Document 82a24GMprN4E8584bamQXaRyZ

1000 CHAPTER 44 extend to other facilities beyond the equipment being discussed here^it important that only an equitable share of the group's time be charged^ maintenance. Extraordinary repairs are quite often handled by separate maintenance divisions and the expense charged back to air conditioning, heating, and ventilating. In other cases, all maintenance is handled by outside service firms and the cost considered as maintenance. These costs vary to sucli an extent that the type and cost of the purchased equipment may deter mine the amount of maintenance necessary. Therefore, any forecasts maintenance costs should include consideration of the equipment as'a part of the engineering study. The charges should be based upon the entire period under study rather than the early years of operation when repairs may be expected to be at a minimum. The accounting practices of the owner and the rules of the Bureau 0/ Internal Revenue affect the charges for major overhauling or complete re placement which may restore the capital value of certain equipment items. In these cases the expenditure may not necessarily be charged as mainte nance but will become a fixed charge spread over the remaining years of Table 4. Approximate Maintenance Cost fob Large Aib Conditioning Installations, Using High Quality Equipment Dollars peb(Ton)(Ybas) 0.96 0.40 1.36 0.24 1.19 equipment life. Table No. 4 gives some approximate costs for maintaining . large air conditioning installations using high quality equipment. LABOR FOR OPERATION In some cases with the installation of automatic equipment, operating labor may be non-existent, but where such labor is required, the cost is readily calculated. Where operators are required, the expense is often considered maintenance, but since they may have other functions which are not properly charged to operation of the air conditioning, heating, or ventilating installations the charges should be properly allocated. The cost of experienced and competent operators is well justified in medium and larger plants by economies that can be achieved in maintenance and energy costs. ENERGY AND WATER COSTS Energy costs include the costs for power, water, steam, coal, oil, etc. consumed to operate the system. From the selected equipment and type of installation, it is possible to segregate the relatively constant power loads and the total brake horse power. Annual power cost can then be figured from the following formula: 0.746(bhp)RR annual power coat = -------------------- (1) t Owning and Operating Costs 1001 bhp = brake horsepower. H = annual operating hours. R - power rate, dollars per kwhr. , = motor efficiency (decimal). In using Equation 1 it must be pointed out that the electric rate, R must reflect the proper combination of energy and demand rates. These vary widely between the utility companies, and sometimes the rate struc ture is such that it is largely the demand charge which determines the proper value of R to use in Equation 1. Table 5. Equivalent Full Load Operating Hours of Refrigeration Equipment Used for Summer Cooling May 15 to Oct. 15* Application HbOpen FOB Atlanta Business Boston Chicago Detroit Los Angeles New Orleans Department Stores............................ Specialty Shops (5 4 10)............ Theaters--Continuous........... Theaters-- Neighborhood............. 1280 940 600 940 1290 2100 1090 1500 900 1010 840 1630 440 870 970 1510 800 1010 640 650 720 720 560 610 610 950 1060 1060 330 330 560 620 621) 535 620 621) 820 930 930 530 590 590 700 750 750 420 450 450 680 1080 580 890 980 1790 310 470 580 900 570 1060 850 1690 560 860 720 1080 430 650 Application Hr Open fob Business Barber Shoos____ Department Stores . Drug Stores___ Funeral Parlors....... Offices... ................................ Restaurant (Short Hour). Specialty Shops (5 & 10).............. 1 heaters--Continuous.. . . 'Hearers-Neighborhood............. 1280 940 940 1290 2100 1500 900 New York 830 700 370 710 760 1170 670 850 500 Phila delphia Oklahoma City St. Louis 7211 740 800 1210 son 870 *>20 840 1650 440 9S0 1530 810 1020 770 830 1300 720 910 550 Wash ington D.C. 1530 810 1400 750 950 . Modern Air Conditioning, Heating and Ventilating, by W. H. Carrier, R. E. Cherne and W. A. Grant <FUm PniiirHng Carp. 1940, p. 73). Operating Refrigerating Equipment , ^ an air conditioning system the refrigerating equipment is usually he largest power consuming item to be considered. Also, the prediction w operating COst is more difficult because the power required for summer oohng is affected by many factors of a variable nature. Table 5 gives the equivalent full load operating hours of refrigerating quipment used for summer cooling for the period of May 15th to Octo- r loth. This table was calculated from the following equation: inhere ff. = m(b -+- cj) (2) 6 - equivalent full load operating hours of refrigeration equipment used for summer cooling during period May 15 to October 15.