Bosch GWH-425-HN-L Specifications

GWH 425 HNFlow Modulated with Hydro-generated IgnitionSuitable for heating potable water only - Not approved for space heating purposes (Intended for

6 720 608 03610Installation instructionsMounting heater.The heater must be mounted on a wall usingappropriate anchoring materials. If wall

6 720 608 036Installation instructions113.6 Gas piping & connectionsBefore connecting the gas supply, check the ratingplate on the right si

6 720 608 03612Installation instructionsFOR NATURAL GASMaximum Capacity of pipe in Cubic Feet of Gas per Hour for Gas Pressure of 0.5 Psig or less and

6 720 608 036Installation instructions133.7 Measuring gas pressureConnecting manometerB Shut off gas.B Remove front cover and locate inlet gas

6 720 608 03614Operation instructions3.9 Recirculation applicationSince recirculation through the heater is not allowed,the following drawing

6 720 608 036Operation instructions154.2 Lighting instructionsB 1. STOP! Read the previous safety information.B 2. The gas valve must be shut off by p

6 720 608 03616Operation instructionsB Turning the flow control knob clockwise restricts water flow. This provides higher temperature because the wa

6 720 608 036Maintenance and service175 Maintenance and service5.1 Maintenance intervalsThe GWH 425 HN requires periodic maintenance. Thetime maintena

6 720 608 03618Maintenance and service5.4 Main burnersThe main burner flames should be blue, with a moreintense blue cone in the center

6 720 608 036Troubleshooting196 Troubleshooting6.1 IntroductionMany of the questions customers ask regardingoperation of this unit can be answer

6 720 608 0362IndexIndex1 Warning 22 Appliance details 32.1 GWH 425 HN specifications (Technical data) 32.2 Unpacking the GWH 425 HN heater 42.3 G

6 720 608 03620Troubleshooting– e. Verify that gas shut off valves are open. Gas must be supplied to heater.– f. Measure gas pressure at inlet tap wit

6 720 608 036Troubleshooting21or service person for help correcting a plumbingcrossover.3. The minimum water pressure required is 30psi. Forins

6 720 608 03622Troubleshootingthe water heater should be cleaned and inspected. Seechapter 5.2.5. If the water has a high mineral content, th

6 720 608 036Protecting the environment237 Protecting the environment PackingThe packing box may be fully recycled as confirmed bythe recycling symbol

6 720 608 03624Interior components and diagram parts list8 Interior components and diagram parts list8.1 Interior componentsFig. 27 Functional scheme4

6 720 608 036Interior components and diagram parts list258.2 Components diagramFig. 28 Components Diagram125040101186721224235313336394520191514131617

6 720 608 03626Interior components and diagram parts list8.3 Parts listItem Description Reference1 Front cover 8 705 431 247 02 Shield 8 705 506 816 0

6 720 608 036Fifteen Year Limited Warranty279 Fifteen Year Limited WarrantyGeneralBOSCH PRO heaters are warranted by theManufacturer (BOSCH) t

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6 720 608 036Appliance details32 Appliance details2.1 GWH 425 HN specifications (Technical data)Approved in US/CanadaCapacityGWH 425 HN: 4.36 GPMMinim

6 720 608 0364Appliance details2.2 Unpacking the GWH 425 HN heaterBefore installing the unit, be certain you have thecorrect heater for your type of G

6 720 608 036Appliance details52.4 Dimensions and installation clearancesFig. 3 Dimensions in Inches and (mm)4 Heat exchanger5 Burner10 Flow control k

6 720 608 0366Installation instructions3 Installation instructions3.1 IntroductionPlease follow these instructions. Failure to followinstruction

6 720 608 036Installation instructions7B An approved gas vent connector must be attached tothe top of the water heater and rise vertically at least12&

6 720 608 0368Installation instructionsMasonry chimneyMasonry chimneys shall be built and installed inaccordance with NFPS 211 or local codes.

6 720 608 036Installation instructions93.4 Combustion air requirementsThe Protankless water heater holds cold water in itscopper heat exchange