State Industries 317913-000 manuale d’uso

Printed in the U.S.A. 0210 317913-000 A TECHNICAL GUIDE TO DESIGNI NG ENERGY-EFFICIENT COMMERCIAL WATER HEATER SYSTEMS[...]

2 l . Introduction T o Commercial W ater Heating Pages Parameters .................................................................................................................................... 2- 3 What is Hot Water? ............................................................................................................. ........... 3- 4 [...]

3 What is Hot Water? Hot water is water to which heat energy has been added . . .as more heat is added the water becomes hotter . This water temperature guide shows typical water heating system design temperatures. In practice, the system designer will establish the temperature or temperatures of hot water needed for the various activities through [...]

4 Evaluating Water The coldest water inlet temperature experienced during the year should be the base from which the maximum system temperature rise is established. Y our water supplier can provide this information. Surface water sources such as lakes and rivers tend to fluctuate as the seasons change. Well water remains relatively constant in temp[...]

5 Hot Water Demand The major determination in sizing and the basis of all computations is establishing the probable demand for hot water . In addition, any unusual conditions which might relate to hot water consumption must also be recognized and planned for . Unusual conditions will be described under Profiles of Operation. Sources of hot water de[...]

6 • This example could represent an industrial process which is operated for two continuous shifts a day . • Hot water is used at a maximum rate of 3.3 gpm or 198 gph. (It is important to establish maximum flow rate and water temperature rise in order to select a heater model.) • In this example heater recovery is most important as the system[...]

7 When used at altitudes of 2000’ or more above sea level, gas-fired heater recovery capacities must be derated 4% for each 1000’ above sea level in order to reflect actual recovery . Recovery Capacity means hot water at the heater recovery rate minute after minute, hour after hour . If the hot water demand period is more than 3 or 4 hours, rec[...]

8 State commercial tank type water heaters, hot water storage tanks and water heating systems using tanks have assigned tank efficiencies as follows: Gas and Oil-Fired T ank T ype Heaters • Use 70% tank draw efficiency for all one and two temperature applications. For example, a gas fired Ultra Force ® SUF100-150 model has an 100 gallon tank: ?[...]

9 Eight hour demand period, per hour capacity . 171 gph recovery Storage: + 8 gal storage 179 gal/8 hour 100 gallon tank Recovery provides 96% x 70% tank efficiency of demand. = 70 usable gallons over 8 hours 70.0 _ 8 = 7.8 or 8 usable gallons per hour Here’s how it’s figured: 171 gph recovery + 8 gallons storage per hour = 179 gallons of hot w[...]

10 When Using Electricity T o Heat Water The system designer may want to modify the preceding heater recovery and storage tank capacity information when using electricity to heat water . This is because electricity for commercial use, including water heating, is often sold on a demand rate basis. This means, in addition to the energy charge (measur[...]

11 IV . Sy st em T ypes and Application Design Objective The objectives in the design of commercial water heating systems are numerous and varied. The major considerations which the system designer should include in the planning stages are: 1. The heater and related system components and their installation must comply with all applicable codes and [...]

12 2. T wo T emperature provides two temperature hot water service by means of a water mixing valve or through a pre-heater/booster heater combination. In the first concept the heater storage tank is maintained at the highest system temperature required (usually at 180°F) and the mixing valve externally produces the 140°F hot water requirement. T[...]

13 Creating the Successful System Creating the successful commercial water heating system is a joint venture involving many persons and skills. In order to select the right system using either tank type or copper type heaters, one should understand the role that each of the persons concerned with the installation plays. The following chart summariz[...]

14 2. Select a trial size heater 2 / . 3. Subtract the hourly heater recovery from the demand. 4. The difference in gallons between demand and recovery must come from the tank. 5. Multiply the difference by the number of demand hours. The result is the “usable” number of gallons which must come from the tank. 6. Divide the “usable” tank gal[...]

15 T wo temperature example 1. A one hour demand of 75 gallons of 180°F water and 110 gallons of 140°F water has been established. The lowest incoming water temperature is 40°F . The shortest time in any day in which the demand will be repeated is 3 hours. 2. Convert the 180° water requirement into the equivalent of a 140°F water requirement t[...]

16 ST A TE W A TER HEA TERS ASHLAND CITY , TENN. © 200 4 TECHNICAL INFORMA TION 800-365-0577[...]