Bosch Model GWH 425 User Manual Download

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Recycled paper

BBT

NORTH AMERICA CORPORATION,

VULCANO Termodomésticos S.A.

Estrada de Cacia

3801 - 856 Aveiro - PORTUGAL

BBT

NORTH AMERICA

Bosch Group

Bosch Water Heating

340 Mad River Park

Waitsfield, VT 05673

Phone 866-330-2730

Fax 802-496-6924

www.boschpro.com

[email protected]

Installer Checklist, to be performed by installer upon installation

Serial Number

___ ___ ___ ___ ___ ___ ___ ___

(8 digit serial number is located on rating plate on right side panel)

Gas Pressure Reading*

Static__________

Operating__________

Building Water Pressure

__________ Range if on Well system __________

Average Winter Temperature

__________

Average Summer Temperature

__________

Installing Company

_____________________________________________

Installer name

_____________________________________________

Address

_____________________________________________

Phone

_____________________________________________

* See Chapter 3.8 and gas pressure table (to be filled out by installer)

Installation manual should be left with the owner after the installation is tested and completed

Summary of Contents for Model GWH 425

Page 1: ...e 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 What to do if you s...

Page 2: ...burners 18 5 5 Vent assembly 18 5 6 Mineral scale build up 18 6 Troubleshooting 19 6 1 Introduction 19 6 2 Pilot does not light 19 6 3 Pilot lights but goes out when button is released 19 6 4 Pilot goes out during or after hot water use 19 6 5 Burners do not light with water flow 20 6 6 Hot water temperature fluctuates at tap 20 6 7 Water is too hot 21 6 8 Water is not hot enough 21 6 9 Burners ig...

Page 3: ...Venting Natural Draft Vent diameter inches 5 Minimum height feet 6 with no elbows Vertical termination Sidewall termination only with AQ4 power vent kit Water Hot water connection inches NPT Cold water connection inches NPT Water valve material Polymer PPS Polypropylene Sulfid Minimum water flow 0 5 gallon minute 1 9 l m Minimum recommended water pressure 30 PSI 2 07 bar Connections Bottom of heat...

Page 4: ...onal Fuel Gas Code ANSI Z223 1 NFPA 54 In Canada The Installation should conform with CGA B149 1 2 INSTALLATION CODES and or local installation codes 2 Carefully plan where you install the heater Proper clearances must be followed 3 The appliance must be isolated from the gas supply piping system by closing its individual manual gas shutoff valve not supplied with heater during any pressure testin...

Page 5: ...Hole for fixing to wall 38 Exhaust pipe to wall 39 Draught diverter with flue gas monitor 40 Gas valve 49 Observation window 102 Piezo Fig 4 Minimum clearances Model GWH 425 TOP A 12 inches 306 mm FRONT B 4 inches 100 mm BACK 0 inches SIDES 4 inches 100 mm BOTTOM C 12 inches 306 mm Dimensions inches mm GWH 425 PN A 16 73 425 B 25 75 655 C 13 15 334 D 5 11 130 E 21 25 540 F 2 55 65 G 1 18 30 H 3 4 ...

Page 6: ...aterial For installations in an alcove or closet maintain the minimum clearances to combustible and non combustible materials listed below See also Fig 4 A Top 12 inches 306 mm B Front 4 inches 100 mm C Back 0 inches D Sides 4 inches 100 mm E Bottom 12 inches 306 mm Warning The water in this water heater is cold and always remains cold except for the times that hot water is being used DO NOT INSTA...

Page 7: ...d with plasterboard it is recommended that support board s either 1x4 s or 1 2 minimum plywood first be attached across a pair of studs and then the heater should be attached to the support boards see Fig 7 B Secure the two included L shaped hooks to wall studs or support board 13 1 4 apart See Fig 7 B Hang heater on two L shaped hooks See Fig 8 Fig 6 Remove front cover Fig 7 Support board Fig 8 S...

Page 8: ... per 1000 Btu per hour of the combined rating of all appliances installed in the space That would be 5850 cubic feet for the BOSCH PRO GWH 425 PN alone b Installations in structures that have been tightly constructed air infiltration rate of 0 40 ACH or less must be provided for combustion air per the National Fuel Gas Code Consult a HVAC specialist if your air infiltration rate is questionable Ap...

Page 9: ... must be secured to each other with sheet metal screws and be properly supported Horizontal runs Any gas vent section that is greater than 45 degrees from the vertical is considered horizontal Horizontal sections must slope upwards at least inch for every foot of its horizontal length and be properly supported Keep the horizontal section short and avoid too many elbows The maximum horizontal run a...

Page 10: ...ipe check local codes for clarification The lining material must be listed for use only with naturally drafting draft hood equipped gas appliances Follow manufactures instructions for installation of listed lining material You may not vent any other fuel burning appliances into any free space remaining in the chimney The minimum vertical gas vent length within the masonry chimney should be no less...

Page 11: ...HIGH ALTITUDE INSTALLATION The pressure regulator provided with the heater is adjusted to deliver the proper gas pressure as indicated on the rating plate and in the manual for altitude up to 2000 feet 660 meters above sea level On appliances being installed above 2000 ft 660 meters elevation the inlet gas pressure should be set at installation to the value shown below Note The gas pressures speci...

Page 12: ...ure Drop of 0 5 Inch Water Column EHD Equivalent Hydraulic Diameter The greater the value of EHD the greater the gas capacity of the tubing Tube size inches EHD 10 20 30 40 50 60 1 2 18 EHD 82 58 47 41 37 34 3 4 23 EHD 161 116 96 83 75 68 1 30 EHD 330 231 188 162 144 131 1 1 4 37 EHD 639 456 374 325 292 267 Length of Flexible Corrugated Stainless Steel Tubing CSST Feet Tube size inches EHD 10 20 3...

