Document jy150Xy73qVD624MoYRGazxKZ

American Society'o/ Heating and Ventilating Engineers Guide, 1925-26 Table 1. Inside Temperatures Usually Specified Type of Building Deg. Temp. Warm Air Baths.................... ........ 120 ........ 110 85 Bath Rooms........................... ........ 85 Paint Shops.................................... 80 Hospitals..... ........................... ........ 72 to 75 Public Buildings.................... ........ 68 to 72 Deg. Temp. Residences.............................. ... 70 ... 70 65 Stores........... :............................. 65 Gymnasium................................ 55 to 60 Machine Shops..-...................... 60 to 65' Foundries, Boiler Shops, etc.... 50 to 60 In making the actual heat loss computations, however, for the various rooms in a building it is often necessary to modify the temperatures given in Table 1 so that the air temperature at the proper level will be used. By "air temperature at the proper level" is meant, in the case of walls, the air temperature at the mean height between floor and ceiling; in the case of glass, the air temperature at the mean height of the glass, in the case of roof or ceiling, the air temperature at the mean height of the roof or ceiling above the floor of the heated room, and in the case of floors, the air temperature at the floor level. In the case of heated spaces adja cent to unheated (no heat of any kind) spaces, it will usually be sufficient to assume the temperature in such spaces as the mean between the tem perature of the inside heated space and the outside air temperature. The air temperature at the mean height between floor and ceiling is the "breathing line" temperature, Table 1, for rooms not over 10 ft. in height. For rooms above this height, add 2 per cent per foot of height to the breathing-line temperature for each foot or fraction of a foot difference between the mean height of the vertical wall glass roof or ceiling surface, and the height of the breathing line. In determining mean air temperatures just above floors whicf^are next to ground or unheated spaces, a temperature 5 deg. lower than breathing line temperature, may be used, provided breathing-line temperature is not less than 55 deg. fahr. OUTSIDE TEMPERATURE The outside air temperature used in computing the heat loss from a building is seldom taken as the lowest temperature ever recorded in a given locality. Such temperatures are usually of short duration and are rarely repeated in successive years. It is therefore evident that a tem perature somewhat higher than the lowest on record may be properly assumed in making the heat loss computations. The outside temperature to be assumed in the design of any heating system must not be more than 151 deg. fahr. above the lowest recorded temperature as reported by the U. S. Weather Bureau (Table 2) during the preceding 10 years for the locality in which the heating system is There seems to be no agreement in this country at present as to the method of arriving at the proper outside temperature to be used in the calculations or design of a heating system. Some offices use the average of the lowest yearly temperatures for the preceding ten years. The Heating and Piping Contractors' National Association in their Code arrive at the assumed outside temperature to be used in the design by including a factor for wind movement as recorded for the locality in question.' Thus, of two localities with the same minimum recorded outside temperature, the locality having the higher wind velocity would be assigned a lower outside air temperature for the calculation or design of a heating system than the other locality. However, since the effect of wind movement is actually reflected only in the heat trans mission coefficients of wall, roof or glass, and in the inleakage (infiltration) of cold air at the cracks around outside windows and doors, its effect should be applied to the transmission and infiltration coefficients and not to the outside air temperature. In this chapter, the practice of correcting transmission and infiltration coefficients for unusual wind movement is followed and the method discussed in detail. 4 American Society of Heating and Ventilating Engineers Guide, 1925-26 to be installed. The outside temperature assumed and used in the design should always be stated in the heating specifications. Table 2. Climatic Conditions Compiled from U. S. Weather Bureau Records' Col. a State i. Col. B City Col. C Average Temp., Oct. 1stMay 1st Col. D Col. E Col. F Lowest Tempera ture Average Wind Vel ocity Dec., Jan.. Feb.. Miles per Hr. Direction of Prevail ing Wind, Dec., Jan., Feb. Ark................ Birmingham.....................-........... Phoenix..... ............................. -- Flagstaff................... -................... Fort Smith______ :....................... Little Rock. -................................ Pr Grand Junction......... ................... New Haven................................... Ga.............. - Atlanta........................................... Savannah....................................... Lewiston___..................... ....... ..... Pocatello............ ........................... 111 Springfield..... ................................ Evansville...................................... Sioux City.......... -........ ................ Concordia....................................... Dodge City.................................... Kv Shreveport......:..................... -...... Me.... ............ Eastport........ ................................ Portland......................................... Mr! Mass............. Boston............................................ Mich............. Alpena..................................:........ Detroit....................... 1........... ...... Marquette.-- ............................. Minneapolis................................... Mo St. Louis......................................... Springfield..... ................................ Havre..... .... ................................... North Platte..... ............................ N. H............. N. J............... N. Y.... . N. M.. _ .... Winnemucca-- .............................. Albany-- ................................. . Buffalo..... .... ....................... -....... New York-- .................................. Santa Fe........................................ 57.7 53.9 59.5 34.9 49.5 51.6 54.3 58.6 39.3 39.2 38.0 43.2 61.9 51.4 58.4 42.5 36.4 36.4 39.9 40.2 44.1 33.9 32.1 38.9 40.2 45.2 61.5 56.2 31.1 33.6 43.6 37.6 29.1 35.4 27.6 25.1 29.6' 56.0 40.3 43.3 43.0 34.7 27.7 37.0 34.6 39.6 37.9 33.4 41.6 35.1 34.7 40.3 38.0 -i -10 16 -25 -15 -12 29 28 -29 -16 -14 -15 10 ' -8 8 -13 -20 -23 -24 -25 -15 -32 -35 -25 -26 -20 7 -5 -23 -17 -7 -13 -27 -24 -27 -41 -33 -1 -24 -22 -29 -49 -57 -29 -35 -7 -28 -35 -7 -24 -14 -6 -13 8.3 8.6 3.9 6.7 8.0 9.9 7.4 5.6 9.3 7.3 8.2 11.8 8.3 4.7 9.3 17.0 10.2 11.8 8.4 6.1 12.2 7.3 10.4 9.3 9.6 7.7 13.8 10.1 7.2 11.7 11.3 13.1 11.4 11.1 11.5 7.6 9.1 11.8 11.3 8.7 10.9 9.0 9.9 9.5 6.0 10.6 7.9 17.7 13.3 7.3 N N E sw E NW N NE S SE N NW NE NW NW E SE SW NW S S NW NW N NW SW. N SE W NW NW W W. SW NW SW NW SE ' NW NW ' SE W SW N W. SE NE NW NW S w NW NE 5