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202 CHAPTER 15 1962 Guide And Data Book tern, a detailed study of (1) Gist cost, (2) owning and operat ing cost, (3) space requirements, and (4) effect on total build ing or remodeling costs, should be conducted. Some of the pertinent factors of the major systems will be listed. Indirect Systems The indirect or chilled water system b common in this application particularly on large projects or when the space is part of a larger system, such as an auditorium in an in dustrial plant or a church in an office building. Savings can be made in the total installed equipment, because the space may have a peak load at a different time than the rest of the build ing. In the case of auditoriums, containing an ice rink, the air conditioning compressor may also be a part of the ice making system. Indirect systems usually make use of reciprocating liquid chilling units, hermetic electrical centrifugals, steam turbine driven centrifugals, or absorption liquid chilling units. The choice depends on the availability of steam, high temperature water, or power, and relative costs. Direct Expansion Systems Direct expansion systems employ central station fan and coil units, a reciprocating compressor and air, water, or evaporative condensers. Within the tonnage range of these systems, they are usually the lowest in first and operating cost. Broad industry usage of this type of system makes it the easiest to engineer, install, and maintain The direct ex pansion system b the one normally used in churches. Factory Assembled Self-Contained Units Self-contained or packaged units are finding increasingly greater acceptance in these applications. They have afl the advantage of the field assembled systems and are usually lower in first cost Their compact size b an advantage when airconditioning existing buildings. High salvage value, ease of operation and low maintenance are other advantages. These units are offered in sizes from approximately 2 to 100 tons, mpng water, air, or evaporative, integral or remote con densers. ice or Water Storage Systems In many churches the system used combines the chilled water system with a storage tank for storing cold water or with a commercially available ice storage container. In thb system, a relatively small condensing unit operates continu ously 24 to 48 hours prior to the peak load, to store up the necessary capacity. Thb system had the stated advantage of low operating costs when high demand rates are charged. However, the operating costs of a standard system, nudrmg use of precooling, will be approximately the same or lower, due to the shorter running time. The disadvantages are high first cost, due to the storage tank, extra piping and controls, large space requirements, long recuperation period and opera tional complications. Ice Melting System A system similar to the ice or water storage system is the ice melting system, where capacity b bought in the form of ice. The chilled water, formed from spraying water over the ice, b circulated to an air handling unit for cooling. Very few of these systems are still in operation, due to high operating costs and poor temperature and humidity control. Heal Pump Systems On new construction, particularly in the southern portions of the country, heat pump units are becoming increasingly more popular for these applications. (See Chapter 4, Heat Pump Systems for Air Conditioning.) DESIGN Load Calculations The cooling load b calculated in the normal manner using the information contained in the section on Cooling Load Factors in thb chapter and also Chapter 28 Air-Conditioning Cooling Load in the 1961 Guide Arm Data Book. The cooling load of the sanctuary portion of churches will vary between 0.045 and 0.060 tons per person. The load on the other spaces: educational facilities, fellowship h*H offices, etc., will depend on the usage and other pertinent factors. A simplified estimating method for theaters based on field tests has been presented.1 It applies to the basic movie theater, the auditorium portion and any other section con nected directly to it, but not the manager's office, lobby, restroom areas and projection booths which have their own special and distinct problems. Allowing the excess ventilation air to spill out from the lobby to the street b usually sufficient to cool the lobby and advertise air conditioning to passere-by. In order to use thb method, the following information is re quired : theater location (thus the outdoor design conditions), the seating capacity, the ventilation air (cfm per person) and the desired inside design conditions. Equipment Location The equipment should be located close to existing utilities (water, power, drain and gas) and to the conditioned space, in order to minimize installation cost. However, vibration and noise isolation b also an important consideration in the equipment location *nH design. The inherent noise level of these applications will range from 35 to 40 decibels. Equip ment located on structural members of the buildings should have vibration eliminators and isolation type pipe hangers should be used to prevent vibration transmission to the build ing. Special treatment is also required where piping or duct work passes through partitions or floors. Where short duct work runs are necessary between supply or return grilles and the air Handling units, sound absorbing duct lining, cells or baffles should be used. Air Distribution The air distribution system should be designed to supply the required air quantity without objectionable noise or drafts. Good engineering design b more important than the type of system used. Depending on the space arrangements, ceiling or sidewall distribution, wall registers and windowsill outlets have been successfully used. Fig. 1 shows a typical theater air distribution system. In churches, special treatment b required to provide spot cooling at the altar and pulpit and sometimes in the choir loft. These locations are usually elevated above the congregational seating area, and thus are warmer due to stratification, whereas due to the heavy vestments or robes worn, a lower