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Electric Tank Water Heater Since the input and output are the same for an electric tank water heater, this can be expressed as: Electric Tank Input (Kw) > Circulation loop heat loss (Btu/h) 3413 (1 Kilowatt = 3,413 BTU) Gas Tank Water Heater When using a gas style water heater, the efficiency of the tank must be taken into account. Available Btu output = (Btu input of tank) x (efficiency) > Circulation loop heat loss (Btu/h) Example: 30,000 Btu input gas tank 0.62 Efficiency 30,000 x .62 = 18,600 available Btu output Additional Guidelines Tankless water heaters not recovering a storage tank: In applications involving a commercial dishwasher, a hot water circulation loop feeding the dishwasher is required. Tankless water heater recovering a storage tank: In applications involving a commercial dishwasher, a hot water circulation loop feeding the dishwasher may be required depending on the distance between the dishwasher and the storage tank. Refer to local codes when determining the need for circulation loops to dishwashers. 6 Pump Sizing for Storage Tank Application The following applies when using tankless water heaters to recover a storage tank. Drawing WH-1-B is an example. Tankless water heaters have a pressure loss which must be considered in the system design. Reference the pressure loss curve for the heater model being used to determine the pump size for the desired recovery rate. For recommended pump sizes use the table below. Additional pressure losses in plumbing between the Heater(s) and the storage tank must also be taken into consideration. The specified pump size is to provide maximum recovery of the storage tank. A smaller pump size may be used, but could result in longer recovery time of the tank. Please contact the Tech Services department with any questions on pump sizing. NOTE: Only use pumps of brass or stainless steel construction. Do not use pumps of iron construction as they will oxidize and clog the inlet filter on the appliance. Pump Flow Requirements Number of Tankless Water Heaters 705/505 305 1 6 gpm @ 30' head 5 gpm @ 25' head 2 12 gpm @ 30' head 10 gpm @ 25' head 3 18 gpm @ 30' head 15 gpm @ 25' head 4 24 gpm @ 30' head 20 gpm @ 25' head 5 30 gpm @ 30' head 25 gpm @ 25' head 6 36 gpm @ 30' head 30 gpm @ 25' head 7 42 gpm @ 30' head 35 gpm @ 25' head 8 48 gpm @ 30' head 40 gpm @ 25' head 9 54 gpm @ 30' head 45 gpm @ 25' head 10 60 gpm @ 30' head 50 gpm @ 25' head 11 66 gpm @ 30' head 55 gpm @ 25' head 12 72 gpm @ 30' head 60 gpm @ 25' head 13 78 gpm @ 30' head 65 gpm @ 25' head 14 84 gpm @ 30' head 70 gpm @ 25' head 15 90 gpm @ 30' head 75 gpm @ 25' head 7 Pressure Loss Curves Pressure Loss (ft head) Pressure Loss Curves Pressure Loss (ft head) 45.0 40.0 8 Pressure Loss (psi) 705 305i505 305e 60.0 35.0 50.0 30.0 40.0 25.0 20.0 30.0 15.0 20.0 10.0 10.0 5.0 0.0 0.0 01 234 56 78910 11 Water Flow (gpm) G as S upply 3/ 4 " C old W ater S upply Line3/4" Hot Water Supply Line TanklessWater Heater TanklessEquipment ListTankles...

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