Document 6b78zdV3X1w0R3pr52XNrO14R

American Society of Heating and Ventilating Engineers Guide, 1932 coal having a calorific value of 12,500 Btu per pound is fired, arid the over-all heating efficiency is assumed to be 60 per cent, how many tons of coal will be required for a normal heating season, neglecting other heat sources, and any loss of heat through open windows? Solution. Since there are no partitions in this building, the entire heat loss is con sidered. The average outside temperature during the heating season (k) is 41.9 F (see Table 3, Chapter 2); t = 60 F; N = 5040; H = 500,000; (t -- O = 66 F; C = 12,500; E = 0.60. Substituting these values in Equation 1 and dividing by 2000 to change to tons: 500,000 X 18.1 X 5040 66 X 12,500 X 0.60 X 2000 = 46 tons of coal Inasmuch as the building will be heated to 50 F at night, the average inside tempera ture (at the breathing line) will be 55 F, and the percentage saving will be 4f"9 = 0.276 or 27.6 per cent. The net fuel consumption will therefore be 46 -- 0.276 X 46 or 33.3 tons. Other Factors There are many factors which would be likely to affect the theoretical fuel requirements of a building such as the opening of windows, abnormal inside temperatures, other heat sources, sun effect, wind, rain, etc. In many cases it is difficult accurately to evaluate these factors, particularly in the case of open windows and the results are correspondingly less accurate. The degree of refinement' of the calculations should, of course, be consistent with the conditions involved. If the heat loss from the boiler and piping does not warm the building or is not included in H, the proper allowance should be made. In selecting a boiler, this allowance is frequently assumed to be 25 per cent of the total heat loss of the build ing, but in estimating fuel requirements, the more accurate procedure of computing the pipe and boiler losses should be used, unless this item is likely to be outweighed by other less tangible factors. Where temperature control is installed the fuel consumption can obviously be predetermined with greater accuracy than where no such control has been provided. In fact the calculated requirements agree to a remarkable extent in many cases with the actual fuel consumption. This has been particularly true of gas-fired installations, with which effective temperature regulation usually is possible. Where other heat sources are available it quite often is possible accu rately to allow for the reduction in the fuel consumption resulting there from. These sources include the heat supplied by persons, lights, motors and machinery, and should also be ascertained in the case of theaters, assembly halls and industrial plants. (See Chapter 2). ' In many cases these heat sources should not be allowed to affect the size of the instal lation of heating equipment, although they may have a marked effect upon the fuel consumption. In residences this factor usually may be entirely neglected. Degree-Day Method A very useful unit for estimating fuel consumption, particularly for residences, is the degree-day. (See definition in Chapter 1). Degree-days for various cities in the United States and Canada are given in Table 6. The term degree-day originated in .the gas industry and was later, stand ardized by the American Gas Association. 268 Chapter 16--Fuels Table 6. Degree-Days for Cities in the United States and Canada Col. A State Col. B City Col. C Degree-Days Col. A State Col. B City Col. C Degree-Days Ala.. Mobile......................... 1,439 Birmingham.............. 2,527 1,446 Flagstaff--........ ....... 10,913 Art- 2,665 Little Rock...... ......... 2,861 Cal-.......- San Francisco........... 3,450 1,517 Pnln 5.880 Grand Junction........ 5,570 6,039 n r 4,562 Fla 1,080 r;a 2.880 1,517 4,924 6,459 Til 6,300 Springfield.................. 5,495 Ind.--........ 5,331 3,355 6>44 6,464 5,282 Dodge City................ 5,035 Ky. ........ - Louisville.................... 4,366 1,044 Shreveport................. 2,097 Me--........ . 8,676 7,267 Md. --..... 4,591 6,055 8,319 Detroit.--................... '6,202 Marquette..... ............ 8,866 . 9,650 Minneapolis............... 7,953 Miss..a..... Jackson........................ 1,920 Mo___ ____ 5,289 St. Louis..................... ' 4,583 4,650 6,983 8,608 Nebr......... 6,231 North Platte............ : 6,479 Nev..,____ N. H....... N. J.......... N. Y. N. M. N. C. N. d; ... Okla.. Pa............... R. I... . S. C. S. D______ Utah......... Vt._ Va.............. Wash____ _ W. Va....... Wis............ Wyo____.... Tonapah..................... Winnemucca............. Atlantic City............ Buffalo........................ New York--............... Wilmington...... ......... . Pittsburgh.................. Nashville.... .............. Galveston................... Lynchburg...... ........... Danville...................... Seattle. -.................. Spokane...!!................. Parkersburg.............. Cheyenne................... 6,069 6,266 7,335 5,250 6,542 6,750 5,348 6,064 3,287 2,493 8,498 9,724 6,096 5,426 3,827 4,449 4,629 4,950 5,327 6,111 1,770 2,600 7,213 7,683 3,517 3,550 1,912 1,050; 1,362 5,358 6,750 8,123 3,789 3,849 3,316 3,349 5,156 6,085 5,813 4384 8,201 , 7,309 7,366 8,113 7,360 Col. A Province Col. B City Col. C Degree-Days Col. A. Province Col. B City Col. C Degree-Days B.C______... Alb........... Sask. ___ : Man_____ Ont................ Victoria_____________ Vancouver..... ;........... Kamloops................... Medicine Hat...^............. Qu Appelle...................... . Winnipeg................................. Port Arthur......................... 5,777 5,976 6,724 8,152 11361 11,166 10,803 Ont.................. 1Que............... .. N. B................. N. S---------- P. E. I....... Montreal... :....................... Quebec........................................ Frederickton....... . Yarmouth. ...................... Charlottetown................. '8,705 8,628 9,099 7,694 8,485 269 4