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GWH 345/450 ESR

Temperature Modulated with Electronic Ignition

Suitable for heating recirculating potable water

GWH-345/450-ESR-N - Natural Gas
GWH-345/450-ESR-L - Liquefied Petroleum (LP) Gas

6 72

0 607

 909

 U

S

 (20

08.

07)

 JS

Warning: 

If the information in this manual is not

followed exactly, a fire or explosion may result
causing property damage, personal injury or death.
Do not store or use gasoline or other flammable
vapor and liquids in the vicinity of this or any other
appliance.

Improper installation, adjustment, alteration,
service or maintenance can cause 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 smell gas

• Close gas valve. Open windows and doors, and

evacuate the building.

• Do not try to operate any appliance.

• Do not touch any electrical switch; do not use any

phone in your building

• Immediately call your gas supplier from a neighbor’s

phone. Follow the gas supplier’s instructions.

• If you cannot reach your gas supplier, call the fire 

department.

• Installation and service must be performed by a 

qualified installer, service agency or the gas supplier.

Summary of Contents for GWH 345 ESR-L

Page 1: ... 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 windows and doors ...

Page 2: ...rior components diagram and parts list 37 9 1 Interior components 37 9 2 Components diagram 38 9 3 Parts list 39 10 Protecting the environment 40 11 Ten Year Limited Warranty 41 1 Warning For your safety Do not store 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 Corre...

Page 3: ... adjustment Warning If a water heater is installed in a closed water supply system such as one having a backflow preventer in the cold water supply line means shall be provided to control thermal expansion Contact the water supplier or local plumbing inspector on how to control this situation Warning Keeping appliance area clear and free from combustible materials gasoline and other flammable vapo...

Page 4: ...n efficiency 82 GWH450 Combustion efficiency 81 Min Output GWH345 23 900 Btu h 7 kW GWH450 35 500 Btu h 10 4 kW Temperature Control Selection range 113 F 45 C 194 F 90 C Gas Requirement Gas connection inches Inlet gas pressure under operation with a high hot water flow rate Propane 11 13 water column Natural Gas 5 5 10 5 water column To measure gas pressure see Measuring Gas Pressure chapter 3 8 V...

Page 5: ... 450 ESR LP Ø47 50 55 60 Do not lose this manual Please complete and return the enclosed product registration card 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 Philip...

Page 6: ...he appliance and its gas connection must be leak tested before placing the appliance in operation 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 testing at pressures in excess of Psig 3 5 kPa 6 Keep water heater area clear and free from combustibles and flammable liquids Do not locate ...

Page 7: ...haust adapter with CO2 measuring point 3 Front cover 4 On Off button 5 Reset button 6 Recirculating water temperature selector 7 LED ON warning light blinks when in error lock out 8 Domestic hot water temperature selector 9 Mounting bracket Fig 6 Minimum clearances Model GWH 345 450 ESR TOP 12 FRONT B 4 BACK 0 SIDES BOTTOM 12 Table 1 Minimum clearances ...

Page 8: ...taneous water heater direct tank load design Fig 7 Fig 8 Service position to access water and electric connections 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 Caution Do not overpump the heater Maximum 5 gpm water flow permitted through the heater Note maxim...

Page 9: ... a water condi tioner or softener GWH 345 ESR 0 feet of head 10 feet of head 20 feet of head 30 feet of head 40 feet of head 50 feet of head 0 GPM 1 GPM 2 GPM 3 GPM 4 GPM 5 GPM 6 GPM water flow rate Inlet pressure GWH 450 ESR 0 feet of head 10 feet of head 20 feet of head 30 feet of head 40 feet of head 50 feet of head 0 GPM 1 GPM 2 GPM 3 GPM 4 GPM 5 GPM 6 GPM water flow rate Inlet pressure Descri...

Page 10: ...eel AL29 4C vent pipe 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 heater to a wall surface If wall is a stud wall sheathed with plaster or drywall it is recommended that support board s either 1x4 s or 1 2 minimum plywood first be attached across a pair of studs The...

Page 11: ...g 12 If a single pipe installation is utilized follow guidelines below for providing adequate combustion air for the water heater as well as any other appliances that may consume air in the space Always follow local codes if they are more stringent This Installation Manual specifies the minimum exhaust vent length and the amount of combustion air required for this unit When all requirements are fo...

Page 12: ...if all air is taken from the outside by direct openings or vertical ducts Or the space must be provided with one permanent opening or duct that is within 12 inches of the ceiling of the enclosure This opening must have a minimum free area of one square inch per 3000 Btu hr if all air is taken from the outside by a direct opening or vertical duct Louvers grills and screens have a blocking effect If...

Page 13: ... The last horizontal run including the termination must be sloped to the outside 1 4 per foot to prevent rain from entering the venting system Fig 13 Minimum exhaust vent length Danger Do not combination vent this appliance with any other appliance Warning Do not reduce the vent exhaust and combustion pipe sizes Warning Failure to vent the exhaust gases to the outside with sealed stainless steel v...

