Document 7O16y5ye9kR5VezxEoNLO2Qk8

I HEATING VENTILATING AIR CONDITIONING CUIDE 1944 CHAPTER 16. HOT WATER HEATINC SYSTEMS AND PIPINC atmosphere. The minimum contents of an open tank should be 0.06 of the volume of the water in the system including that in the boiler, heat transmitters, pipes, etc. This capacity is 50 per cent in excess of the actual increase in volume of water due to increase in temperature from 40 F to 200 F. The tank should be located at least 3 ft above the highest radiator. Provision must be made to prevent freezing of the water in the tank as well as in the pipe leading to the tank. In a thermally circulating hot water heating system, the pipe to the open expansion tank should be connected to the supply riser from the boiler, so that the air liberated from the water in the boiler will enter the expansion tank. In a forced circulating hot water heating system, the pipe to the open expansion tank should be connected on the suction side of the circulating pump, so that the pressure head on the suction side of the pump will remain practically constant. A closed expansion tank is sealed against free venting to the atmos phere. The tank may be above the highest radiator or heat transmitter, or may be below the lowest one. The minimum contents of a closed expansion tank must be such that the expansion of the water due to increase in temperature will be cushioned against a reservoir of compressed air above the water level in the expansion tank. The tank must providespace not only for the change in water volume, but also for variations in air volume within the tank due to changes in air pressure. If the closed expansion tank is below the heat transmitters, the tank should be larger than if it is above-them, and the higher the building, under such circum stances, the larger should be the air capacity within the tank in excess of that required merely for increase in water volume due to temperature increase.. The size of a basement-located closed expansion tank should be at least equal to the following: One story buildings: x = 0.10 V Two story buildings: *.= 0:-13-K_ Three story buildings: * = 0.17 V Six story buildings: x = 0.28 V where X = expansion tank size in gallons. V = water volume in heating system in gallons. Table 4. Friction Heads (in Milinches) of Central Circular Diaphragm Orifices in Unions (iOne.mUinch equals 0.001 in.) Dukbteb Veloott or Waxes in Pxfb in Feet pea Minute or Orifices 20 j 30 j 40 | 50 j 60 j 90 (Inches) 10 IS %-in. Pipe 120 | 180 0 0TM 0" 35 0.55 0 3s 0 0 4S 0^65 1300 650 330 170 2900 1450 740 380 185 5000 2500 1300 660 330 155 75 11,300 5700 2900 1500 740 350 170 20,800 32,000 10,400 16,000 5200 8000 2600 4000 1300 2000 620 970 300 480 45,000 23,000 57,000 12,000 26,000 6800 13,000 2900 6500 1400 3200 700 1600 ,1)00 24,000 53,(XX) 12,000 27,000 5700 13,000 2800 6400 900 2000 3500 460 1000 1800 77ft 570 1000 160 330 580 190 330 200 120 1-in. Pipe 7800 4000 2300 1400 '750 440 260 14,000 . 7200 4100 2300 1300 800 460 22,000 12,000 6400 3700 2200 1300 720 32,000 17,000 9300 5400 3000 1800 1100 37,000 21,000 12,000 7000 4200 2400 65,IXX) 37,000 22,000 50,000 13,000 28,000 7400 17,000 4300 10,000 0.45 0.50 n ss n 0 6* 0.70 0.75 1000 660 430 TAft 190 2250 4000 1450 . 2600 950 1700 630 1100 420 750 285 510 190 330 1/4-in. Pipe . 8900 5800 3800 2500 1700 1150 750 16,000 10,400 6800 4400 3000 2000 1300 25,000 16,400 10,500 6900 4700 3100 2100 36.000 23.000 15.000 10,000 6700 4500 3000 53.000 34.000 22,000 15,000 10,000 6700 60,000 40,000 27,000 60,000 18,000 40,000 12,000 26,000 0.55 ft.rift ft.ris ft 7ft ft 75 nan 0.85 850 1900 3300 600 1300 2300 400 850 1500 260 600 1100 180 400 760 300 540 200 380 1 Vrin, Pipe 7400 5400 3600 2600 1800 1200 860 13,000 8600 7200 4400 3000 2200 1600 21,000 16,800 10,400 7000 5000 3200 2300 30.000 21.000 14,000 10,000 7000 5000 3000 50,000 30,000 21,000 14,000 10,200 7800 53,000 39,000 28,000 19,000 45,000 13,000 30,000 This condition favors, especially in tall buildings, the placing of the closed expansion tank above the highest heat transmitter. Any closed expansion tank located above the heat transmitters of a hot water heating system should be connected by a direct pipe with the flow main leaving the boiler, iri order to enable the air to pass easily to the expansion tank. In a closed hot water heating system the water under pressure tends to absorb air at a rate increasing with pressure increase and decreasing with temperature increase. 0.70 0.80 0.90 1.00 1.10 1.20 1.30 890 1850 3500 470 975 1800 255 560 1000 160 340 610 214 375 195 S-in. Pipe 7400 3900 2200 1320 850 460 275 14,000 7400 4200 2520 1600 950 525 22,300 11,700 6500 4000 2500 1360 980 33,000 17,000 9500 5800 3700 1910 1375 37,000 20.500 12.500 7900 4200 3100 38.000 23.000 49.000 14.000 30.000 8100 16,800 4400 8850 : Means must be provided to adjust and to observe the proportion of air within any closed expansion tank. This involves the provision of an air inlet valve, a water gage and a relief valve. A source of supply of com dpuracctetidcablylytthreueTeinxathseEtnegsitnseteoridnegteErxmpienreimtneentloSsstaestio0n1 ,naenadu amlsouuinultchsemtes7t4s-uto*..determine the losses of h--ead f pressed air for renewing the air cushion is highly desirable, especially in in orifices in 4-in., 6-in., and 12-in. pipe, conducted by the Engineering Experiment Station of the University of Illinois, (Bulletin.10Q, Table 6, p. 38. Davis and Jordan). 310 311