9.2.- HEATING, VENTILATION, AIR CONDITIONING AND HOT WATER

Under normal conditions, the air has a mass content of around 23% oxygen, 76% nitrogen and 1% gases and vapors. Among the gases and vapors the most important is water vapor. Although its proportion is very small, it is very importance in the rate of evaporation of wet surfaces and materials.

The air conditioning and ventilation systems modify air humidity and other parameters, such as temperature and pressure.

As the air parameters are modified, water heating systems are used to obtain specific conditions.

In the everyday life, water can be heated for sanitation purposes (bathrooms, showers) and for other cleaning purposes or for heating. According to its later use, the water is conditioned with a heating system.

Sanitary water can be prepared in two ways:

• By storage: hot water is stored in a tank for the intended uses.
• By instantaneous heating: water flows through a coil heated directly by a flame or heat exchanger.

A heating system raises or maintains the air temperature. It consists of three parts:

• A heat generation system: it can be a fuel boiler, a system operated by heating elements or another system.
• A distribution system: pipes through which hot water or air flows.
• An emission system: radiators, grilles, specific supply elements.

Any of the water heating methods, regardless of the use, must be evaluated, since the energy efficiency variability is very large.