Air heaters
Introduction
Hot water heating. This is the name given to heating systems that use water as a heat transfer between the generation system, commonly a boiler, and the emitters or terminal elements located in the premises to be heated. The hot water generated is transported through a network of pipes.
The hot water heating system is undoubtedly the most widespread in heating installations. The increase in the application of air conditioning systems in all types of buildings makes hot air heating systems increasingly common.
Historical evolution
Towards the end of the century, James Watt, known for his steam engine, installed heating in his Manchester factory, with the steam left over from the industrial process. Many other similar installations, with greater or lesser success, are installed around the world. They are the first heating installations with distribution through pipes.[1] In 1880, some Companies distributed heating steam in several North American cities (district heating). In Europe, the first district heating was built in Dresden in 1900.
But steam is dangerous and represents too many complications to be applied to domestic heating, so around 1895 the first boiler made up of loose elements appears, built by the engineer Strebel.[2] These double-walled "stoves" can send hot water, taking advantage of the thermosyphon effect to "Radiator (heating)" radiators distributed throughout the house. Thermosiphon installations require careful execution. With a thick and high outlet pipe, a good drive differential pressure is obtained,[3] but then the slope of the fall towards the radiators must be scrupulously maintained and air pockets along the route must be avoided. The introduction of the circulation pump, at the beginning of the century, made it possible to considerably reduce the section of the pipes, facilitated the layout of the distribution and increased the performance of the facilities.
From that moment on, the development of heating has been continuous. The appearance of elements such as: the closed expansion vessel, the regulation and control systems, the diversity of materials: steel, copper, aluminum, plastic, etc., added to the energy offer; liquid and gaseous fuels, electricity, alternative energies (solar, geothermal, biomass) together with the diversity of machines and devices to transform these energies into heat and to transmit this heat to the environment, make it impossible to collect all this technology under a single heading.