Page 14: ...ch the flue gas exhaust accessory 8 705 504 142 to the top of the unit position 1 using the 4 screws and gasket provided B Insert 3 single wall stainless steel vent pipe into exhaust vent adapter 1 5 and tighten the clamp position 2 Note Failure to fully insert and tighten vent pipe may cause flue gas leakage or condensate damage that is not covered under the manufacturer s warranty Fig 15 Exhaust...

Page 15: ... sections 1 1 straight section Total length 31 2 90 elbow 1 GWH 450 ESR termination Intake 5 4 straight sections 2 1 straight sections Total length 22 3 90 elbows 1 GWH 450 ESR termination Example Note Do not count the first elbow used Using table 8 the following restrictors would be required GWH 450 ESR NG restrictor 55 GWH 450 ESR LP restrictor 55 Exhaust 1 Straight section length __ x 1 ____ 2 ...

Page 16: ...ace gasket deflector gasket and inlet air restrictor on the air inlet opening lining up screw holes as seen in Fig 16 Fig 16 Mounting sequence a Gasket b Deflector c Restrictor d Adaptor B Attach the combustion air inlet accessory 8 705 504 141 to the top of the unit position 3 using the 4 screws provided B Install 3 combustion air pipe over the air inlet accessory Fig 17 Combustion air inlet acce...

Page 17: ... condensate drain installation 3 6 4 Room sealed installation Twin pipe Although it is permitted to draw combustion air from inside the recommended method is to provide combustion air through a 3 pipe from the outside See Chapter 3 5 for more direction on combustion air To reduce pressure differentials between the exhaust and combustion air intake it is required that both terminators exit on the s...

Page 18: ...emaining in the chimney The vent terminator must extend at least 3 feet 0 9 m above where the chimney meets the roofline and at least 2 feet 0 6 m higher than any vertical wall or similar obstruction within 10 feet 3 1 m The top of the chimney must be sealed to prevent rain water or other elements from entering the chimney Exterior Masonry Chimney Refer to the National Fuel Gas Code and consult a ...

Page 19: ...erior of the building at a minimum height of eight 8 feet above grade directly in line with the exhaust vent terminal for the horizontally vented gas fueled heating appliance or equipment The sign shall read in print size no less than one half 1 2 inch in size GAS VENT DIRECTLY BELOW KEEP CLEAR OF ALL OBSTRUCTIONS 4 INSPECTION The state or local gas inspector of the side wall horizontally vented g...

Page 20: ...n Below a gutter sanitary pipework or eaves protected by 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 wa...

Page 21: ...15 feet above the meter regula tor assembly 3 feet 91 cm within a height 15 feet above the meter regulator assembly O Clearance to a mechanical air supply inlet 6 feet 1 83 m 3 feet 91 cm above if within 10 feet 3 m 6 feet 1 83 m 3 feet 91 cm above if within 10 feet 3 m P Clearance above paved sidewalk or paved direway located on public property 7 feet 2 13 m 3 7 feet 2 13 m 3 7 feet 2 13 m Q Clea...

Page 22: ...lation NOTE If appliance uses room air do not place any other combustion appliance in the same space to avoid depressurizing of the building and winter freeze up Use room sealed operation instead FIRESTOP SUPPORT HANGER STRAPS ELBOW TO DRAIN DISPOSE OF CONDENSATE ACCORDING TO LOCAL CODES APPLIANCE RAIN CAP STORM COLLAR FLASHING 4 MIN AIR SPACE 6720607915 14 6JS HORIZONTAL RUN 1 4 RISE FT FROM HEAT...

Page 23: ...ed 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 GWH450ESR or 96 000BTUH GWH345ESR Measure the length of gas supply line and use the tables in Fig 28 or the gas line manufacturer s sizing tables to determine the pipe diameter necessary to accommodate the BTU demand of the unit If there are more gas draw...

Page 24: ...2 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 1600 1100 890 760 670 610 560 530 490 460 410 380 350 320 2...

Page 25: ...maximum output B Record operating pressure reading in Table 11 B Press On Off button to turn heater Off and exit Diagnostic Mode Operating gas pressures lower than 5 5 W C for nat ural gas or 11 W C for LP will result in improper oper ation and must be corrected See Chapter 3 7 for gas line sizing requirements Manifold pressure test B To confirm manifold pressure connect manometer to upper tapping...

Page 26: ...32 Install the heater centrally in the build ing if possible and make piping runs as short as pos sible Fig 32 B The use of unions when connecting both water pipes to the inlet and outlet connections is recommended This will facilitate any necessary servicing B Although water piping throughout the building may be other than copper we recommend that copper or suitably rated stainless steel flex lin...

Page 27: ...ension on a T fitting can be sweated to the hot water line Support all piping Fig 33 Plumbing Connections and Pressure Relief Valve 3 11 Electrical connections The GWH 345 450 ESR requires an electrical power supply from a 120VAC 60Hz circuit and must be properly grounded A means for switching off the 120VAC power supply must be provided The heater is wired as shown in the wiring diagram chapter 4...

Page 28: ...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 3 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 you smell gas STOP Follow the safety in...

