Cold downstairs radiator problem

[MickBrown]

Last winter everything working fine. Switch on this winter and 2 downstairs radiators do not work, others downstairs and those upstairs fine. Turn off all radiators except one cold one, it heats up okay. Turn back on other radiators and it goes cold again. Do same for other cold radiator and this one only gets luke warm, however it stays luke warm when others turned back on. Eon, who have maintenance contract, says it needs a power flush. Any thoughts please.

 

[Simon F]

my first thoughts were trapped air, but you would have shifted that by closing the other rads to get the problem ones working.
possibly needs flushing, but the rads do work when others are closed,
suggests a balancing issue.
has anything been done to others radiator to have affected the system balance?
do Eon want to do the flush for free or charge??

 

[galaxy_plumbing]

sounds like balance issue to me, however why would that show now and not before, unless somebody was playing with valves of course

 

[SafeGasInstall]

Or don't forget that pump could
be tired

 

[Simon F]

Or don't forget that pump could
be tired

very true, or could also be motor on 3 port not fully opening.
both could give limited flow to index circuit.

 

[SafeGasInstall]

time for to call the plumber