Bosch Pro Tankless GWH-425-HNO-L, Instructions For Use Manual

Page 1: ... 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 is approved only for seasonal use Installation must be performed 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 ...

Page 2: ...8 6 4 Hot water temp fluctuates from hot to cold 18 6 5 Water is too hot 19 6 6 Water is not hot enough 19 7 Interior components diagram and parts list 20 7 1 Interior components 20 7 2 Components diagram 21 7 3 Parts list 22 8 Protecting the environment 23 9 Fifteen Year Limited Warranty 24 1 Warning For your safety Do not store or use gasoline or other flammable combustible or corrosive vapors a...

Page 3: ...ot reach your gas supplier call the fire department Installation and service must be performed by a qualified installer service agency or the gas supplier Fig 1 Fig 2 Warning The heater must be isolated from the gas supply piping system during any pressure testing of that system at test pressures equal to or more than 0 5 psig Caution Any changes or modifications not expressly approved by the part...

Page 4: ...um input 117 000 Btu h 34 3 kW Efficiency in Recovery efficiency 80 Min Output 28 000 Btu h 8 2 kW Gas Requirement Gas connection inches Inlet gas pressure under maximum operation Propane 10 5 14 water column Natural Gas 5 7 14 water column To measure Gas Pressure see Measuring Gas Pressure chapter 3 6 Water Hot water connection inches Cold water connection inches Water valve material Polymer PPS ...

Page 5: ...se 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 ANSI Z223 1 NFPA 54 In Canada The Installation should conform with CGA B149 1 2 INSTALLATION CODES and or local installation codes B 2 Carefully plan where you install the heater Proper clearances must be followed B 3 The appli...

Page 6: ... 148 6 Appliance details 2 5 Dimensions and installation clearances Fig 3 Dimensions Fig 4 Minimum clearances Model GWH 425 HNO TOP A 3 ft FRONT B 4 ft BACK 0 SIDES 4 ft BOTTOM C 1 ft Table 1 Minimum clearances ...

Page 7: ... ever anticipated Danger If the temperature drops below 32 F freeze damage to the water heater itself must be prevented by turning off the power to the heater then disconnecting the plumbing conne ctions as well as removing the drain plug and introducing short bursts of compressed air 20 40 psi through the heater s connections This will remove the residual water in the horizontal pipes and water v...

Page 8: ...ently used hot tap note clearances in chapter 3 3 B If the unit is to be installed on a combustible surface use the enclosed heat shield see Fig 5 Danger The top of the kit will get hot due to the flue gases Install away from children Ref Description Min distances A Directly below or from an opening operable windows doors and any fresh air openings 4 ft B C D From any adjacent wall or tall shruber...

Page 9: ...nting screws Use mounting template for proper screw location B Locate head of screw in the key hole of the top mounting bracket Vent Safety System The GWH 425 HNO will shut down if the intake or exhaust louvers on the vent cap are blocked for any reason see troubleshooting section on page 18 ...

Page 10: ...icated 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 specified below refer to pressures taken at the pressure tap on the gas inlet pipe just above the regulator See chapter 3 6 for measu...

Page 11: ... 30 40 50 60 70 80 90 100 125 150 175 200 1 4 0 364 32 22 18 15 14 12 11 11 10 9 8 8 7 6 3 8 0 493 72 49 40 34 30 27 25 23 22 21 18 17 15 14 1 2 0 622 132 92 73 63 56 50 46 43 40 38 34 31 28 26 3 4 0 824 278 190 152 130 115 105 96 90 84 79 72 64 59 55 1 1 049 520 350 285 245 215 195 180 170 160 150 130 120 110 100 1 1 4 1 380 1050 730 590 500 440 400 370 350 320 305 275 250 225 210 1 1 2 1 610 160...

Page 12: ... 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 below freezing temperatures are ever anticipated where the heater is located insulation material is required and must be capable of protecting the piping fr...

Page 13: ...med Warning This heater must be electrically grounded in accordance with the most recent edition of the National Electrical Code NFPA 70 In Canada all electrical wiring to the heater should be in accordance with local codes and the Canadian Electrical Code CSA C22 1 Part 1 Do not rely on the gas or water piping to ground the metal parts of the heater Warning The heater is equipped with freeze prev...

Page 14: ...you do not smell gas go to the next step B 7 Set the switch located behind the sliding viewer window on the front panel strip to the ON position In this position the water heater is ready to use Note On first time initial installation existence of air in the gas supply line and in the water line may cause some ignition delay In that case repeatedly open and close the hot water tap in order to rest...

Page 15: ...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 one flame position The hottest position is the three flame position all the way to the right Knob position clockwise counter clockwise Degree rise 90 F 45 F Activati...

Page 16: ...ructions 4 5 Electrical diagram Fig 12 Electrical scheme 1 Burner electrovalve 2 Gas control valve 3 Pilot electrovalve 4 Flame sensor 5 Pilot electrode 6 Hydro generator 7 Electronic control box 8 Temperature limiter 9 on off switch ...

Page 17: ...rs The parts list and instruction can be found on our website at www boschpro com 5 3 Pilot Inspecting pilot The pilot should burn with a clean sharp blue flame The flame should fully envelope the bend of the flame sensor rod If it does not clean the pilot assembly per procedure below Cleaning pilot assembly Disconnect the flame sensor rod cable and the igniter cable by pulling gently down Remove ...

Page 18: ...hot water tap off and then turn back on Repeat this procedure until pilot lights and the heater fires It is not unusual to have to cycle the heater 20 30 times before the heater fires the first time B 9 Check to make sure the manual gas shut off valve is in the open position Have licensed gas technician or service person check the presence of gas at the gas pressure measuring tap on the left side ...

Page 19: ...e summer than in the winter Use the slide control to lower output temperature as outlined in chapter 4 4 B 3 Contact you service person if water temperature does not lower per procedure outlined in chapter 4 4 6 6 Water is not hot enough B 1 Adjust the temperature per chapter 4 4 B 2 Shut off installer supplied cold water supply valve if none installed install before proceeding Open all hot water ...

Page 20: ...s list 7 1 Interior components Fig 13 Functional scheme 1 Heat exchanger 2 Pilot assembly 3 Burner manifold gas pressure test nipple 4 Main gas burner 5 Pilot gas tubing 6 on off switch 7 Water valve 8 Gas control slide 9 Electronic control box 10 Temperature adjustment selector 1 4 5 6 10 7 8 9 2 3 ...

Page 21: ...8 716 473 148 Interior components diagram and parts list 21 7 2 Components diagram Fig 14 Components Diagram ...

Page 22: ...8 708 200 312 0 LP 18 Pilot gas pipe 8 700 707 370 0 19 Washer 8 700 103 173 0 20 Gas valve 8 707 021 109 0 NG 20 Gas valve 8 707 021 108 0 LP 21 Diaphragm switch 8 708 504 021 0 NG 21 Diaphragm switch 8 708 504 049 0 LP 22 Pilot valve 8 708 501 249 0 23 Servovalve 8 708 501 250 0 24 Gas regulator 8 716 487 043 LP 24 Gas regulator 8 716 487 044 NG 25 Water valve 8 707 002 708 0 26 Water valve cove...

Page 23: ...ripping Repair any leaking tap B Define the temperature 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 ...

Page 24: ...r 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 service removal or re installation of the original water heater or a replaced...

Page 25: ...alling Company _____________________________________________ Installer name _____________________________________________ Address _____________________________________________ Phone _____________________________________________ See Chapter 3 6 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 Replac...