A.O. Smith NW 37-670 Instruction Manual

[Page 1] A.O. Smith NW 37-670

1 DURA-POWER MODELS NW 37- 670 COMMERCIAL ELECTRIC WATER BOILERS • Installation • Operation • Service • Maintenance • Limited Warranty PLACE THESE INSTRUCTIONS ADJACENT TO THE BOILER AND NOTIFY OWNER TO KEEP FOR FUTURE REFERENCE.BE...

[Page 2] A.O. Smith NW 37-670

2 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 1...

[Page 3] A.O. Smith NW 37-670

3 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...

[Page 4] A.O. Smith NW 37-670

4 ELECTRICAL/RECOVERY DATA MODEL AND RATING PLATE 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 2...

[Page 5] A.O. Smith NW 37-670

5 APPROVALS These designs comply with requirements of Underwriters Laboratories and bear the U.L. label on the cabinet. All models are built to the standards of Section lV of the American Society of Mechanical Engineers. Boiler and Pressure Code, in...

[Page 6] A.O. Smith NW 37-670

6 IMPORTANT IT IS RECOMMENDED THAT A QUALIFIED SERVICE TECHNICIAN PERFORM THE INITIAL FIRING OF THE BOILER. AT THIS TIME THE USER SHOULD NOT HESITATE TO ASK THE TECHNICIAN ANY QUESTIONS WHICH THEY MAY HAVE IN REGARD TO THE OPERATION AND MAINTENANCE ...

[Page 7] A.O. Smith NW 37-670

7 Calculating Amperage/Overcurrent Protection The boiler is factory wired for connection to three wire single-phase or three and four wire three-phase branch circuits. In addition, a ground conductor may be required. A diagram of the wiring is furni...

[Page 8] A.O. Smith NW 37-670

8 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 1 120 1 208 ...

[Page 9] A.O. Smith NW 37-670

9 WIRING DIAGRAM 480V THREE-PHASE (WYE) SYSTEM CLEANING The hot water system should be internally cleaned and flushed to remove contaminants which may have accumulated during installation. System cleaning provides chemical stability necessary for com...

[Page 10] A.O. Smith NW 37-670

10 4. Close the vent as water starts to flow from the opening. Place the make-up water valve in the desired position. The boiler is now ready for START UP and TEMPERATURE REGULATION if being placed in operation for the first time. START UP The foll...

[Page 11] A.O. Smith NW 37-670

11 • Use a twisting, pulling action to remove elements scaled beyond the size of the tank opening. • Brush loose scale from elements. • Silicates, sulfates and aluminates must be removed by scraping or other mechanical means. Lime scale dissol...

[Page 12] A.O. Smith NW 37-670

12 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 war...