Document 5bErwm1z6zp2Y0LV0aa6vNZ35

550 CHAPTER 25 1950 Guide MODIFICATIONS OF REMOTE UNITS Features of various modifications of remote air conditioners are given' in the following paragraphs.' Spray Type Unit Fig. 4 shows a spray type unit used by designers who prefer air washing and coil wetting features. These units are equipped with a pump that sprays water or brine over the coils. Due to the direct mixing of the condensate and the spray, provision must be made for overflow in summer and replacement of water evaporated in "winter. Dehumidifying Units In a further modification of spray type units, absorbent, brine-solutions such as lithium chloride are used to remove moisture from the. air. As explained in Chapter 37, the latent heat of the moisture removed , is changed to sensible heat, so that coils must be used as after-coolers to obtain the right dry-bulb temperatures. Factory produced unite are. also available for use with solid adsorbents such as silica gel. Remote Room Units For individual rooms, with cooling load requirements of 5 to 1 tons, remote units are available in attractive casings for installation within the room. A suspended type is shown in Fig.. 3 and a floor type, such as is usually installed in place of an existing radiator,, is shown in Fig.. 5. Furnished with chilled water from a central plant, these unite offer a satisfactory method of conditioning existing offices, hotel, and apartment rooms.- These units may be obtained with filters and outside air con nections, but for most satisfactory application are used as supplements to central systems that supply properly conditioned and filtered air to the areas; served. Induction type unite, using primary conditioned air under pressure to induce local circulation, are described, in Chapter-29. ' -.t Self-Contained Units ' . r . A typical large' self-contained unit is shown in Fig. 6. It is essentially; a remote vertical type conditioner mounted on top of a sound insulated enclosure containing the condensing unit. Air distribution is obtained by means of grilles mounted in the discharge plenum, when the unit is locatedin the conditioned area. Duct distribution of conditioned air can be obtained by removing the plenum, connecting directly to the blower dis charge, and safing the top of;the unit. The heat generated' by the compression of refrigerant gases andr that given off by the electric motor are removed from the compressor compart ment in four ways: by the use of a water coil in the compressor compart ment ; by 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 7, 10,-and 15 ton. self-contained units usually have horizontal type conditioners. . The condensing unit enclosures are. not- completely sound insulated, since they are not usually, installed in the conditioned area. Most unite can be divided into two or three sections for ease of UnitAir-Conditioners and Unit Air Coolers 551 handling and-installation..': Although most large;self-contained-units have water-cooled- condensers, the 7, 10, and 15 ton units can be'Obtained-for operation with evaporative condensers. Self-Contained Room Cooling Units Small self-contained units can be obtained -with water-cooled conden sers, but they are generally air cooled. The air-cooled types are small in capacity, ranging from f to lhp: Their principal application is for conditioning such spaces as hotel rooms, offices and: residential living quarters. A duct connection between the unit and an. outside window or ventilated air shaft is required, to permit \. , / Fiq. 6. Self-Contained . -.. Wateb-Cooled Aib - CONDITIONEB " . disposshof the-heat extracted from the conditioned: area. - The unit, may stand in front of, the window or be mounted on the window sfil. .. .Various styles and types , of windows encountered tend to increase the difficulty of making the window connections. The evaporation ;of condensate on the. condenser coils, as a means of disposing of. moisture, will tend 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 made through a conventional cord and plug or a. permanent. eleCtncaT connection, depending on local'code, rulings .per tainingto the installation of small motors. The' ektferiof finish Of the unit in metal, wood or fabric, is decorated to harmonize with office or bedroom" furnishings. '- ' '' . . A" unit of. the air-cooled"condenser type for-floor'mounting is`shown .in" Fig. 7; Of the two fans. shown," the lower one acts as" condenser ;air'fan, and~in:s6me uhite`this'fan"`is arranged with'sUnjgdi3:fripfllSgHft-gmg*c'6ii; densate on the condenser, coil, while the upper fan-discharges air' into the conditioned area. A feature of the design shown in Fig. 7 is that the