Document OEVe6Mv5KmOzVD9yLgYYbba0j

American Society of Heating and Ventilating Engineers. Guide, 1928 Table 2. Areas of Standard Size Pipes of Standard Weight Nominal Sue of Pipe Inches Vi 34 3A 1 1)4 i'A 2 234 3 334 4 5 6 8 10 12 Area of Pipe Sq. In. 0.192 0.305 0.533 0.863 1.496 2.038 3.356 4.784. 7.388 9.887 12.73 19.99 28.89 50.04 78.84 113.10 not usually the case to find much attention given to complicated formulae and curves; this is for the reason that the saving on installations involving only a few hundred dollars is so small as not to justify elaborate engi neering calculation besides which the work itself is generally installed by a competition contractor and no funds are available for which a proper designer could be employed. As a general rule the contractor himself does all the designing which is necessary and he doesn't want to be bothered with any complication which can in any way be avoided. Probably the simplest way of determining hot water pipe sizes in the ordinary small gravity system is the old method of taking the area of each radiator connection or valve and adding these aieas together where the lines join, making the area of combined line practically equal to the sum of all the areas which the line supplies. Thus if a pipe is feeding three radiators, one with a %-in. connection, one with a 1-in. connection and the third with a lj^-in. connection the sum of these areas is as follows: 1 in....................... 0.863 1% in................... 2.038 % in................... 0.533 sq.in. 3.434 sq. in. Referring back to the table it will be found that the pipe which has practically the same area is a 2-in. pipe which has an area of 3.356 sq. in. For jobs of somewhat larger character where too much refinement is Table 3. Square Feet of Radiation Allowable on Risers up to 100 Ft. Height Inches *a......... ............ i..._..... ................ 1)4....................... iy2......................... 2........................... Distance above the Boileb in. Feet 10 20 30 40 50 60 70 80 40 50 60 70 80 90 100 no 70 80 90 100 no 120 130 . 140 no 120 135 150 160 175 185 200 180 . 185 210 230 250 265 285 300 300 350 400 500 575 625 700 775 90 .-100 120 130 150 160 210 225 315 330 825 900 132 Chapter IV--Hot Water Heating Systems and Piping unnecessary but at the same time closer results than that given in the above are desired, the table given below which takes into the consideration the height of the riser available to circulate the line may be recommended. The risers are then connected up to the mains on the basis of allowing a factor for each size of pipe and then adding these factors to obtain the factor corresponding to the proper size of basement main. These factors are as follows: Table 4. Factors for Various Sizes of Pipe in Gravity Hot Water Heating Nominal Size of Pipe Inches 3A l 1)4 2IK 234 3 3A 4 5 6 8 10 12 Factor 5 10 20 30 60 no 175 260 380 650 1050 2250 Thus, if the three radiators previously considered were set and sized as follows; the in. radiator with 20 sq. ft., and located 40 ft. above the boiler; the 1-in. radiator with 40 sq. ft. and set 20 ft. above the boiler and the lj^-in. radiator with 75 sq. ft., and set 10 ft. above the boiler all being on the same riser, the'riser size would be as follows: Riser for 20sq. ft. radiator 40 ft. above.............................. % in. Riser for 40sq. ft. radiator 20 ft. above... ......................... *4 in. Riser for 75sq. ft. radiator 10 ft. above............................. 1)4 in. To combine into one riser take the factors and add; M in...... .-.............. 5factor M in..................... 5 134 in..................... 20 Total............. 30 and the factor 30 is equivalent to a lj^-in. riser. Even if these radiators had all been placed on the first floor, (or 10 ft. above the boiler), the riser size of lj^-in. would still have been sufficient for the three or their equivalent in one radiator. This indicates that the method of combining valve areas gives about one pipe size larger than when more accurately figured. AIR SEALED OR CLOSED HOT WATER SYSTEMS* For many years the closed system of hot water heating in some form has been used successfully abroad, but there has been little thought given to and no research work done in connection with the air sealed, system in this country, so that available data is meagre. For design 'Prepared from data submitted by R. H. Feltwell, Philadelphia and H. A. Thrush, Peru. Ind.