Document Kq6XXaDkYjBXELx1Q6JmBv5K

426 CHAPTER 20 1949 Guide.; Table 2. Unit Fuel Consumption Constants (V) fob Gas* Baaed on 0 F Outside Temperature, 70 F Inside Temperature; and 8-Hour Reduction to 60 F. Heating Value or Gas Btu fee Cu Ft 500 535 800 1000 Hot Water Cu Ft Gas per Degree-Day per Sq Ft Radiator Up to 500 Sq.Ft 500 to 1200 Sq Ft Over 1200 Sq Ft 0.142 0.132 0.089 0.071 0.135 0.126 .0.085 0.068 0.128 0.120 0.081 0.065 Steam Warm Air Cu Ft Gas per Degree-Day per Sq Ft Radiator Up to 300 Sq Ft 300 to 700 - Sq Ft Over 700 Sq Ft Cu Ft Gas per Degree-Day per 1000 Btu Hourly Design Heat Loss Gravity Fan Systems 0.242 0.226 0.151 ' 0.121 0.231 0.215 0.144 0.115 0.220 0.206 0.137 0.110 0.855 0.800 0.534 0.428 0.820 0.766 0.513 0.410 1 Therm 100,000 Btu Gas Consumption in Therms per Degree-Day 0.000642jo.00121 0.000708 0.000675 0.00115 0.00110 0.00428 0.00409 * Abstracted from Comfort Heating, American Qas Astociaixon, 1938. tions. For other outside design conditions .corrections must be made as given, in Table 5. The factors in Table 2, as corrected if necessaiy, are- satisfactory for regions having 3500 to 6500 degree-days per heating season. In regions with less than 3500 degree-days the unit gas consumption is higher than given; where over 6500, the unit is less than given. Ten per cent addition or deduction in these cases is recommended by A.G.A. publications. Esti mates for industrial buildings.where low inside temperatures are maintained cannot be made from this table: ' For gas heating values other than those given in Table 2, simply inter polate or extrapolate. It will also be noted that Table 2 applies only to small installations. In'general the larger the installation the smaller the unit gas consumption becomes and the values in the table should be used with care, if at all, in large gas-burning installations. Example 6. Estimate the gas required to heat a building located in Chicago, 111., which has 6282 degree-days and a gas heating value of 800 Btu per cu ft. The calcu- . Tablb 3. Unit Fuel Consumption* Constants (U) fob OiLb Based on 0 F Outside Temperature, 70 F Inside Temperature, and 8-Hour Reduction to 66 F : Untto 40 Gal Oil per Sq Ft Steam Radiator.. 0.00172 EmcnaicT in Per Cent so 60 70 0.00137 .0.00114 0.00098 80 0.00086 Gal Oil per Sq Ft Hot Water Radiator._ 0.00108 0.00086 0.00072 0;00062 0.00054 Gal Oil per 1000 Btu per Hour Heat Loss. __ ____ . . .. 0:00715 0.00571 0.00476 0.00409 0.00358 .Based on a beating value of 140,000 Bhij>er gallon! .. . ' * , . -- Abstracted by permission from Degree-Day Handbook (Second Edition, 1937), by C. Strock and C. H. B. _ Hotchkiss. .1 '0Per degree-d&y. Estimating Fuel Consumption for Space Heating 427 Table 4. Unit Fuel Consumption* Constants (U) fob Coal6 Based on 0 F Outside Temperature, 70 F Inside Temperature, and 8-Hour Reduction to 65 F. Uneto 40 . Etticienct in Per Cent 50 ` 60 70 80 Lb Coal per Sq Ft Steam Radiator.. - 0.0200 0.0160 0.0133 0.0114 0.0100 Lb Coal per Sq Ft Hot Water 0.0125 . 0.0100 0.0084 0.0072 . 0.0063 Lb Coal per 1000 Btu per Hour Heat Loss________________ ______ 0.0825 0.0666 0.0550 010471. 0.0412 Based on a heating value of 12,000 Btu per pound. Abstracted by permission from Degree-Day Handbook (Second Edition, 1937), by C. Strock and C. H.B Hotchkiss. r Per degree-day. lated heating surface requirements are 1000 sq ft of hot water radiation based on design temperature of -- i0 F and 70 F. Solution. From Table 2, the fuel consumption for a design temperature of 0 F with 800 Btu gas is found to be 0.085 eu ft of gas per (degree-day) (square foot of hot water radiation). From Table 5, the correction factor is 0.875 for --10 F outside design temperature, hence 0.875 X 0.085 = 0.07438. By. Equation 4, / F = 0.07438 X 1000 X 6282 =. 467,255 cu ft. Estimating Oil Consumption Unit fuel.consumption factors for oil, similar to those for gas in Table 2, are given in Table 3. The factors in Table 3 apply only to an inside design temperature of 70 F and an outside design temperature of 0 F. For other outside design temperatures, the constants in Table 3 must be multiplied by the values in Table 5 as explained under Estimating Gas Consumption. Values given in Table 3 assume the use of oil with a heating value of 140,000 Btu per gallon. For other heating values, multiply the values in Table 3 by the ratio of 140,000 divided by the heating value per gallon of fuel being used. .. Example 6. Estimate the seasonal oil consumption of an oil-fired boiler in a build ing located in Minneapolis having a calculated heat loss of 192,000 Btu per hr, burning 144,000 Btu per gal oil and operating at a seasonal efficiency of 60.per cent. The out side design temperature for Minneapolis is --20 F, and the inside design temperature is 70 F. Solution. From Table 3, under 60 per cent efficiency and opposite the bottom column, the value of U is found to be 0.00476 gal per 1000 Btu hourly heat loss forO F outside temperature. Table 5. Cobbection Factobs fob Outside Design Tbmpebatubes* Outside Design Temp. F Deg__ Correction Factor -- 20 0.778 -10 0.875 0 . 1.000 +10 1.167 20. 1.400 * The multipliers in Table 5, which are high for mild climates and low for oold regions, are not in error as might appear. - The unit figures in Tables 2,- 3, and 4 are per square foot' of radiator or thousand Btu heat loss per degree^iay. For equivalent buildings and heating seasons, those in warm climates have lower design . heat losses and smaller radiator quantities than those in coFd cities. Consequently, the unit figure in quantity of fuel per (square foot of radiator! (degree-day), is larger for warm localities than for colder regions. Sines the northern cities have more radiator surface per givea building and a higher seasonal degree^day total cities in the south, the total fuel per season will be larger for the northern oity.