Page 29: ...ed Aquastat set temperature on Aquastat control left knob should be in maximum position To activate and use the appliance domestic temperature dial a 12 kOhm thermistor is required part number 8 714 500 034 See 2 6 Page 8 for wiring diagram B Connect the 12kOhm thermistor blue wire to the DHW NTC terminal block Install the sensor in the tank well Hot water temperature can be set from 50 F to 158 F...

Page 30: ...e 13 Junction box wiring of tank pump 14 Fan 15 Temperature limiter ECO 16 Differential pressure switch 17 TT connection under low voltage cover plastic 18 Domestic hot water temperature sensor 12kOhm only under low voltage cover plastic 19 LED 20 Fuse 3 15 NOTICE Except for the fuse there are no serviceable parts inside the electronics ...

Page 31: ... exchanger thoroughly and repeat annually depending on mineral content of ground water 5 1 Diagnostic mode The Diagnostic Mode provides diagnostic information to the technician with a variety of real time parameters See Table 16 for the parameters and their respective meaning Accessing the Diagnostic mode B Switch on the equipment B Press and hold the reset button B Rotate the hot water temperatur...

Page 32: ... used 07 Selected DHW temperature only if 12kOhm thermistor used Displays the domestic hot water temperature as selected by the user only if 12kOhm external thermistor used 08 Not used displayed values have no relevance 09 Pressure switch 00 Open pressure switch fan is off or there is no exhaust gas flow 01 Closed pressure switch fan is on or there is exhaust gas flow 10 Temperature limiter 01 tem...

Page 33: ...re and then check to ensure the CO2 is within the limits in table 17 i If the appliance is not powered off and then back on again it returns to normal working conditions after 5 minutes Appliance CO2 GWH 345 ESR N 6 8 7 2 GWH 345 ESR L 7 5 8 0 GWH 450 ESR N 6 5 7 0 GWH 450 ESR L 7 0 7 5 Table 17 CO2 levels at max input Warning do not exceed 9 5 W C for LP or 4 0 W C for NG at maximum input Always ...

Page 34: ...ts corrosion 3 Use diagnostic mode 12 to verify if gas valve is closed 4 Check control unit1 E0 Shut down because of low voltage 1 Check for adequate power supply 2 Check control unit for visible damage1 F0 Internal error in the control unit 1 Check control unit connections and wiring 2 Replace control unit C4 Fan not working 1 No power to fan check for 120 volts at fan 2 Check wire connections C6...

Page 35: ... circulation air inside installation bad heat transfer 1 Check for air in system purge if detected 2 Check circulators for proper oper ation 3 Check heat exchanger for block age or scale deposits 4 Check gas type injectors gas valve 5 Verify heater is not in service mode No heating function No heat demand by the thermostat thermostat set too low other defect 1 Check thermostat position 2 Check con...

Page 36: ...6 720 607 909 36 GWH 345 450 ESR Functional scheme 8 GWH 345 450 ESR Functional scheme Fig 39 Functional scheme APS Air Pressure Switch ...

Page 37: ...right side only 2 Exhaust adapter with CO2 measuring point 3 Front cover 4 On Off button 5 Reset button 6 Recirculation water temperature selector 7 LED ON warning light blinks when in lock out 8 Domestic hot water temperature selector 12 Gas valve 20 Junction box 21 Centrifugal blower 22 Main burner 23 Heat exchanger 24 Holding bracket 25 Outlet water pipe 26 Inlet water pipe ...

Page 38: ...6 720 607 909 38 Interior components diagram and parts list 9 2 Components diagram Fig 41 Components Diagram ...

Page 39: ...9 158 12 Screw 8 743 401 019 13 Cage nut 8 703 309 001 14 Screw M 5 0X20 DIN 7985 2 910 642 162 15 Clip 8 716 102 607 GROUP 3 1 Main burner LP GWH345ESR 8 708 120 625 1 Main burner NG GWH345ESR 8 708 120 624 1 Main burner LP GWH450ESR 8 708 120 623 1 Main burner NG GWH450ESR 8 708 120 622 Table 19 2 Screw 8 703 404 089 3 Screw 8 703 401 069 4 Screw M4 x 12 phillips 2 910 952 122 9 Washer 8 701 003...

Page 40: ...y authorities for information about the disposal of recyclable products Saving water resources B Make sure you close all the taps after any use Avoid leaving the taps dripping Repair any leaking tap B Whenever possible use taps with built in water flow limiters They will give you the same comfort level while saving water B Set the water temperature to the desired temperature or slightly higher Hot...

Page 41: ... highly mineralized unsoftened water supply All Other Parts If any other part fails within one 1 year after original installation and operation Bosch Thermotechnology Corp will furnish a replacement part free of charge 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 Additiona...

Page 42: ...6 720 607 909 42 Ten Year Limited Warranty ...

Page 43: ...6 720 607 909 Ten Year Limited Warranty 43 ...

Page 44: ...e on right side panel Gas Pressure reading Static__________ Operating__________ CO2 reading __________ Air restrictor size __________ Building Water Pressure __________ Range if on Well system __________ Installing Company _____________________________________________ Installer name _____________________________________________ Address _____________________________________________ Phone __________...

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