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Water heaters for use with Natural and L.P.G.
GWH 425 HN
Flow Modulated with Electronic Ignition
Suitable for heating potable water only - Not approved for space heating purposes
(Intended for variable flow applications with steady cold water inlet temperatures)
GWH-425-HN-N
GWH-425-HN-L
Warning: If the information in this manual is not What to do if you smell gas
followed exactly, a fire or explosion may result
• Close gas valve. Open windows.
causing property damage, personal injury or death.
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TABLE OF CONTENTS Specifications ................................................................ Page 3 WARNING: Improper installation, Rules for safe operation .............................................. Page 5 adjustment, alteration, service or maintenance can cause Locating the Heater.....................................................Page 5 injury or property damage. Refer to this manual. For Combustion Air Requirements ................................... Page 6 assistance or additional
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Principle of Operation: 425 HN LP and 425 HN NG Specifications When a hot water faucet is opened, the water flow through the heater causes the gas valve to open. At the same time the hydro-generator activates the electronics which sends Gas Input max.: 117,000 Btu/hr a spark to the pilot. The flame sensor confirms the pilot has min.: 28,000 Btu/hr been lighted and allows the first two burners to come on. The flame sensor confirms correct activation and all burners Water Connection ½” Thread fit
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FRONT VIEW SIDE VIEW MINIMUM INSTALLATION CLEARANCES FROM COMBUSTIBLE AND NON COMBUSTIBLE MATERIALS FOR ALCOVE OR CLOSET INSTALLATIONS MODEL 425 HN TOP (A) 12" FRONT (B) 4" BACK 0" SIDES 4" FLOOR (C) 12" VENT DIAMETER 5" MODEL 425HN 4 6 720 607 026
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The heater may still operate even when improperly vented. GENERAL RULES TO FOLLOW It will, however, be less efficient and could eventually damage FOR SAFE OPERATION the heater. It could even result in human sickness or death due to oxygen deprivation and carbon monoxide poisoning. 1. You should follow these instructions when you install your Follow the guidelines below: heater. In the United States: The installation must conform with local codes or, in the absence of local codes, the 1. Place y
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Appliances located in confined spaces: WARNING: Flammable materials, gasoline, The confined space must be provided with two permanent pressurized containers, or any other items or articles openings, one commencing within 12 inches of the top and that are potentially fire hazards must NOT be placed on one commencing within 12 inches of the bottom of the or adjacent to the heater. The appliance area must be enclosure. Each opening must have a minimum free area of kept free of all combustible mate
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MINIMUM 6 FEET (1.8M) plasterboard, can cause failure of mounting. appliance. The heater should never be common vented In earthquake-prone zones, CEC recommends that installers with a mechanically vented appliance. Single wall vent use a large washer and lag screw through the existing holes pipe is not recommended, if used consult the National used to hang the heater to affix the upper third of the heater Fuel Gas Code. to the mounting board. To affix the lower third of the heater, Horizontally
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MASONRY CHIMNEY: Masonry chimneys shall be built and minimum vertical chimney length should be no less than 5 installed in accordance with NFPS 211 or local codes. A ft (1.5 m); the termination point should extend at least 3 minimum 5” diameter gas vent pipe (metal double wall Type feet (0.9 m) above where the chimney meets the roofline B), or an approved clay flue liner or a listed chimney lining and at least 2 feet (0.6 m) higher than any vertical wall or system must be used when venting into
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draft diverter outlet must be connected to an unobstructed NOTE: The gas pressures specified below refer to vent of the same size, or larger. pressures taken at the pressure tap on the gas inlet pipe In Canada, CAN/CGA-B149 Installation Code for detailed just above the regulator (See Fig 5). These readings requirements should be taken while the heater is operating at full input In U.S.A., ANSI Z223.1 - NFPA 54, National Fuel Gas — i.e. maximum water flow with the temperature dial Code for detai
