CHAPTER 14 AIR CONDITIONING AND REFRIGERATION

A Utilitiesman is expected to know technical informaiton about the air conditioning of buildings and the refrigeration of perishable products. This chapter covers the aspects of selecting and installing air-conditioning and refrigeration equipment. The individual components required in an airconditioning system and a refrigeration system are also discussed. Finally, the fundamental electrical knowledge you actually need to install, maintain, and repair air-conditioning and refrigeration equipment is discussed.

SELECTION AND INSTALLATION OF AIR-CONDITIONING SYSTEMS

There are two types of air-conditioning systems that must be considered before selection and installation of equipment. The first system discussed is forced air. Then, in turn, the hot and chilled water system is discussed.

FORCED AIR

Forced air units are used when the areas to be air-conditioned are close to each other, are being used for similar purposes, or have the same humidity and comfort zone requirements. A few examples are office spaces, single-dwelling homes, and single-purpose shops. Some characteristics of the system that must be taken into consideration during the planning phase are the following: to keep units centrally located, to ensure return air is drawn from the area being cooled, and to ensure that one thermostat controls the system. See figure 14-1 for two examples of a forced air unit with accompanying ductwork.

HOT AND CHILLED WATER

Hot and chilled water units should be used when the areas to be air-conditioned are dispersed, have a wide range of different uses, or have different humidity and comfort zone requirements. Some examples are a barracks, a galley, or a hospital. Some characteristics of these air-conditioning units that must be taken into consideration regarding this system are location (mechanical room), use or nonuse of return air (hospital operating room), humidity and temperature controls, individual room temperature requirements, and amount of installation space for piping and ductwork. See figure 14-2 for a typical piping diagram of a year-round air-conditioning system.

If you are involved in designing an airconditioning system or desire more information, refer to NAVFAC DM 3.3, Heating Ventilating Air-Conditioning and Dehumidifying Systems.

HEAT LOAD CALCULATIONS AND AIR MOVEMENT

Once the type of air-conditioning system has been chosen, the next step is to figure out its appropriate size. There are two primary factors that must be considered. The first factor is heat load calculation. Humidity comfort temperature, and psychometrics are the three primary considerations necessary for calculating heat load. The second factor is air movement. Velocity, pressure, and drafts are the three main factors that are important when you are designing and planning the size

Figure 14-1.-Arrangements for package-type air-conditioning units and air ducts.

Figure 14-2.-Typical piping connections for a year-round air-conditioning system. 14-2

of an installation. Figure 14-3 shows the relationship between humidity, temperature and air movement.

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