Working out Boiler capacity/extending central heating

[willougs]

Hi all.

Probably not a simple answer, but I was wondering if someone could please explain how to work out if my boiler is capable of running bigger/more radiators? I currently have a Gloworm Ultimate 50FF boiler with the following mismatch of radiators:

(all measurements in cm, all radiators are single)
2x 60x40
3x 46x40
1x 60x50
1x 60x60
1x 46x120
1x 60x90
1x 46x50
1x 46x60
1x 46x90
1x 46x80

The reason for wanting to extend is that fact that our hallway (where the thermostat is placed) never gets to a decent temperature. Anything set above 18 degrees approx the central heating never switches off and the hallway is always cold. The hallway is a fair size (5ft x 15ft odd plus the stairs etc) and is being serviced by a small 60x40cm radiator.

Can I replace the radiator with a bigger/double one and not over stretch the boiler? Is the boiler already overstretched?

Many thanks in advance!

 

[ChrisR]

Must be getting close. You'll have to go through a list and add them up. COnvector fins add about a third to a single panel, which you'll need for the sums.