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GAS PIPING, CONNECTIONS and Gas Regulator Before connecting the gas supply, check the rating plate on the right side of the front cover to be sure that the heater is rated for the same gas to which it will be connected. In the United States: The installation must conform with local codes or, in the absence of local codes, the National Fuel Gas Code ANSI Z223.1/NFPA 54. In Canada: The Installation should conform with CGA B149 INSTALLATION CODES and /or local installation codes. GAS LINE SIZING Th
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WATER CONNECTIONS Install the heater centrally in the building if possible and make hot water piping runs as short as possible When facing the heater, the cold water inlet will be on the right and the hot water outlet on the left. Although water piping throughout the building may be other than copper, copper or galvanized piping should be used when connecting to the heaters ½” male NPT flex connectors (follow local codes if more stringent). Plastics or other PEX type plumbing line materials are
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The position you select on the temperature adjustment knob LIGHTING AND OPERATING INSTRUCTIONS will depend on the temperature of the incoming water (50°F 1. STOP! Read the safety information above on this label. is average in the U.S.). In warm weather regions where the 2. The gas valve must be shut off by putting the ON/OFF incoming cold water is generally warmer, or during the hot switch to position “ ”. Wait five (5) minutes to clear weather months in some other areas a midway setting on out
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To clean the pilot burner and/ or the pilot orifice : Turn MAINTENANCE AND SERVICE off the gas to the unit. Set the On/Off switch to Off (position REVIEW MAINTENANCE TABLE ON THE BACK OF THIS ). Remove the cover of the heater. To do so, pull off MANUAL. the temperature adjustment knob and unscrew and remove Approximately once a year, the 425 HN should be checked the plastic collar. Pull main cover out toward you and lift up and cleaned. To remove the front cover, first remove the and out. The pi
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Problems are stated in upper case, bold face. Most common SPARK APPEARS AT PILOT WHEN HOT WATER TAP causes for the problems follow in order of likelihood. The TURNED ON, BUT PILOT AND BURNERS WILL NOT IGNITE suggested solutions require that the cover be taken off. To do this, remove incandescent particle tray, pull off the 1. Air in the Gas Line temperature adjustment knob and unscrew and remove the Normally this is a problem at time of initial installation, after plastic collar. Pull main cover
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PILOT LIGHTS BUT BURNERS WILL NOT COME ON 5. Flue gas safety device tripped Ventilate the room and operate the appliance 10 minutes 1. Confirm water valve assembly is working properly. later. Provide more combustion air to the room and/or inspect See Water Valve under MAINTENANCE AND SERVICE. and correct venting system. Afterwards, if it happens again, contact your service person. 2. Confirm the flame sensor is in its proper position and clean, lightly wipe clean if dirty. See Fig. 10 WATER IS T
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HOT WATER TEMPERATURE FLUCTUATES / UNIT DEACTIVATED 1. Unbalanced pressure in waterlines The added restriction caused by the 425 HN in the hot water system can result in uneven pressures between the cold and the hot. In such cases when mixing cold water at the tap, the lower hot water pressure may be overpowered by a much higher cold water pressure, which may cause the 425 HN burners to shut down. Make sure faucet aerators or shower heads are free of minerals. Do not add any flow restrictor to t
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Fig. 14 - Diagram of 425 HN 1 3 2 4 5 6 7 8 10 9 12 11 6 720 606 804-10.1AL 1. Heat exchanger 7. on/off switch 2. Pilot assembly 8. LED operation indicator 3. Burner manifold gas 9. Water valve pressure test nipple 10. Temperature adjustment selector 4. Main gas burner 11. Gas inlet gas pressure test nipple 5. Pilot gas tubing 12. Hose 6. LED failure indicator 6 720 607 026 17
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Fig. 15 - INTERIOR COMPONENTS DIAGRAM AND PARTS LIST 18 6 720 607 026
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Fig. 15 INTERIOR COMPONENTS DIAGRAM AND PARTS LIST 425 HN 1 Cover 8 705 421 752 2 Temperature adjustment knob 8 702 000 111 3 Temperature adjustment collar 8 700 403 008 4 Draft diverter 8 705 505 354 5 Heat exchanger 8 705 406 235 7 Main burner 8 708 120 298 NG 7 Main burner 8 708 120 296 LP 8 Burner assembly washer 8 710 103 060 9 Throttle disc 8 700 100 174 LP 10 Pilot burner 8 708 105 491 LP 10 Pilot burner 8 718 105 051 NG 11 Pilot electrode 8 708 107 006 12 Pilot orifice 8 708 200 069 NG 1
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Fig. 16 - Flow chart of 425 HN 20 6 720 607 026
