Bosch GWH-425-HN-N Manual

Bosch GWH-425-HN-N Manual

Flow modulated with hydro-generated ignition
Hide thumbs Also See for GWH-425-HN-N:

Advertisement

Quick Links

Water heaters for use with Natural and L.P.G.
GWH 425 HN
Flow Modulated with Hydro-generated 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
followed exactly, a fire or explosion may result
causing property damage, personal injury or death.
Do not store or use gasoline or other flammable
vapor and liquids in the vicinity of this or any other
appliance.
Improper
installation,
service or maintenance can cause injury or
property damage. Refer to this manual. For
assistance or additional information consult a
qualified installer, service agency or the gas
supplier.
In the Commonwealth of Massachusetts this
product must be installed by a licensed plumber or
gas fitter.
Upon completion of the installation, these
instructions should be handed to the user of the
appliance for future reference.
adjustment,
alteration,
What to do if you smell gas
• Close gas valve. Open windows.
• Do not try to light any appliance.
• Do not touch any electrical switch; do not use any
phone in your building.
• Immediately call your gas supplier from a neighbor's
phone. Follow the gas supplier's instructions.
• If you cannot reach your gas supplier, call the fire
department.
• Installation and service must be performed by a
qualified installer, service agency or the gas supplier.

Advertisement

Table of Contents
loading

Summary of Contents for Bosch GWH-425-HN-N

  • Page 1 Flow Modulated with Hydro-generated 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...
  • Page 2 Index Index Warning Warning Warning: The heater must be isolated Appliance details from the gas supply piping system GWH 425 HN specifications (Technical data) during any pressure testing of that Unpacking the GWH 425 HN heater system at test pressures equal to or General rules to follow for safe operation more than 0.5 psig.
  • Page 3: Appliance Details

    Appliance details Appliance details GWH 425 HN specifications Dimensions (Technical data) • Depth (in): 10.5” (265 mm) • Width (in): 18.25” (460 mm) Approved in US/Canada • Height (in): 36.75” (936 mm) Capacity • Weight: 64 pounds (29 kg). GWH 425 HN: 4.36 GPM Gas types Maximum output Natural Gas.
  • Page 4: General Rules To Follow For Safe Operation

    Please complete and return the enclosed product has been underwater. registration card. BOSCH is constantly improving its The GWH 425 HN is not approved or designed for: products, therefore specifications are • Manufactured (mobile) homes, RV's or boats subject to change without prior notice.
  • Page 5: Dimensions And Installation Clearances

    Appliance details Dimensions and installation clearances Fig. 3 Dimensions in Inches and (mm) Heat exchanger Burner Dimensions Temperature control inches (mm) Water valve Gas connection GWH 425 HN Igniter unit Output control 16.73” (425) LED indicator for burner status 25.75” (655) Front cover Hole for fixing to wall 13.15”...
  • Page 6: Installation Instructions

    NO DAMAGE this heater properly, please contact a locally licensed to adjacent areas. plumber or gas technician. Please contact Bosch Water Heating with any Heater placement and clearances questions. The GWH 425 HN is design certified for installation on Proper location for installing your a combustible wall (see 3.4 Mounting installation)
  • Page 7: Mounting Heater

    Installation instructions B Hang heater on two L shaped hooks (See Fig. 8). Mounting Heater Warning: before starting installation: B check that there are no loose parts inside the appliance B ensure that gas pipe, gas valve, and burner have no damage and are properly fitted.
  • Page 8: Combustion Air Requirements

    Installation instructions Combustion air requirements Fuel Gas Code for complete information. In buildings of tight construction all air should be taken from outside. The Protankless water heater holds cold water in its copper heat exchanger and water valve when not in use. Venting Because of this, any cold air that comes down through the unit's vent pipe is capable of freezing these...
  • Page 9 Installation instructions B All gas vent sections must be secured to each other with sheet metal screws and be properly supported. 5” X 6” ADAPTOR USED ON HIGH Horizontal runs: ALTITUDE Any gas vent section that is greater than 45 degrees from the vertical is considered horizontal.
  • Page 10 Installation instructions Masonry chimney LOWEST DISCHARGE Masonry chimneys shall be built and installed in LISTED VENT CAP OPENING accordance with NFPS 211 or local codes. A minimum 5" diameter gas vent pipe (metal double wall Type B), or an approved clay flue liner or a listed chimney lining H (minimum) height from roof to lowest system must be used when venting into a naturally...
  • Page 11: Gas Piping & Connections

