If you follow the free lessons at http://www.hydronic.net you will see the procedure for determining the amount of heating element to install in each room. This procedure involves some elementary math. While it is not difficult to use the procedure, it involves some attention to detail and math that is not enjoyable to people who ‘work with their hands,’ so many just guess at the amount of radiaton to put in each room.
There are ways to install any amount of radiation without calculation, going ‘wall-to-wall’ with baseboard covering all available outside wall, then using non-electric zone valves in each room to control the temperature satisfactorily,; however these add cost to the installation.
You are, most likely, a victim of a guesstimator.