Requirements for Heating System
In order for a system of heating to meet the demands of hygiene there must be a minimum cost of production and absence of impurities produced in the process of heat; the heat must be equitably distributed over the house; the temperature must be kept even, thus insuring continuous heating; and there must be a proper degree of humidity. There must also be freedom from explosions and danger from fire.
There are three methods of heating; radiation, conduction and convection. There are two systems by which these methods are used: they are local and central. In local systems the heat is produced in the room by combustion or burning of fuel in grates and stoves.
In central heating the heat is produced at a central place outside of the rooms and conveyed to them by hot air, hot water or steam.
Even though these three methods of heating are usually given, it is difficult to draw hard and fast lines of demarcation between the different methods, for, as a matter of fact, they overlap to quite an extent. The element of radiation is involved in both conduction and convection.