What's the best central heating boiler?

Central heating differs from local heating in that the heat generation occurs in one place, such as a furnace room in a house or a mechanical room in a large building (which is not necessarily the "central" geometric point). The most common heat source is through combustion of fossil fuel in a furnace or boiler. The resultant heat is then distributed typically by forced air through ductwork, by water circulating through pipes or by steam fed through pipes. Of increasing use, the heat source may be solar powered, in which case the distribution system is normally by water circulation.