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Bosch Pro Tankless GWH-450-ES Series, Manual, Page: 8 / 32

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Bosch Pro Tankless GWH-450-ES Series Manual Download Page 8

6 720 607 915

8

Appliance details

2.7

Applications

Introduction

The application designs provided in this manual are general guides to be used when installing this recirculating water 
heater. Additional application designs are available from Bosch Water Heating.

Instantaneous water heater (direct tank load version)

Fig. 6

Caution: 

the water heater which will be

used to supply potable water shall not
be connected to any heating system or
component(s) previously used with a
nonpotable water heating appliance.

Summary of Contents for Pro Tankless GWH-450-ES Series

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 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 smell gas Close gas valve Open wind...

Page 2: ...e or use gasoline or other flammable combustible or corrosive vapors and liquids in the vicinity of this or any other appliance Warning Carefully plan where you install the heater Correct combustion air supply and flue pipe installation are very important If a gas appliance is not installed correctly fatal accidents can result from lack of air carbon monoxide poisoning or fire Warning Exhaust gas ...

Page 3: ...erence received including interference that may cause undesired operation Fig 1 Warning The recirculating water heater must be disconnected 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 party responsible for compliance could void the user s authority to...

Page 4: ...l Selection range 100 F 40 C 140 F 60 C Gas Requirement Gas connection inches Inlet gas pressure under operation with a high hot water flow rate Propane 11 14 water column Natural Gas 5 5 8 water column To measure Gas Pressure see Measuring Gas Pressure chapter 3 8 Venting 3 AL 29 4C Stainless Steel exhaust See chapter 3 6 for Venting Water Hot water connection inches Cold water connection inches ...

Page 5: ...Before installing the unit be certain you have the correct heater for your type of Gas Propane or Natural Gas Identification labels are found on the shipping box and on the rating plate which is located on the right side panel of the cover To remove front cover B Loosen the two Philips head screws located as shown in fig 2 Fig 2 Screws B Pull control panel outwards and then pull it downwards Fig 3...

Page 6: ...Keep water heater area clear and free from combustibles and flammable liquids Do not locate the heater over any material which might burn B 7 Correct gas pressure is critical for the optimum operation of this water heater Gas piping must be sized to provide the required pressure at the maximum output of the water heater while all the other gas appliances are in operation Check with your local gas ...

Page 7: ...ight side only 2 Exhaust adapter with CO2 measuring point 3 Front cover 4 On Off button 5 Reset button 6 ECO flow thermostat 7 LED ON warning light blinks when in lock out 8 Hot water thermostat 9 Mounting plate Fig 5 Minimum clearances Model GWH 450 ES TOP 12 FRONT B 4 BACK 0 SIDES BOTTOM 12 VENT DIAMETER 3 Table 1 Minimum clearances ...

Page 8: ...alling this recirculating water heater Additional application designs are available from Bosch Water Heating Instantaneous water heater direct tank load version Fig 6 Caution the water heater which will be used to supply potable water shall not be connected to any heating system or component s previously used with a nonpotable water heating appliance ...

Page 9: ... AL29 4C vent pipe vent type rated for Category III appliances must be used when exhaust venting this appliance See 3 6 Venting 3 4 Mounting installation B Secure the wall mounting bracket provided with the water heater to a wall surface If wall is a stud wall sheathed with plasterboard it is recommended that support board s either 1x4 s or 1 2 minimum plywood first be attached across a pair of st...

Page 10: ...confined spaces in buildings of conventional frame masonry or metal construction infiltration air is normally adequate to provide air for combustion Appliances located in confined spaces The confined space must be provided with two per manent openings one commencing within 12 inches 304 8mm of the top and one commencing within 12 inches 304 8mm of the bottom of the enclosure Each opening must have...

Page 11: ... Note reduce 6 ft for each 90 elbow used after the first one reduce 3 ft for each 45 elbow Exhaust vent conditions Warning Do not reduce the vent exhaust and combustion pipe sizes and do not common vent with any other vented appliance or stove Warning Failure to vent the exhaust gases to the outside with sealed stainless steel vent pipe AL29 4C may result in dangerous flue gases filling the space ...

Page 12: ...ssory 8 705 504 142 to the top of the unit position 1 using the 4 screws and gasket provided and fully insert 3 stainless steel vent pipe into the accessory and tighten the clamp position 2 B Place first gasket into fresh air intake B Place air deflector B Place second gasket and then the restrictor on top of deflector use table 4 for the correct side B Attach the combustion air inlet accessory 8 ...

Page 13: ...18 28 47 28 50 50 50 75 55 75 100 60 Table 4 Restrictors i Described example was done taking as example Fig 15 Part 3 feet 1 foot 90 45 out in Totalequivalent length Comb gas steel Number of parts 10 1 1 48 0 Equivalent length part 3 0 1 0 6 0 3 0 12 0 Totalequivalent length part 30 0 6 0 12 0 Comb gas steel Number of parts 6 1 1 15 0 Equivalent length part 1 5 0 5 3 0 1 5 3 0 Totalequivalent leng...

Page 14: ... of four 90 degree elbows are permitted in both the exhaust and combustion air vent lengths Open combustion installation SINGLE PIPE SYSTEM Not recommended in cold climate areas see Chapter 3 5 Fig 17 Exhaust vent pipe 39 ft 12 m The exhaust vent system must vent directly to the outside of the building and an adequate amount of indoor combustion air must be provided for this installation See chapt...