temperature b required. Noise prevention should be paramount in the design. The foDowing duct design recommendations are based on the usual engineering factors. Main duct velocities of 1500 feet per min and branch or runoff velocities of 1200 feet per min public Building Air Conditioning 203 are recommended for conventional systems Take-off runs should be carefully designed and all square and short radius elbows should be equipped with properly designed turning vanes- Return air grille locations are not critical except that they should not be placed near seated people, nor permit direct transmission of sound from apparatus. Normal loca tions are at the rear of the auditorium, the back of rear pews or in the steps to the altar or stage. In theaters or auditoriums uyd for live shows with orchestral .accompaniment, the proscenium (or pit) should not be used for return air. Return air grille free area velocity should not exceed 600 feet per min. Return air duct velocity of 1200 feet per min is satisfactory. To allow good HtHnwng of the system, dampers and splitters should be installed. Outlet velocity should be selected to give good air quantity and distribution. Control System The control system for these applications should be de signed for the operational and maintenance help available at the project. For instance, in the case of churches, a janitor will probably operate the system, whereas on some larger systems an operating engineer may be employed. The lower the qual ity of the operating personnel, the ampler and more auto matic should be the system. A simple control system will also require less maintenance and service. Church auditoriums can usually be adequately controlled by means of an on-off system, whereas Sunday school rooms or an educational building may require zoning or means of individual room control to take care of changes in population and solar effects. Rma.ll classrooms can usually be controlled by means of limited volume control. The normal control sys tem employed for theaters and auditoriums b face and by pass control. Thb system will give better relative humidity control than on-off control. On larger jobs, it b usual to vary the compressor capacity with the coil load as it changes with outdoor air temperature. Operating cost can be saved by using outdoor air for cooling during the intermediate seasons. Many churches have Sunday school rooms in the basement underneath the church sanctuary. If thb space b not used simultaneously with the church sanctuary, a first cost saving can be made by sizing air handling equipment for each space, but ailing the refrigeration equipment for the larger of the two loads. The refrigeration equipment will operate only for tiie space requiring cooling. Note that in most cases, compres sor capacity control b required to prevent coil frosting when only the email unit b running. When the Sunday school load is small, the refrigeration capacity may be enough to cool these quarters and also precool the sanctuary prior to the service, operating only on return air. SYSTEM OPERATION The operation of the system b dependent entirely on its design. Therefore, detailed instructions for the operating personnel are required. Many of the factors of the system operation have been in the previous sections. Main tenance in many installations had been neglected due to the lack of knowledge and necessary skills on the part of the operating personnel. ECONOMICS The installation cost of the equipment and systems can be estimated in a normal manner. The problem b somewhat simplified by the load estimating methods described here.1 As these methods reduce the load estimating time to a mini mum and allow a general calculation of the tons per seat to be made for a specific geographical area and inside design con dition, the next logical step is to calculate the dollars per seat based on the various types of systems used. These figures will prove useful for checking and budget estimating. PART III--EATING AND AMUSEMENT PLACES Air conditioning of restaurants, cafeterias, bars, ami night chibs presents all of the usual problems encountered in com fort conditioning with the addition of several factors specif ically applying to thb type of application. Some of these are: 1. Extremely variable loads with high peaks occurring in many cases twice a day. 2. High sensible latent heat gain* due to gas, steam, and electric appliances. 3. High concentration of food, body, and tobacco-smoke odors necessitating adequate ventilation with proper exhaust facilities. 4. lwali^ high sensible latent heat gains in night club and dinner club dancing areas. 5. Unbalanced conditions in restaurant area adjacent to kitchens which, although notapart of the conditioned area require attention. 6. Heavy infiltration of outdoor air through doors due to high usage factor during rash hours. SURVEY Hie firat approach to any air conditioning problem b an accurate survey. It b especially important in restaurant ap plications to obtain all the data relating to time and duration of all peak loads caused by people, sunlight, and restaurant equipment. Amusement establishments are often divided into several areas such as a bar, a cocktail room, restaurant and night club; in which case, it b necessary to determine the peak loads in each area since they usually do not occur simul taneously. During the survey, it b advisable in restaurant and cafeteria applications to advise the owner of any possible improve ments that can be made to reduce existing heat gains. Due to the highly concentrated sensible and latent heat loads en countered reductions can frequently be made that more than pay for the initial outlay in reduced cost and operating ex pense of the air conditioning equipment. Items to be con sidered are as follows: 1. If any unhooded or improperly hooded equipment, such as coffee urns, steam tables, toasters, grills, etc., are within the conditioned area, they should, if at all possible, be removed to the kitchen, or efficiently designed hoods should be in^alled 2. A study should be made of printing exhaust fans with the following possibilities in mind: \\rrn i H' 1 \> |.r! } r .