You may have read that baseboard hot water heating systems offer many advantages, both technical and aesthetic, over the more common forced air systems. But what exactly are these baseboard systems?
To begin with, they are one of the ways of using hot water to heat the home - one of the so called hydronic heating systems. Hydronic just means that it uses water.
Wall hanging radiators and hydronic radiant floor heat can also use water as the heating medium. They radiate the heat out into the room, either from pipes running under the floor or from hot water filled metal radiators. The water has to be heated in a furnace (that can be powered by gas, coal, oil, wood or electricity) and then pumped around pipes all over the house.
Hot water baseboard heat specifically refers to radiators at baseboard height - this has the advantage of being quite unobtrusive - some people find the wall hanging radiators pretty ugly. There are also residential electric baseboard heaters available, but these are usually less efficient.
For many hot water baseboard heaters combine the best of all worlds - they are efficient, you do not need to rip all the floor up to fit them, and they are not an eyesore.