2 cold rads downstairs

[dave10011]

hi everyone.
got a 3 story house. 8 rads. ecomax 824. had the lounge and diner rads replaced with bigger rads in the summer. noticing that bottom of each of therse rads is cold( about 1/5 of rad from bottom) one pipe going in boiling other pipe out is lukewarm.other rads fine including hallway and kitchen. ive shut off other rads up stairs still no effect. these two rads are at the last on the sysytem. pump on boiler just not able to pump so much??

i need a new boiler anyway in the summer . looking at 30kw more pumping power i guess? thanks

 

[Plumber90]

What size pipes are feeding the radiators and what size are the radiators.

 

[dave10011]

15mm. two rads reaplced were 600mm. replaced with 1200mm. even with upstairs swicthed off the pump should still be able to pump to them so eliminating the pump/balancing as an issue? one pipe in each side is piping hot the other return or flow is cold/lukewarm so circulation issue? thanks

 

[ALCPlumbing]

It won't be a problem with the pump if there's only 8 rads on the system. It's more likely that it needs balancing properly. Anyway I'm pretty sure the pump is exactly the same in an 824 as an 830. The difference is more heat output. I'm sure your boiler would cope if balanced properly but an 830 would give you better performance on the HW side. Have you tried shutting the other radiators down a bit to push the heat to the radiators that are lukewarm.

 

[Elkato531]

Sorry to ask the obvious but are both valves on each of the new rads fully open?

 

[JohnD]

Turn off all the hot radiators.

Do the cold ones now get hot?