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10

requIred aBIlIty

Installation and service of this boiler requires ability equivalent to that 

of a qualified agency (page 2) in the field involved. Plumbing and 

electrical work is required.

General

The  installation  must  conform  with  these  instructions  and  the 

local  code  authority  having  jurisdiction  and  the  requirements  of 

the power company. In the absence of code requirements, follow 

NFPA-70  (current  edition).  In  the  absence  of  local  codes,  the 

installation  must  comply  with  the  latest  editions  of  the  National 

Electrical  Code,  NFPA  70  or  the  Canadian  Electrical  Code  CSA 

C22.1.  The  National  Electrical  Code  may  be  ordered  from: 

National Fire Protection Association, 1 Batterymarch Park, Quincy, 

MA  02269.  The  Canadian  Electrical  Code  is  available  from  the 

Canadian Standards Association, 8501 East Pleasant Valley Road, 

Cleveland, OH 44131.

Do 

not 

test  electrical  system  before  boiler  is  filled  with  water, 

follow the START UP procedure in the OPERATION section of this 

manual.

The principal components of the boiler are identified in the Features 

and Components illustration on page 8.

Boilers are usually placed in a series with the heating system on 

the outlet side of the circulating pump. The boiler piping should 

include inlet and outlet water valves to permit maintenance and 

service  work  to  be  performed  without  disturbing  the  rest  of  the 

system.

Detailed system installation drawings are normally provided by the 

equipment purchaser or system designer.

pressure relIef ValVe

An ASME rated pressure relief valve is furnished with the boiler. A 

fitting for the relief valve is provided in the top of the boiler. Never 

operate the heating elements without being certain the boiler is filled 

with water and a properly sized pressure relief valve is installed in 

the relief valve opening provided.

The  pressure  rating  of  the  relief  valve  should  be  equal  to  or  less 

than the rated pressure capacity of any component in the system 

including the boiler. Should the valve need to be replaced, call the 

toll free phone number listed on the back of this manual for further 

technical assistance.

A  discharge  pipe  from  the  relief  valve  should  terminate  at  an 

adequate  floor  drain.  Do  not  thread,  plug,  or  cap  the  end  of  the 

drain line.

The Discharge Pipe:

•  Shall not be smaller in size than the outlet pipe size of the valve, 

or have any reducing couplings or other restrictions.

•  Shall not be plugged or blocked.

•  Shall not be exposed to freezing temperatures.

•  Shall be of material listed for hot water distribution.

•  Shall  be  installed  so  as  to  allow  complete  drainage  of  both  the 

relief valve and the discharge pipe.

•  Must terminate a maximum of six inches above a floor drain or 

external to the building. In cold climates, it is recommended that 

the discharge pipe be terminated at an adequate drain inside the 

building.

•  Shall not have any valve or other obstruction between the relief 

valve and the drain.

Once the boiler is installed and filled with water and the system is 

pressurized, manually test the operation of the pressure relief valve. 

See the maintenance section of this manual for instructions.

water lIne connectIons

The boiler may be installed by itself, or with a separate storage tank, on 

both single and two-temperature systems. When used with a separate 

storage tank, the circulation may be either by gravity or by means of 

a circulating pump. When a circulating pump is used it is important to 

note that the flow rate should be slow so that there will be a minimum 

of turbulence inside the heater.

InstallatIon

Summary of Contents for NW 37-670

Page 1: ...ep for future reference COMMERCIAL ELECTRIC BOILERS Thank you for buying this energy efficient boiler from us We appreciate your confidence in our products MODELS NW 37 670 INSTALLATION OPERATION SERV...

Page 2: ...the type of hazard what can happen if you do not follow the safety message and how to avoid the risk of injury The California Safe Drinking Water and Toxic Enforcement Act requires the Governor of Ca...

Page 3: ...ay also cause erratic control system operation on ELECTRONIC CONTROL models This boiler must be connected to a grounded metal permanent wiring system or an equipment grounding conductor must be run wi...

