Document MG79Ym54pVarBK4Ne9wYKqpz9

HEATINC. VENTILATING AIR CONDITIONING GUIDE 1943 order that the heating capacity and consequently the size of the heater, or the load on the heating boiler may be as small as possible. In estimating the hot water which can be drawn from a storage tank it should be borne in mind that only about 75 per cent of the volume of the tank is available, as by the time this quantity has been drawn off the incoming cold water has cooled the remainder down to a point where it can no longer be considered hot water. Where steam from the heating boiler is used to heat domestic hot water, the computed load on the boiler should be increased by 4 sq ft EDR (equivalent direct radiation) for every gallon of water per hour heated through a 100 F rise. The actual requirement is ----~ 3.48 sq ft per gallon of water heated 100 F. The value of 4 allows for transmission losses, etc. There are two ways in common use of estimating the hot water require ments of.a building; first, by the number of people and second, by the number of plumbing fixtures installed. Where the number of people to be served is known or can be reasonably estimated, the data in Table'10 may be used. Example 6. From Table 10, a residence housing five people would have a daily requirement of 5 X 40 = 200 gal per day, and a maximum hourly demand of 200 X M = 28.5 gal. The heater should have a storage capacity of 200 X 3^ = 40 gal and a heating capacity of 200 X M = 28.5 gal per hour. The conditions given in Example 6 may be cited as average. It is possible to vary the storage and heating capacity by increasing and Table 10. Estimated Hot Water Demand per Person for Various Types of Buildings Type of Building Res., apts., hotels, etc. Hot Water Required at 140 F Max. Hourly Demand in Relation to Day's Use Duration of Peak Load Hours Storage Capacity in Relation to `Day's Use Heating Capacity in Relation to Day's Use . 40 gal per person per day - h ; 4 H' Office buildings ' 2 gal per person per day k \ 2 . k .: k Factory-r. buildings . 5 gal per . person per day H' T k H Restaurants $0.50 meals . $1.00 meals $1.50 meals 1.5 gal per meal 2.5 gal per meal 4.5 gal per meal Ho , Ho'. Restaurants, 3 meals per day . *0 8 k . Ho. . Restaurants'' 'i 1 meal per day k 2 96 : , . y 834 CHAPTER 45. WATER SUPPLY PIPING AND WATER HEATING Table 11. Hot Water Demand per Fixture for Various Types of Buildings Gallons of water per hour per fixture, calculated at a final temperature of lJfl F Apart ment House Club Gym nasium Hos pital Hotel Indus trial Plant Optics Build* ino Private Resi School dence Y.M. CA. Basins, private lavatory..... 2 2 2 2 2 2 2 2 2 2 Basins, public lavatory....... 4 6 8 6 8 12 6 15 8 Bathtubs-........................... 20 . 20 30 20 20 30 20 30 Dishwashers........ -........... 15 50-150 50-150 50-200 20-100 15 20-100 20-100 Foot basins.--.................... 3 3 12 3 3 12 Kitchen sink--........... . 10 20 20 20 20 3 3 12 : io 10 20 Laundry^ stationary tube.... 20 28 -- 28 28 ' - 20 28 Pantry sink. ....-............. 5 10 10 10 5 10 10 Showers..................... -....... 75 150 225 75 75 225 75 225 225 Slop sink............................. 20 20 20 30 20 15' 15 20 20 Hourly heating capacity factor--...... -.................. Storage capacity factor....... 30% 30% 125%' ' 90% 40% '100% 25% 25% 60% ' 80% 40% 100% 30% `200% 30% 70% 40% 100% 40% 100% decreasing one over the other. Such a condition is illustrated in Ex ample 7. Example 7. Assume an apartment house housing 200 people. From the data in Table 10: Daily requirements -- 200 X 40 = 8000 gal. Maximum hours demand = 8000 X K = 1140 gal. Duration of peak load = 4 hours. Water required for 4-hour peak = 4 X 1140 = 4560. If a 1000 gal storage tank is used, hot water available from the tank = 1000 X 0.75 = 750. Water to be heated in 4 hours = 4560 -- 750 = 3710 gal. Heating capacity per hour = = 930 gal. If instead of a 1000 gal tank, a 2500 gal tank had been installed, the required heating .. ,, , 4560 - (2500 X 0.75) . capacity per hour would be----------------- -r--------------- = b71 gal. In cases where the number of fixtures only are known, the data in Table II have been found satisfactory. . Example 8. An apartment building has a hot water requirement as follows: 60 lavatories............................ ............................ ......................... X 2 = 120 gal per hour 30 bath tubs--................... ........................................................... X 20 = 600 gal per .hour 30 showers...... ...... ..............................................................-.....--- X 75 = 2250 gal per hour 60 kitchen sinks.--.........'.......... ........................... :...................... X 10 = 600 gal per hour 15 laundry tubs............ ........ ........................... ........................ :.. X 20 = 300 gal per hour Maximum hourly requirement................................... ........................ -- = 3870 gal per hour Hourly heating capacity.___________________ -- = 3870 X 0.30 = 1161 gal per hour Storage capacity.__ _________................... .............. = 1161 X 1.25 = 1450 gal per hour METHODS OF HEATINC WATER Hot water may be heated either by the direct combustion of fuel, by an intermediate carrier such as steam or hot water, or by electrically heated 835