Document ByrZZxYb8GL3NErwBL0bNy22L

American Society of Heating and Ventilating Engineers Guide, 1934 H 4-Hi Ht + T If a building has no interior walls or partitions, whatever air enters through the cracks on the windward side must leave through the cracks on the leeward side, and only half of the total crack should be used in computing the infiltration for each side and end of the building. Under these conditions it is sufficiently accurate to use the total calculated heat loss (H) for the building. If the average wind velocity during the heating season differs from that upon which H, was derived, the value of H should be corrected accordingly. Of .course, where the required heating surface is estimated by empirical or rule-of-thumb methods, refinements in approximating fuel consump tion are not warranted, but rule-of-thumb methods often lead to unsatis factory results and should be avoided in heating work where more accurate methods are available. It should be emphasized that the value of H in Equation 1 is the total heat loss of the building after making the proper allowance for infiltration. CALORIFIC VALUES AND HEATINC EFFICIENCIES The calorific values of fuel oils and gas can be ascertained with reason able accuracy. The values for various grades of oil are given in Table 2, Chapter 27. The calorific value of gas can always be obtained from the local utility company. Values for natural gas are given in Table 3, Chapter 27; manufactured gas usually has a cajorific value of about 535. Coals have a larger range and may vary for the same type of coal, depend ing on its ash content. For general purposes where specific data are lacking, values can be taken from the top curve of Fig. 1, Chapter 27. To decide on the correct efficiency to use is a more difficult matter, par ticularly if the estimate is being made without a full knowledge of the equipment for burning the fuel and the care the furnace will receive. Efficiencies usually are given in the catalogs of manufacturers of furnaces and boilers, but these values are obtained under test conditions and do not allow for poor attendance, defects in installation, or poor draft. On the other hand, such efficiencies assume that all the heat radiated from the outside of the heaters or casings as sensible heat of the flue gases is lost, whereas, if the heater is installed in the building being heated, a con siderable portion of these losses may help to heat the building2; how much of this it is legitimate to use in increasing the value of E will depend on whether H included the heat losses in the cellar, and on the construction of the chimney. Except for an interior chimney, the heat transferred through the chimney wall to the building will be very small. Chimney allowances should be greater for lower test efficiencies. Thus, an insulated furnace will give a high efficiency on test but will not heat the cellar. A modern gas furnace will have a high efficiency with a correspondingly low flue gas temperature and hence there will be very little heat from the flue pipe. For great exactitude the value for E should take care of inefficiency in the heat distribution in the! building because of such losses as excessive heating of the walls behind the radiators and excessive stratification., It *Analysis of the Over-AH Efficiency of a Residence Heated by Warm Air, by A. P. Kratz and J. F. Quereau (A.S.H.V.E. Transactions, Vol. 35, 1929). 398 Chapter 29--Fuel Consumption Table 1. Degree-Days for Cities in the United States and Canada* Col. a State Col. B City Col C Degree-Days Col. A State ColB City Col. C Degree-Days Ala.............. Birmingham.... ......... Mobile...... ................. Ariz--...... Flagstaff.................... Tucson....................... Ark............. Hot Springs............. Little Rock.............. Calif........... Los Angeles___ : San Francisco........... Colo............ Colorado Springs.... Denver...................... Conn-------- New Haven.............. D. C........... Washington.............. Fla----------- Jacksonville.............. Ga----- 1....... Atlanta... .................. Savannah.................. Idaho-------- Boise......................... Lewiston.... ............... 111........... Chicago....... .............. Springfield................. Ind............. Evansville................. Indianapolis:............ Iowa........ Des Moines............. Sioux City....... ......... Kan......... _. Dodge City...... ........ Topeka...................... Ky------------ Lexington................. Louisville................... La............... New Orleans............. Me............ Eastport.................... Portland.................... Md.______ Baltimore.................. Mass....... Springfield................. Boston........ .......... ..... Mich........-- Detroit........_______ Marquette............. : Minn._____ Duluth....................... Minneapolis.............. Miss........... Vicksburg................. Mo..._____ Kansas City............. St. Louis.... ............... Mont_____ Billings...................... Havre......................... Neb...... Lincoln....................... Omaha....................... 2,408 1,471 7.145 1,845 2,665 2,811 1,504 3,264 6,553 5,873 5,895 4,626 890 2,891 1,490 4,558 4,924 6,315 5,370 4,164 5,297 6.373 7.023 5,034 5,301 4,616 4,180 1.023 8,531 7,012 4,333 6,464 6.145 6,494 8,692 9,480 7,851 1,822 5,202 4,585 7,115 8,699 6,231 6,128 N. H......... Concord................... N. J..... Trenton........ ............. N. M____ Santa Fe. N. Y......... Buffalo_______ New York. .......... N. C......... Wilmington...... ........ N. D......... Ohio.......... Cleveland.................. Columbus. Okla.... .. Oklahoma City........ Salem........................ Pa............. R. I..... Pittsburgh................. S. C______ Charleston............... Spartanburg.. ......... S. D_____ Sioux Falls................ Nashville...... ............. Dallas........................ Houston............ ........ Utah San Antonio.. ......... Safi Lake City_____ Vt.............. Va.............. Fredericksburg.____ Norfolk;... ................. Richmond.. ........... Wash____ Seattle.. W. Va___ Wis........... Wyo_____ Parkersburg.............. Green Bay................ La Crosse.................. Milwaukee............. . Cheyenne......... ......... 5,891 6,852 5,175 4,934 6,063 6,889 6,821 5.348 3.234 2,302 8,498 4,702 6,154 5,323 3,613 4,468 4,629 4,855 5.235 6,014 1.769 3,257 7,683 2,950 3.578 1.578 2,455 1,157 1,202 6,735 5,553 7,620 4,243 3.349 3,725 4,868 6,353 5,016 4,884 7,612 7,823' 6,690 7,372 7,462 Province City Degree-DayB Province City Degree-Days B. C_____ Victoria Vancouver................. Kamloops.................. Alb______ Medicine Hat._____ Sask.____ Qu'Appelle......... ....... Man_____ Winnipeg.......... ........ Ont............ Port Arthur.............. 5,777 5,976 6,724 8,152 11,261 11,166 10,803 Que........... MontreaL Quebec................. .... N. B.......... Fredericton_____ __ N. S......... Yarmouth...... ........... P. E. I____ Charlottetown.......... 7,732 8,705 8,628 9,099 7,694 8,485 aFrom Industrial Gas Series, House Healing (third edition) published by the American Gas Association. These degree-days are.based on daily mean temperatures. Base,.65 F. 399 i