Page 4: ...hen standing in water When replacing fuses always use the correct size for the circuit See page 12 through 14 The principal components of the heater are identified on page 8 The model and rating plate...

Page 5: ...4 4 4 3 3 3 3 1 1 1 1 NW NW NW NW NW 96 96 96 96 96 330K 390K 420K 450K 480K 36 36 36 36 36 38 38 38 38 38 16 16 16 16 16 69 1 2 69 1 2 69 1 2 69 1 2 69 1 2 17 17 17 17 17 1 1 2 1 1 2 1 1 2 1 1 2 1 1...

Page 6: ...1800K 1860K 1980K 2100K 66 66 66 66 56 56 56 56 28 28 28 28 90 1 2 90 1 2 90 1 2 90 1 2 25 1 2 25 1 2 25 1 2 25 1 2 2 1 2 2 1 2 2 1 2 2 1 2 30 30 30 30 33 33 33 33 7 3 4 7 3 4 7 3 4 7 3 4 8 8 8 8 2 2...

Page 7: ...60 2 90 4 90 6 60 1501 1668 1299 1443 648 720 792 864 542 602 663 723 NW NW NW NW NW NW NW 220 220 220 220 220 220 220 780K 840K 900K 960K 1020K 1080K 1140K 2 662 140 2 866 920 3 071 700 3 276 480 3 4...

Page 8: ...8 FEATURES AND COMPONENTS ACTUAL CONFIGURATION MAY VARY...

Page 9: ...the area adjacent to the boiler or to lower floors of the structure 3 The discharge opening of the temperature and pressure relief valve should always be piped to an open drain 4 Close to the point o...

Page 10: ...ut being certain the boiler is filled with water and a properly sized pressure relief valve is installed in the relief valve opening provided The pressure rating of the relief valve should be equal to...

Page 11: ...ng increase in water pressure due to thermal expansion Thermal expansion can cause premature tank failure leakage This type of failure is not covered under the limited warranty Thermal expansion can a...

Page 12: ...th this computation the next higher standard rating or setting should be selected Boiler Circuits The boiler s electrical components are pictured and identified on page 8 The model and rating plate il...

Page 13: ...TH THERMOSTAT NOTE S 1 IF A MANUAL RESET HLMT IS USED THE SECOND AUTO RESET HLMT SWITCH IS NOT USED STD WIRING OPTIONAL OR FIELD WIRING AS REQ D NOTE S 1 IF A MANUAL RESET HLMT IS USED THE SECOND AUTO...

Page 14: ...ON LIGHT 1 OFF ON 2200 2 OFF ON 135 3 OFF ON 4 20MA 4 OFF ON 0 10VDC 5 DS PROP 6 PROG UN 7 OFF VER 8 SEC MN 1 DELAY 1 2 DELAY 2 3 DELAY 3 4 1 5 2 6 4 7 5 8 16 THE ABOVE DIP SWITCH SETTINGS ARE AN EXAM...

Page 15: ...y be in the control circuit in addition to the automatic high limit previously described The control has an adjustable range of 110 F to 290 F and activates and locks on a temperature increase When th...

Page 16: ...proximate time to burn relationship for normal adult skin Water Temperature Time to Produce 2nd 3rd Degree Burns on Adult Skin 180 F 82 C 160 F 82 C 150 F 82 C 140 F 82 C 130 F 82 C 120 F 82 C 80 F 82...

Page 17: ...dential pipe dope thread cutting oil solder flux dirt and other foreign materials breakdown to form gas This is indicated by a continuing need for purging even through the system is closed 2 Pump seal...

Page 18: ...switch serving the boiler is in the ON position The pilot switch es on the cabinet front should be on In some installations the boiler electrical service may be limited by the power company or boiler...

Page 19: ...ges for forwarding the new tank or replacement part from the nearest distributor and returning the claimed defective tank or part to such distributor c All cost necessary or incidental for any materia...

Page 20: ...A DIVISION OF A O SMITH CORPORATION RENTON WASHINGTON Technical Support 800 527 1953 Parts Department 800 433 2515 www hotwater com...

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