Document byN98a95Nz9X8k14rKO2QKj7Z

HEATING VENTfLATING AIR CONDITIONING CUIDE 1940 19. Make all valves and controls convenient and accessible, either direct or through remote control. It is only human nature to delay and avoid doing that which is incon venient. 20. Keep a daily record consistently, based on weather requirements, and watch it every day. 21. Control the heat supplied to water tanks located on or above the roof. Such tanks require heat to prevent freezing. No heat is required when the temperature in the tank is above 32 F. 22. Investigate every complaint of no heat by tenants; find the cause and correct it. Do not overheat an entire building to correct a local condition in one room. AUTOMATIC TEMPERATURE CONTROL As stated in Chapter 38, Automatic Control, properly applied to heating, ventilating and air conditioning systems makes possible.the maintenance of desired conditions with maximum operating economy. In addition to the large possibilities for economy, the use of adequate temperature control provides more healthful, comfortable, and efficient working conditions in the buildings because through its use the building is uniformly heated with correct temperatures and drafts, from open windows and overheating are eliminated. . There are many types of temperature control available, each adaptable to a particular,type-of building, but all require uniform distribution of steam and proper venting. Before the installation of any type of modern temperature control equipment, it is necessary to see that the heating system is put in good operating condition. In general, the heating system in a building is not given the attention that other mechanical equipment is given because if will continue to function, after a fashion, even though changes in piping,, location of radiation, settlement of piping, and the normal wear and tear, or other changes have taken place. Through all this depreciation of the system, it becomes more and more costly to operate and parts of the building have to be greatly overheated in order tojjrevent underheating in a small section of the building. Vents, traps, vacuum :pumps, and valves should be given a careful inspection and replaced or repaired if required. The piping should be of adequate size and graded properly. The return piping should have a careful inspection, and any pockets or lifts removed and properly vented. These, inspections and repairs are not costly and prevent a much, greater outlay in future years. In most cities district heating companies will be willing to make a survey of heating systems and offer recommendations-as to operation and changes in piping layout. The selection of control equipment depends upon the type and size of building and the degree of saving possible. v Chapter 44 WATER SUPPLY PIPING AND WATER HEATING Maximum Possible Flow, Maximum Probable Flow, Average . Probable Flow, Factor of Usage,. Kind of Pipe Used, Sizing of Risers, Sizing of Mains, Sizing of Systems, Hot Water Supply, Hot Water Heating, Hot Water Storage, Swimming Pool Heat ing Requirements DOMESTIC water supply systems present the engineer with a design problem that requires combining the somewhat empirical rules and formulae in use with the more or less'exact hydraulic principles involved. Unlike heating and ventilating layouts, there are practically no definite data for estimating the quantity of water likely to be consumed or the probable rate of water flow at any particular moment. Metered results in one building often show two or three times the metered amount in another building of the same size and with the same type.of tenants. In hotels, one riser will often have an almost constant flow that may never be reached by another at peak load. In office buildings, the women's toilets show a far greater daily consumption than those of the men, yet at no time will they approach the hourly consump tion of the men's toilet during the first hour of the day. This condition has led to..a multiplicity of rules of practice which vary as much as the data used HP All must of necessity be based on an assumed rate of con sumption and oh an assumed probability of simultaneous use, and while the formulae employed may have been derived on sound technical basis the assumptions are often in error. To arrive at a safe standard, the approximate rate of flow of each fixture to be supplied must be known and the probable number of fixtures in use at any one time must be assumed. Obviously, the maximum number of fixtures assumed to be in use must be taken at the peak of demand and the lines must be made adequate to supply such a peak regardless of the riser or branch on which the demand may occur. This means that all water piping under the usual-conditions will be over-sized. In tall buildings it is customary to divide the water supply systems, both hot and cold, into sections of 10 to 20 stories. Such zoning1 or `It is impractical to attempt to size piping so as to produce the proper pressure on fixtures at different levels by employing friction, owing to the fact that this friction will bebuilt up to the amount desired only in times of maximum demand and at all other times the friction will.be only a fraction of the maximum friction so that the fixtures by this method are subjected to a varying pressure on the water supply line. A much more practical method is to throttle the flow at the fixture, or to use flow regulators, so that the quantity of water delivered will approximate the fixture demands and so that this is accomplished without splashing or noise. 741