Your question is in the Mobile Phone category but no matter.
Presumably you have "bled" the radiator...
It may be that all the early rads are stealing the available heat before the pumped water gets to number 14.
Balancing means progressively and slightly closing the outlet valve (lock shield valve) on each of early rads and opening the lock valve more on the later ones - to even out the heat loss on each.
The circulating pump usually has a speed control - you might turn it up a notch.
The heated water at the boiler has its temperature controlled by the boiler's hot water stat - you might increase the level of this - but not too much else the early radiators may become too hot to touch.
You may also consider having TRVs fitted to each radiator - given that you have 14 of them the chances are you do not need to heat all your rooms equally all the time - i.e. you can run some radiators cooler and have more heat available for the rooms you wish to be warmer.
Good luck...
Peccavi
August 2010