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DURA-POWER MODELS NW 37- 670
COMMERCIAL ELECTRIC WATER BOILERS
• Installation • Operation • Service • Maintenance • Limited Warranty
CAUTION
TEXT PRINTED OR OUTLINED IN RED CONTINS INFORMATION
STANDARD
RELATIVE TO YOUR SAFETY. PLEASE READ THOROUGHLY
BEFORE INSTALLING AND USING THE APPLIANCE.
FLOOD WARNING
IF THE BOILER SHOULD BECOME IMMERSED IN
WATER AT ANY TIME, THE BOILER SHOULD BE
EXAMINED BY A COMPETENT SERVICE PERSON A DIVISION OF A.O. SMITH CORPORATION
RENTON, WASHINGTON
BEFORE
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DIMENSIONAL DATA SIZES AND DATA 45KW THRU 720KW Model Number Inlet* & Boiler Prefix Gal.Cap. Std.KWInput D E F G** H J K S T U Outlet* Drain NW 37 45K 32 30 12 42 12 1/2 - - 20 4 42 3 1 NW 37 60K 32 30 12 42 12 1/2 - - 20 4 42 3 1 NW 37 75K 32 30 12 42 12 1/2 - - 20 4 42 2 1 NW 37 90K 32 30 12 42 12 1/2 - - 20 4 42 3 1 NW 37 105K 32 30 12 42 12 1/2 - - 20 4 42 3 1 NW 37 120K 32 30 12 42 12 1/2 - - 20 4 42 3 1 NW 37 150K 32 30 12 42 12 1/2 - - 20 4 42 3 1 NW 37 18
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SIZES AND DATA 780KW THRU 3300KW Model Number Inlet* & Boiler Prefix Gal.Cap. Std.KWInput D E F G** H J K S T Outlet* Drain NW 220 780K 60 50 25 71 21 2 25 1/2 30 5 1/2 5 1 1/2 NW 220 840K 60 50 25 71 21 2 25 1/2 30 5 1/2 5 1 1/2 NW 220 900K 60 50 25 71 21 2 25 1/2 30 5 1/2 5 1 1/2 NW 220 960K 60 50 25 71 21 2 25 1/2 30 5 1/2 5 1 1/2 NW 220 1020K 60 50 25 71 21 2 25 1/2 30 5 1/2 5 1 1/2 NW 220 1080K 60 50 25 71 21 2 25 1/2 30 5 1/2 5 1 1/2 NW 220 1140K 6
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ELECTRICAL/RECOVERY DATA WATER BOILER SPECIFICATIONS Model Number Gal. Std. KW BTU Output Gal./Hr. Number of Number of Standard Number Amperage 3 Phase Prefix Cap. Input 100°F Rise Elements Steps and KW of Steps 208v 240V 480V 575V NW 37 45K 153,585 180 3 1 1@45 128 108 55 45 NW 37 60K 204,720 240 4 1 1@60 171 144 73 60 NW 37 75K 255,975 300 5 1 1@75 213 180 90 75 NW 37 90K 307,170 369 6 3 3@30 250 217 108 90 NW 37 105K 358,365 430 7 4 3@30+1@15 292 253 126 105 NW 37 120K 409,560 492 8 4 4@
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FOREWORD APPROVALS INSTALLATION CODE REQUIREMENTS These designs comply with requirements of Underwriters Laboratories In addition to these instructions, the equipment shall be installed in accordance with those installation regulations in force in the local and bear the U.L. label on the cabinet. area where the installation is to be made. These shall be carefully All models are built to the standards of Section lV of the American followed in all cases. Authorities having jurisdiction should be
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IMPORTANT LOCATING THE BOILER IT IS RECOMMENDED THAT A QUALIFIED SERVICE TECHNICIAN For the best installation, the boiler should be located: PERFORM THE INITIAL FIRING OF THE BOILER. AT THIS TIME 1. On a level surface. THE USER SHOULD NOT HESITATE TO ASK THE TECHNICIAN ANY QUESTIONS WHICH THEY MAY HAVE IN REGARD TO THE • Shim the channel type skid base as necessary if leveling OPERATION AND MAINTENANCE OF THE BOILER. is required. BEFORE FILLING THE SYSTEM FOR OPERATION the hot water 2. Near a f
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Calculating Amperage/Overcurrent Protection Portion of Table 310-16 Portion of Table 310-16 Allowable Ampacities of Allowable Ampacities of Insulated The boiler is factory wired for connection to three wire single-phase Insulated Aluminum and Copper- Copper Conductors or three and four wire three-phase branch circuits. In addition, a Clad AluminumConductors Not more than three conductors in ground conductor may be required. raceway or cable or direct burial Not more than three conductors (based
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ELECTRICAL CONFIGURATION TABLE Boiler Type Voltage Between Control Elements Nameplate of Boiler Terminal Circuit Quantity Element Markings Service Lugs Voltage Per Operating Voltage Phase (1 Phase) Contractor Voltage 1 L1 L2 N G 120 1 208 208 120 208 L1 L2 L3 N G 3 Delta 208 208 (With 120 1 208 208 Neutral) 120 L1 L2 G 1 120 1 240 240 240 L1 L2 L3 G 240 240
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WIRING DIAGRAM 480V THREE-PHASE (WYE) SYSTEM CLEANING OPERATION The hot water system should be internally cleaned and flushed to remove contaminants which may have accumulated during installation. GENERAL System cleaning provides chemical stability necessary for component life and system performance. Never operate the heating elements without being certain the boiler is filled with water and a pressure relief valve is installed in the relief Failure to clean the system may cause: valve opening p
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4. Close the vent as water starts to flow from the opening. Place the Tank flushing and circulating pump lubrication should be performed make-up water valve in the desired position. The boiler is now in accordance with the above schedule. Tank sediment removal and ready for START UP and TEMPERATURE REGULATION if being element lime scale removal must be performed when needed as determined by period inspections. Following are the instructions for placed in operation for the first time. perform
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• Use a twisting, pulling action to remove elements scaled 3. If the water was excessively hot, and is now cold, the high beyond the size of the tank opening. temperature cutoff may have operated (manual reset equipped models). • Brush loose scale from elements. • To reset, turn off electricity and remove the back panel and push the reset button. • Silicates, sulfates and aluminates must be removed by • Repeated operation of the high temperature cutoff should scraping or other mechanical means.
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NW-37 THRU NW-670 ELECTRIC HOT WATER BOILER LIMITED WARRANTY A.O. Smith Corporation, the warrantor, extends the following LIMITED WARRANTY to the owner of this boiler. 1. THE TANK If the tank in this boiler shall prove upon examination by the warrantor to have leaked due to natural corrosion from water therein, during the FIRST year after initial installation, the warrantor will at its option, repair it or provide a replacement tank less elements a n d controls of equivalent size and then curren
