If you are wondering why one room in your house feels so much cooler than others when your central heating is on then this may help.
Usually the coolest radiator will be the one that is on the lowest floor and furthest from the boiler so if the boiler is at the back of the house it may well be your front living room.
What needs to happen is that the radiators need to be balanced which you can quite probably do yourself. If you have a small cap at one end of the radiator, under this cap there is probably a small valve which can be adjusted by use of a pair of pliers or a small wrench. By shutting off each of these valves in turn (clockwise turns) and then opening each one up again by half a turn you can ensure that every radiator is getting the same amount of hot water. By adjusting the valve in the coolest room by opening it another half turn or more you can then control which rooms are getting the most hot water to their radiators.