Page 15: ...metal shielding 12 in C From any internal corner 12 in D Above ground or snow pack 12 in Above a paved sidewalk 7 ft E From an opposing wall or structure facing the termination 24 in From the relief valve of a Ip gas regulator 36 in F From a terminator facing a terminator 48 in G Vertically between two exhaust vent terminators on the same wall 60 in H Horizontally between two exhaust vent terminat...

Page 16: ...gas fittings Bubbles are a sign of a leak A combustible gas detector may also be used to detect for leaks GAS LINE SIZING The gas supply piping should be sized according to the applicable code for a maximum draw of 120 000 BTUH Measure the length of gas supply line and use the tables in Fig 21 or the gas line manufacturer s sizing tables to determine the pipe diameter necessary to accommodate the ...

Page 17: ...in Thousands of BTU per Hour of Undiluted Liquefied Petroleum Gases at 11 inches Water Column Inlet Pressure Based on a Pressure Drop of 0 5 Inch Water Column Source National Fuel Gas Code NFPA 54 ANSI Z223 1 No Additional Allowance is necessary for an ordinary number of fittings FOR LP GAS Maximum Capacity of Pipe in Thousands of BTU per Hour of Undiluted Petroleum Gases at 11 inches Water Column...

Page 18: ...s appliances on same gas piping system at maximum output B Record static pressure reading in table 7 Operating pressure test B Press On Off button to turn heater On B After 10 seconds press and hold the reset button B Rotate the recirculating water temperature selector left knob to the minimum and then to maximum B Release the reset button and the display should show blinking B Place a demand for ...

Page 19: ...n on a private well system with the use of a pressure tank the lowest pressure range setting recommended is 30 50 psi 2 07 and 3 45bar Connecting the pressure relief valve PRV A listed pressure relief valve supplied with the heater must be installed at the time of installation No valve is to be placed between the PRV and the water heater No reducing coupling or other restriction may be installed i...

Page 20: ...nce if any part has been under water Immediately call a qualified service technician to inspect the appliance and to replace any part of the control system and any gas control which has been under water 4 2 Startup instructions B 1 STOP Read the previous safety information B 2 The gas valve must be shut off by putting the ON OFF switch to position OFF Wait five 5 minutes to clear out any gas If yo...

Page 21: ...wer adjustment Note only when using the 12 kOhm DHW thermistor B Connect thermistor to blue wire with terminal block Power can be set from 70 to 100 of full power in thermostat Fig 28 Fig 28 4 6 Freeze prevention B Do not disconnect the electric supply B Do not install in unheated areas which can experience freezing temperatures B Do NOT use non potable additives like glycol Freeze Prevention A ki...

Page 22: ...nstructions 4 7 Electrical diagram Fig 29 Electrical scheme 11 Control electrode 12 Spark plug 13 Gas valve 14 Fan 15 Temperature limiter 16 Differential pressure switch 17 Primary circuit temperature sensor 18 LED 19 Flow switch ...

Page 23: ... Reference diagrams on pages 27 and 28 Venting system Unclip 4 access clip to inspect and clean burner assembly Manual operation of the pressure relief valve to insure correct operation As indicated by reduced flow flush the heat exchanger with a descaling solution if mineral build up is evident Scale build up will shorten the life of the water heater descale heat exchanger thoroughly and repeat a...

Page 24: ...r chamber Check electronic unit Orange LED 140 F flashing Shut down because of low voltage Check power supply Check electronic unit Orange LED 100 F 140 F flashing Shut down by pressure switch Check chimney fresh air tube and combustion gas tube Check ventilator Venturi silicone tubes Check pressure switch short opened Check cables electronic Orange LED 110 F 140 F flashing NTC defect no function ...

Page 25: ...ly Check the complete ignition system Orange LED 125 F Ionisation signal detected with the burner stopped Check the sensor electrode Check the control unit Orange LED 140 F Gas valve is not being detected Check the electrical connections to the primary NTC sensor and the pri mary NTC sensor itself Orange LED 110 F 140 F Primary NTC temperature sensor dis connected or in short circuit Check the ele...

Page 26: ...6 720 607 915 26 GWH 450 ES Functional scheme 7 GWH 450 ES Functional scheme Fig 30 Functional scheme ...

Page 27: ...ght side only 2 Exhaust adapter with CO2 measuring point 3 Front cover 4 On Off button 5 Reset button 6 ECO flow selector 7 LED ON warning light blinks when appliance in lock out 8 Hot water temperature selector 10 LED to display error codes and temperatures 13 Gas valve 14 Fan 19 Flow switch 20 Main burner 21 Heat exchanger 22 Holding bracket 23 Hot water pipe 24 Cold water pipe ...

Page 28: ...6 720 607 915 28 Interior components diagram and parts list 8 2 Components diagram Fig 32 Components Diagram ...

Page 29: ... 701 309 158 0 18 Screw 10x 8 743 401 019 0 19 Cage nut 8 703 309 001 0 20 Screw M 5 0X20 DIN 7985 2 910 642 162 0 GROUP 3 1 Main burner 8 708 120 622 0 2 Screw 10x 8 703 404 089 0 Table 11 3 Screw 10x 8 703 401 069 0 4 Screw M4 x 12 phillips 10x 2 910 952 122 0 5 Nozzle 125 10x 8 708 202 116 0 6 Nozzle 120 10x 8 708 202 124 0 7 Nozzle 120 10x 8 708 202 124 0 8 Crossignition bridge 8 711 304 337 0...

Page 30: ... limiters They will give you the same comfort level while saving water B Define the temperature you want in the appliance or with the remote control 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 ...

Page 31: ...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 32: ...ial 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 __________ Installing Company _____________________________________________ Installer name _____________________________________________ Address __________________________...

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