Instruction/ maintenance manual of the product GWH 425 HN Bosch Appliances
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Water heat ers for u se with Natural an d L.P.G. GWH 425 HN Flow Mo dulat ed wit h Elec t ronic Ignit ion Suit able for heat ing pot able wat er o nly - Not approve d for spac e heat ing pu rposes (Intend ed for vari able fl ow applicatio ns with stea dy cold wa ter inlet t emperatu res) GWH- 425-HN -N GWH- 425-HN -L 6 720 607 026 US (04.
2 6 720 607 026 WARNING : Improper installation, adjustment , alterat ion, service or maint enance c an c ause injury or property damage. Refer to this manual. For assistance or additional information consult a qualified installer, service agency or the gas supplier.
3 6 720 607 026 Principle of Operation: 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 a spark to the pilot. The flame sensor confirms the pilot has been lighted and allows the first two burners to come on.
4 6 720 607 026 M I N I M U M I N S T ALLA TI O N C LE ARAN C E S F R O M C O M B U STI B LE AN D N O N CO M B U S TI B LE MA TE R IALS F O R AL C OVE O R C L O S ET I N ST ALLA TI O N S FRONT VIEW SI.
5 6 720 607 026 G E N E R AL R U LE S T O FOLL OW FOR SAF E OP E R A TION 1. Y ou should follow these instructions when you install your heater . In the United States : The installation must conform with local codes or, in the absence of local codes , the National Fuel Gas Code AN S I Z223.
6 6 720 607 026 WARNING: Flammable materials, gasoline, pressurized containers, or any other items or articles that are potent ially fire hazards must NO T be placed on or adjacent to t he heat er . The appliance area must be kept free of all combustible materials, gasoline and other flammable vapors and liquids.
7 6 720 607 026 VENTING V ent pipe connect ion . WARNING: Do not reduce the vent pipe size. See Fig. 4 for high altitude installations The heater must be vented to the outside following all local ordinances and specifications for installing a gas appliance vent or c himney.
8 6 720 607 026 T o check t he draft : Close all doors and windows to the outside. T urn on all appliances that force air out of the building. These include all exhaust/ventilation fans, furnaces, clothes dryers, wood burning stoves, etc. Open all doors between the 425 HN and these other appliances.
9 6 720 607 026 GAS CONNECTIONS NO TE: The 425 HN is supplied wit h a gas pressure regulator that must be installed on the heater before attaching the gas supply line. See fig. 5. Failure to install the gas regulator as shown in figure 5 will be a violation of CSA cert ificat ion of t he unit .
10 6 720 607 026 Nominal Iron P ipe Black Iron Pipe Size , Lengt h of Pipe, Feet Inches 10 20 30 40 50 60 70 80 90 100 125 150 1/2 275 189 152 129 114 103 96 89 83 78 69 63 3/4 567 693 315 267 237 2 1.
11 6 720 607 026 OPER A T ING INST RUC T IONS Before proceeding with the operation of the heater make sure that the system is filled with water . Open the cold water inlet supply to the heater fully .
12 6 720 607 026 The position you select on the temperature adjustment knob will depend on the temperature of the incoming water (50 °F is average in the U.
13 6 720 607 026 Fig. 1 0 - Charact eristic Pilot Flame (Pilot assembly shown without pilot hood) MAINTENANCE AND SERVICE RE VIEW MAINTENA NCE T ABLE ON THE BA CK OF TH IS MANUAL. Approximately once a year , the 425 H N should be chec ked and cleaned.
14 6 720 607 026 Problems are stated in upper case, bold face. Most common causes for the problems follow in order of likelihood. The suggested solutions require that the cover be taken off. T o do this, remove incandescent particle tray , pull off the temperature adjustment knob and unscrew and remove the plastic collar .
15 6 720 607 026 Fig. 1 3 - Electric al wiring diagram 5 . Flue gas safety device tripped V entilate the room and operate the appliance 1 0 minutes later . Provide more combustion air to the room and/or inspect and correct venting system. Afterwards, if it happens again, contact your service person.
16 6 720 607 026 HO T WA TE R TE M PE R A TU R E FLUCTUA TE S / U N IT DEAC TIV A TED 1 . Unbalanced pressure in waterlines T he added restriction caused by the 425 H N in the hot water system can result in uneven pressures between the cold and the hot.
17 6 720 607 026 Fig . 1 4 - Diagram of 425 H N 1 . Heat exchanger 2. Pilot assembly 3. Burner manifold gas pressure test nipple 4. Main gas burner 5. Pilot gas tubing 6. LED failure indicator 7 . on/off switch 8. LED operation indicator 9. W ater valve 1 0 .
18 6 720 607 026 Fig. 15 - I NTE R IOR C OM P ON E NTS DIAGR AM AN D P ARTS LIST.
19 6 720 607 026 Fig. 1 5 INTERIOR COMPONENTS DIAGRAM AN D P ARTS LIST 425 HN 1 Cover 8 705 421 752 2 Tem perature adj ustm ent knob 8 702 000 111 3 Tem perature adj ustm ent collar 8 700 403 008 4 Dr.
20 6 720 607 026 Fig . 1 6 - Flow chart of 425 H N.
21 6 720 607 026 Service Labor Costs This warranty does not cover any labor costs associated with service, removal or re-installation of part(s). All such costs must be borne by the Purchaser.
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VU L C ANO T ermodomésticos S.A . Estrada de Cacia 380 1 - 8 56 Aveiro - PO RTU GAL Recycled paper © 20 04 C ontrolled Energy C orporation, W aitsfield, V T all rights reserved Replacement Parts available from North American Distributor CONTROLL E D E N ER G Y C OR P .
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