by htg engineer »
Sun Sep 14, 2008 10:24 am
Check both valves are open, try turning off all working radiators to see if problem radiators work. If they do work this rules out faulty valves, blockages etc.
Then try balancing the system, open all wheelhead valves but only open lockshield valves a few turns.
If there's no blockages and it has all worked well before I would take a look at the pump, maybe it's not strong enough with age to cope with all the radiators. If not already - turn up to spedd III, if already on that setting, or still no luck - replacing the pump would probably solve your problems.
htg