Changing like for almost like

[onlyagirl]

The double radiator in my lounge (600mm/970mm) is just not heating the room adequately; feels like just background warmth after the combi boiler has been churning away for hours, obviously costing me a lot of money. The lounge is 11ft by 12 ft.
I have decided to find out about installing a triple panel radiator in place of the double panel. There is no room in the lounge for a separate additional radiator.
The question is: would a triple panel convector radiator make enough of a difference, and would the installation be fairly straightforward? The combi boiler was installed in 2012 and it runs 7 other average sized radiators; only one other of them is a double. The boiler manual says: heat output condensing 25.7 CH, heat output 28.1 DHW.
The plumber is having a look tomorrow and I just want to get some knowledge beforehand.

 

[PrenticeBoyofDerry]

To heat a room that is approx 4mx4m with a standard height of 2.4m, taking consideration of double glazed windows and possible external walls, is going to require about 5500 BTUs, so about a 1.6kW radiator is required and I would expect that from a 900X600 T22 double panelled radiator. I have not come across tripe panels at this size. I would expect about a 25% increase of output from a T22 to a T33. Whether that is sufficient for you is impossible to say. I would personal be looking checking the radiator is producing it's design output, you may need to bleed or balance the system, then look at decreasing your heat-loss values.