    Installation instructions B Attach the appliance regulator to the inlet gas pipe. Gas piping & connections B The minimum diameter required for any appliance Before connecting the gas supply, check the rating connector used is ¾” NPT. plate on the right side of the heater to be sure that the B National Fuel Gas Code requires that a sediment heater is rated for the same gas to which it will be trap (drip leg) be installed on gas appliances not so...
  • Page 12 Installation instructions FOR NATURAL GAS Maximum Capacity of pipe in Cubic Feet of Gas per Hour for Gas Pressure of 0.5 Psig or less and a Pressure drop of 0.3 in Water Column (0.75mbar).(Based on a 0.60 Specific Gravity Gas) Btu numbers given in thousands. Copper tubing is prohibited for use with Natural Gas in the Commonwealth of Massachusetts and not recommended elsewhere.
  • Page 13: Measuring Gas Pressure

    Installation instructions Measuring gas pressure Although water piping throughout your structure may be other than copper, we recommend that copper piping Connecting manometer or suitably rated stainless steel flex line piping be used for at least three feet before and after the heater (follow B Shut off gas.
  • Page 14: Recirculation Application

    Attempted forceful repair may result in a fire or Contact Bosch Water Heating if further instruction is explosion. needed. D. Do not use this appliance if any part has been under water.
  • Page 15: Lighting Instructions

    Operation instructions Lighting instructions To turn off appliance B 1. STOP! Read the previous safety information. B Set the ON/OFF switch to the position OFF B 2. The gas valve must be shut off by putting the ON/ OFF switch to position OFF .
  • Page 16: Power Adjustment

    Operation instructions Setting the water temperature Power adjustment The GWH 425 HN has a gas control that modulates Less power. burner input in response to flow. Its purpose is to Lower water temperature. ensure that the hot water temperature will remain steady, although the water flow demand might vary.
  • Page 17: Maintenance And Service

    If the set screws are seized, STOP and call recommended maintenance may result Bosch tech support before proceeding. Forcing and in complete failure of the unit over time. snapping seized set screws may cause irrevocable The warranty does not cover failures damage to the water valve and gas valve assemblies.
  • Page 18: Main Burners

    Maintenance and service Main burners 12. Run solution through the heat exchanger until the solution returning to the descaling reservoir comes out The main burner flames should be blue, with a more clear. (Changing to a fresh solution may be necessary intense blue cone in the center core.
  • Page 19: Troubleshooting

    Visit www.boschpro.com to purchase 3. Close installer supplied cold water shut off valve (if replacement part, or call Bosch Water Heating at 866- none installed, install before proceeding). Open all hot 330-2730 for replacement part if still under warranty.
  • Page 20: Pilot Light, But Burners Will Not Come On

    1.6V AC. If voltage is proper, pilot electro valve is defective. If voltage is not proper, electronic control box is defective. Visit www.boschpro.com to purchase replacement part, or call Bosch Water Heating at 866-330-2730 for replacement part if still under warranty. Pilot light, but burners will not come on.
  • Page 21: Hot Water Temperature Fluctuates At Tap

    Troubleshooting need for cold water mixed by turning the power pressure for the home should be 30psi or greater. For adjustment knob clockwise for lower hot water installations on a private well system with the use of a temperatures. See chapter 4.4 and 4.5 for details in pressure tank, the lowest pressure range setting lowering temperature.
  • Page 22 Troubleshooting 5. If water is still too hot, consult service bulletins on 6.10 Low hot water pressure www.boschpro.com to lower outlet temperatures 1. Confirm adequate flow rate through the unit. With further. cold supply shut off to the unit, disconnect hot outlet 6.
  • Page 23: Protecting The Environment

    Protecting the environment accordance with specifications in the installation manual. A gas pressure reading is needed to proceed 7 Protecting the environment further. Contact your original installer or a local certified gas technician to obtain this reading. See chapter 3.9. 3.
  • Page 24: Interior Components And Diagram Parts List

    Interior components and diagram parts list Interior components and diagram parts list Interior components Fig. 26 Functional scheme Heat exchanger Flexible hot outlet Main gas burner Output control Electronic control box Pilot gas tubing Temperature adjustment selector on/off button Water valve Gas connection 6 720 608 036...
  • Page 25: Components Diagram

    Interior components and diagram parts list Components diagram 6720608036-05.1 JF Fig. 27 Components Diagram 6 720 608 036...
  • Page 26: Parts List

    Interior components and diagram parts list Parts list Item Description Reference Front cover 8 705 431 247 0 Shield 8 705 506 816 0 Trade mark badge 8 701 103 135 0 Power adjustment knob 8 702 000 297 0 Temp.
  • Page 27: Fifteen Year Limited Warranty

    BOSCH heaters warranted Manufacturer (BOSCH) through BBT North America. Note: the water heater must be free of BBT North America (BBTNA) will furnish a replacement damaging scale deposits and not subject...
  • Page 28 Installation manual should be left with the owner after the installation is tested and completed BBT NORTH AMERICA Bosch Group BBT Termotecnologia Portugal S.A. Bosch Water Heating 340 Mad River Park Estrada de Cacia Waitsfield, VT 05673 3801 - 856 Aveiro - PORTUGAL...

This manual is also suitable for:

Gwh 425 hnGwh-425-hn-l

Table of Contents