powerflush and put some of your expensive call out charges to better use.
You should have really been advised to change the system when the new boiler was installed.