2 rads not working

[marsaday]

I have a big system on a house i rent out - 14 rads.

2 rads never get warm and the valves are fully open (the ones which change the amount of water into the rad.

I think it is something to do with the size of the house as it is very big over 4 stories and i had to fit an extra pump on the system when installed.

any ideas ?

 

[someonelse]

Pump not turned up to max setting.
Pump not powerful enough.
Boiler too small.
Rad valves at both ends fully open?
Pipe blocked.
Air in rads.
Sludge in rads.

Assume these are the rads furthest from boiler at top of house?[/u]

 

[marsaday]

i will check the pump turned to max.

it cannot be the pump is not powerful enough because i have fitted an extra one, so there are 2 on there.

the rads not working are in the front room (ground floor) and the bed directly above this room on first floor.

The boiler is in the basement.

i have bleed the rads and no air.

rad valves fully opened.