2 radiators cold

[Dsgas]

have a worcester 24 sbi fitted to an unvented system with 12 radiators in a two storey house.got the pump and automatic air vent replaced because pump was making noise and there was black sludge coming out of automatic air vent,this sludge is also present at some joints on service valves.two radiators are also not working,1 upstairs and the other 1 downstairs both oppisite side of the house to the boiler,have tried balancing system but no joy,any help appreciated.

 

[newbie1]

my guess when boiler fitted no powerflush was done prior to fitting so now system has got all the old crap floating around in it hence pump making a noise as its trying to pump sludge not water and your system needs a good powerflush as no amount of balancing will help with a sludged up system

 

[Dsgas]

will give it a go cheers