Document pvEgmj4X4OnJxpO62xa4Bdow

American Society 0/ Heating and Ventilating Engineers Guide, 1935 Table 11. Ordinary Maximum Hourly Demand for Hot Water for Various Fixtures in Gallons and Probable Percentage of Usage Ttfb of Building Maximum Pbobablb Usage GPU Lavatories Private Public Bathb Showers Slop Sines Kitchen Pantht Sines Sines Foot Baths Wash Trats Av. Max. Use* 20 20 40 300 30 30 20 20, 50 Probable Usage in Per Cent of Maximum Ordinary Use Apt. house Club Gym. Hospital Hotel Industrial Laundries Office building' Baths Residences Schools Y. M. C. A. 25 50 33 67 67 33 50 25 60 35 25 75 50 67 67 67 100 25 80 60 25 100 100 100 100 80 25 75 50 33 67 67 100 25 80 45 25 100 50 33 100 67 100 25 80 70 25 . . 150 100 100. 67 67 100 90 25 100 25 75 ... .... . 33 50 100 100 20 25 150 150 TOO 50 100 25 - 50 33 50 33 50 50 60, 50 25 75 . 100: 67 33 100 50 ...... 25 25 100 100 100 67 67 100 100 80\ 75 Percentage of fixtures likely to be demanding maximum probable usage at any one time. Table 12. Hot Water Consumption in Various Types of Buildings ' for Different Purposes Type or Building Conditions Gallons Hotels Public ' Buildings Industrial Buildings Restaurants Room with basin only Room with bath * (Transient) (Men) (Mixed) . (Women) Two-room suite and bath Three-room suite and bath 10 (per day) 40 (per day) 40 (per cTay) " ~ 60 (per day) 80 (per day) 80 (per day) 100 (per day) Public bath or lavatory 150 (per day per fixture) Public shower 200 (per day per fixture) Public lavatory with attendant 200 (per day per fixture),. Per office employee Per factory employee Cleaning floors, 2 (per day) 5 (per day) 3 (per 1000 sq ft per day) $0.50 Meals " $1.00 Meals . $1.50 Meals 0.5 (per customer with hand washing) 1.0 (per customer with machine washing) 1.0 (per customer with hand washing) 2.0 (per customer with machine washing) 1.5 (per customer with hand washing) 4.0 (per customer with machine washing) Chapter 35--Water Supply Piping t . and the storage required only 500 = 667 gal. 0.75 Good design requires that the heating capacity be made as small as possible without introducing undesirable amounts df storage, as the heating capacity directly determines the load on the source of heat. As indicated in Example ,5j the heating lpajd Js. proportional to the heating capacity and the boiler capacity must be increased for higher heating capacities and may be reduced for smaller heating capacities with greater storage. It may be assumed that a boiler capacity of about. 3}^ sq ft' of equivalent steam heating surface (radiation) must be provided for every gallon of water heated 100 F or from 50 F td 150 F, which is the temperature rise most commonly assumed and . required. On this basis it will be seen that the various conditions cited in Example 5 will require additional boiler capacity as follows: Heating Capacity feph) 833 1200 1500 Additional Boiler. Capacity . (Sq Ft EDR) 2916 4200 5250 From this it is apparent that it is less costly to provide ample storage and to reduce boiler capacity than to diminish the storage and supply a greatly increased boiler capacity to compensate. ESTIMATING HOT WATER DEMAND BY FIXTURES In buildings where the occupancy is doubtful and only the number of plumbing fixtures can serve as a basis for determining the probable hot water demand, the problem is not so simple owing to the fact that a fixture gives" no information as to how" heavy a service may be demanded from the fixture and this amount of service is really the governing factor in making an estimate of the probable hot water demand. Table 11 may prove of some, value in this respect as .it gives the maximum, assumed quantity of hot water per hour which will be demanded of any fixture and then gives a percentage of this amount which may be assumed as probable in different types of buildings. Table 12 giyes approximate hot water re quirements in various types of buildings. Example 6. Let it be assumed that an apartment house with 20 apartments has 20 baths, 20 lavatories, 20 kitchen sinks and 20 laundry trays; what is the probable maxi mum hourly.demand lor hot water? 20 Baths at 40 gal and 33 per cent.:...:..:., 1.............................................. 270 gal 20 Lavs, at 20 gal and 25 per cent........................................ ........................... 100 gal 20 Sinks at 30 gal and 33 per cent..... --;.. 200 gal 20 Trays at 50 gal and 60 per cent............................................................ ....... 600 gal Total.:,....... i...........................................:........... ......... . ......... .................. . ..........1170 gal Probable peak' use at one time.................................................. ..................... 35 per cent Probable, actual peak demand...................... 409 gph 100 X S 33 , `Actual requirement for 100-deg tempeiature.difference = ----^ ^'-- ?* 3.33 sq ft per gallon o water heated. - 619