Page 13: ...ter connections damage can occur to the internal water valve from heating of the pipe Plastics or other PEX type plumbing line materials are not recommended for connecting directly to the water heater Keep water inlet and outlet pipes to no less than 12 7mm diameter to allow the full flow capacity It is recommended that all water piping below the heater be properly insulated to avoid heat loss If ...

Page 14: ...uctions exactly B What to do if you smell gas WHAT TO DO IF YOU SMELL GAS B Close gas valve Open windows B Do not try to light any appliance B Do not touch any electric switch do not use any phone in your building B Immediately call your gas supplier from a neighbors phone Follow the gas supplier s instructions B If you cannot reach your gas supplier call the fire department C Use only your hand t...

Page 15: ...own for at least 15 seconds with pilot burning before releasing When the gas valve button is released the pilot should continue to burn If the gas valve button does not pop out when released stop and immediately call your service technician or gas supplier If pilot does not stay lit repeat all steps If pilot will not stay lit after several tries slide the gas valve button all the way to the left a...

Page 16: ...ning the knob clockwise will raise the temperature and lower the activation rate Gas control slide button The gas control slide button adjusts temperature by adjusting how much gas is allowed to flow to the burners As the slide is adjusted to the left the output temperature will lower with the lowest setting being the small flame position Fig 24 The hottest position is the highest flame position a...

Page 17: ... the water valve Loosen the two set screws at the bottom of the water valve where it connects to the gas valve If the set screws are seized STOP and call Bosch tech support before proceeding Forcing and snapping seized set screws may cause irrevocable damage to the water valve and gas valve assemblies Remove the water valve by pulling it to the right Separate the two halves of the water valve by r...

Page 18: ...ain water from the unit s heat exchanger by disconnecting inlet and outlet water connections 5 Connect the line A from the outlet of the circulating pump installer supplied to the inlet water fitting on the water heater 6 Using another line B connect to the water outlet fitting on the water heater Route the other end of this line into a descaling reservoir 7 Using a 3rd line C from the descaling r...

Page 19: ...tch models with Powervents only and the electromagnet See parts diagram for locations Clean sensor connections with light sandpaper if corrosion is evident The electromagnet connection is 5mm nut from the thermocouple which screws into a larger 17mm nut Tighten both nuts snugly but do not over tighten 5 Pilot flame should be blue in color and completely engulfing the tip of the thermocouple If not...

Page 20: ...th it in order to attain a useable hot water temperature The addition of too much cold will overpower and slow the flow within the tankless water heater decreasing it below activation point which shuts off the burners The end result is nothing but cold water coming out of the outlet Reduce the need for cold water mix by setting the gas slide control button towards the single flame position for low...

Page 21: ... person for help in correcting a plumbing crossover 5 Inspect the water path outside of the heater for obstructions Make sure all outlets i e showerheads faucet aerators and whole house filters are clear of debris Also the water heater s inlet filter screen should be inspected and cleaned see chapter 5 2 6 The water valve may be dirty prohibiting it from fully opening the gas valve This part needs...

Page 22: ...pressure may be inadequate resulting in improper combustion Ensure gas pressure is in accordance with manufacturer s specifications see chapter 3 6 A gas pressure reading is needed to proceed further Contact your original installer or a licensed gas technician to obtain this reading 3 For proper combustion at high elevations the inlet gas pressure should be set at installation to the value shown i...

Page 23: ...rature you want This way you have the precise water flow needed mixing cold water to regulate temperature will increase the water flow with consequent waste of water For increased safety shut off the appliance from the main water supply if your are staying away from home for a considerable time At below freezing temperatures disconnect the plumbing connections to the heater and allow the heater to...

Page 24: ...8 Interior components and diagram parts list 8 1 Interior components Fig 28 Functional scheme 4 Heat exchanger 5 Burner 10 Temperature adjustment selector 11 Water valve 20 Gas connection 22 Flexible hot outlet 26 Gas control slide 30 Pilot gas tubing 102 Piezo ...

Page 25: ...diagram parts list 25 8 2 Components diagram Fig 29 Components Diagram 43 50 49 32 48 46 45 28 29 30 31 25 17 18 19 20 21 23 26 24 27 33 34 35 13 36 37 22 38 39 40 41 42 44 47 8 9 11 12 13 14 15 16 10 6 4 5 51 1 2 3 7 6720608126 02 1 JF 52 ...

Page 26: ... 0 22 Poppet valve head 3 LP 8 708 500 359 0 23 Electromagnet 8 707 201 028 0 24 Electromagnet cap 8 703 305 283 0 25 Valve operation housing 8 708 008 069 0 26 Guide plate 8 701 000 380 0 27 Gas pressure regulator LP 8 707 406 083 0 27 Gas pressure regulator NG 8 707 406 084 0 28 Water valve 8 707 006 344 0 29 Watervalve pushrod 10x 8 703 204 051 0 30 Diaphragm L 8 700 503 084 0 31 Inlet water co...

Page 27: ...supplying the replacement part s BBTNA will provide ground service delivery for these parts Expedited or upgraded shipping will be charged to the customer 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 Additionally this warranty does not cover any labor costs associated with...

Page 28: ...mber is located on rating plate on right side panel Gas Pressure Reading Static__________ Operating__________ Building Water Pressure __________ Range if on Well system __________ Average Winter Temperature __________ Average Summer Temperature __________ Installing Company _____________________________________________ Installer name _____________________________________________ Address __________...

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