Document e7ymXpjeQQxDMv4Ngb3JVZ8qp

1076 CHAPTER 43 1957 Guide extend to other facilities beyond the equipment being discussed here, it is important that only an equitable share of the group's time be charged to 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 consider ably with factors such as the type of system and the proficiency of the installing and servicing organization. Therefore, any forecast of main tenance 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. Various estimates of maintenance costs vary from 5 percent to 10 percent of the installation cost. Table 4 is based upon an average of 7\ percent for about a 75-ton installation. This probably would apply to most in stallations using high quality equipment. The maintenance cost must be Table 4. Approximate Maintenance Cost fob Labge Aib Conditioning Installations, Using High Quality Equipment* Dollars per (Ton) (Year) Total.......................................................................................................... * Estimated for 1955. 1.07 0.40 0.11 " 0.45 1.50 0.26 1.38 5.17 modified for size of job and quality of equipment . With lower cost equip ment, higher maintenance costs can be expected. The accounting practices of the owner and the rules of the Bureau of 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 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. Owning and Operating Costs 1077 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)flR annual power cost v (1) Table 5. Equivalent Full Load Opebating Hours of Refbigebation Equipment Used fob Summeb Cooling May 15 to Oct. 15* Application Hr Open fob Atlanta Business Boston Chicago Detroit Los Angeles Nsw Orleans Barber Shops.................................. Department Stores........................ Drug Stores.................................... Funeral Parlors.............................. Offices............................................... Restaurant (Short Hour)............ Restaurant (Long Hour)............. Specialty Shops (5 A 10)............ Theaters--Continuous.................. Theaters--Neighborhood............. 1280 940 2100 600 940 1290 2100 1090 1500 900 1010 > 650840 560 1630 950 440 300 870 660 970 535 1510 820 800 530 1010 700 640 420 720 610 1060 330 620 620 930 . 590 750 450 720 " 610 1060 330 620 620 030 590 750 450 680 580 980 310 680 670 850 ! 560 720 430 1080 890 1790 470 900 1060 1690 860 1080 . 660 . Application Barber Shops..................... Department Stores........... Drug Stores........... ......... Funeral Parlors................. Offices................................. Restaurant (Short Hour). Restaurant (Long Hour). Specialty Shops (5 A 10). Theaters--Continuous.... Thearera--Neighborhood. Hr Open FOR Business 1280 940 2100 600 940 1290 2100 1090 1500 900 New York 830 700 1280 370 710 760 1170 670 850 500 Phila Oklahoma delphia Cm ` 860 720 1330 380 740 800 1210 690 870 520 1020 840 1650 440 880 980 1530 810 1020 650 St. Louis 890. . 750 1420 400 770 830 1300 720 910 550 Wash INOTON. . D.C. 940. 780 1530 410 810 880 : 1400 750 950 580 * Modem Air Conditioning, Heating and Ventilating, by W. H. Carrier, R. E. Cherne and W. A. Grant Pitman Publishing Corp. 1940, p. 73). where bhp = brake horsepower. B = annual operating hours. R = power rate, dollars per kwhr. i? = 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. Operating Refrigerating Equipment In an air conditioning system the refrigerating equipment is usually the largest power consuming item to be considered. Also,' the prediction