Document JrO5Exv6omM5zyNeoJ7nRkwar

HEATING VENTILATING AIR CONDITIONING GUIDE 1943 Types -of Units Unit air conditioners fall into two general classifications, depending on the location of the refrigeration source. Those units having the con densing unit completely enclosed in the same cabinet as the evaporator are known as self-contained types, while those units having the condensing unit remotely located from the evaporator and requiring piping of refrigerant from the condensing unit to the evaporator and return are known as remote types. Self-cpntained units are further divided into two groups in accordance with their condensing mediums, being either air-cooled or water-cooled. Evaporative cooled types are included in :this latter class. The air-cooled types are small in capacity, ranging from 34 to 134 hp. Their principal application is for conditioning such spaces as hotel rooms, offices and residential living quarters. A duct connection between the CONDENSER-AIR CHAPTER 23. UNIT AIR CONDITIONERS, UNIT AIR COOLERS, ATTIC FANS condensate from the cooling coil is sprayed over the condenser surface and vaporized, thus eliminating the need for .drain connections. A simple tampering arrangement is generally provided for exhausting'some air from the room, in addition to introducing outside air and recirculating required amounts of air. It is possible to remove the equipment for winter storage or utilize the ventilating features for winter operation. Water or evaporative-cooled units start at 1 hp in size and may be as large as 30 hp. Condensers requiring water use either city water, well water or recirculating water from a cooling tower. Evaporative con densers are seldom used on units under 5 hp. The heat generated by the compression of refrigerant gases and that given off by the electric motor is removed from the compressor compart- Fig. 1. Self-Contained Air-Cooled Unit Air Conditioner unit and an outside window or ventilated air shaft is required to permit disposal of the heat extracted from the conditioned area. The. unit may stand in front of the window or be mounted on the window sill. Various styles and types of windows are encountered which increase the difficulty of making the window connections. The evaporation of condensate on the condenser coils, as a means of disposing of this moisture, tends to increase the condensing capacity and reduce the operating head pressure. Some units add supplementary water so that increased capacity may be obtained from constantly wetted condenser coil surface. Connections.to an electrical outlet may be by means of a conventional cord and plug or a permanent electrical connection, depending on local code rulings per taining to the installation of small motors; The exterior finish of the unit in metal, wood or fabric is decorated to harmonize with office or bed room furnishings. A unit of the air-cooled condenser type for floor mounting is shown in Fig. 1. Of the two fans shown, the lower one acts as condenser air fan, and in some units this fan is arranged with slingers for discharging con densate on the condenser coil while the upper fan discharges air into .the conditioned area. A feature of the design shown in Fig. 1 is that the 444 Fig. 2. Self-Contained Water-Cooled Air Conditioner ment in four ways: by the use of a water coil in the compressor compart ment; by means of utilizing the cold suction gases; by drawing part of the return air through the compressor compartment and finally by. circulating room air through the compressor compartment by, means of a fan attached to the motor shaft. The smaller water-cooled units have somewhat the same application as the air-cooled units. Water and drain facilities must be available and, although window connections are not required for heat disposal, it is desirable to have an outside air connection for ventilation purposes. Electrical wiring is generally permanently connected. Up to 734 or 10 hp in size the units are usually styled for locating directly in the conditioned area. Above this size the tendency is to locate the equipment adjacent to the conditioned area, with supply and return duct connections. Compressor compartment heat is removed by the same methods, described previously. On water units of the vertical type of 5 hp and under, use is made of ' 445