Bosch 940 ESO Instruction Manual

Suitable for heating potable water and space heating
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940 ESO
For Outdoor Installations Only
Temperature Modulated with Electronic Ignition
Suitable for heating potable water and space heating
(Intended for variable flow applications)
940 ESO - Natural Gas
940 ESO - Liquefied Petroleum (LP) Gas
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
vapors and liquids in the vicinity of this or any other
appliance.
Improper
installation,
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.
6720644956-00.1V
adjustment,
alteration,
What to do if you smell gas
• Close gas valve. Open windows.
• Do not try to light 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.

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Summary of Contents for Bosch 940 ESO

  • Page 1 (Intended for variable flow applications) 6720644956-00.1V 940 ESO - Natural Gas 940 ESO - Liquefied Petroleum (LP) Gas Warning: If the information in this manual is not What to do if you smell gas followed exactly, a fire or explosion may result •...
  • Page 2: Table Of Contents

    Electrical diagram Space heating applications Measuring gas pressure Sensor resistance charts Electrical connections Electrical power supply GWH 940 ESO Functional scheme Position of the fuses in control unit Interior components diagram and parts list 16.1 Interior components 16.2 Components diagram...
  • Page 3: Warning

    Warning Warning Warning: The maximum inlet gas pressure must not exceed the value For your safety specified by the manufacturer and the minimum value listed is for the purpose Do not store or use gasoline or other flammable, of input adjustment. combustible or corrosive vapors and liquids in the vicinity of this or any other appliance.
  • Page 4 Warning Warning: A 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. Warning: Installation in mobile homes shall conform to Title 24 CFR, Part 3280 and/or CAN/CSA Z240 MH Se- ries, Mobile Homes.
  • Page 5: Appliance Details

    • Recess box (7736500043) • Minimum recommended water pressure: 30 PSI • Pressure relief valve (FWL-2). (2.07 bar). BOSCH is constantly improving its • Minimum well pressure 40 psi, see page 21. products, therefore specifications are • Connections: subject to change without prior notice.
  • Page 6: Unpacking The Heater

    Please complete and return the enclosed product registration card. The 940 ESO is not approved or designed for: • Recreational vehicle (RV) or boat installations. • Use above 8000 ft A.S.L. altitude (see page 30). • Outdoor installation without installation of Outdoor kit (BTOK) or Recess Box (7 736 500 043).
  • Page 7: General Rules To Follow For Safe Operation

    Appliance details To remove front cover General rules to follow for safe operation B Loosen the two Phillips head screws located on bottom rear of cover (see Fig. 3). B 1. You must 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 ANSI Z223.1/ NFPA 54.
  • Page 8: Dimensions And Minimum Installation Clearances

    Appliance details Dimensions and Minimum installation clearances 6 ½" " 5 ¼" " 11 ¼" " 5 ¼" r e s e t 6720644956-01.1V Fig. 6 Dimensions On/Off button Reset button Program key Power ON or stand-by LED LCD display Up button Down button 6 720 644 956...
  • Page 9: Installation Requirements

    Installation requirements Installation requirements Specialized tools The following specialized tools may be required for installation: • Manometer • Multi-meter • Combustion Gas Analyzer. Introduction Please follow these instructions. Failure to follow instructions may result in: B Damage or injury. B Improper operation. B Loss of warranty.
  • Page 10: Installation Using Outdoor Kit (Btok)

    Installation using Outdoor Kit (BTOK) Installation using Outdoor Kit (BTOK) Warnings Danger: the water in this appliance is cold and always remains cold except for Danger: The top of the outdoor kit will the times when the burner is on. In the get very hot during operation.
  • Page 11 Installation using Outdoor Kit (BTOK) 6720644956-03.1V Fig. 8 Before mounting the outdoor kit in the appliance: B 3. Attach the gasket provided with the kit as shown in Fig. 9. 6720645551-11.1V Fig. 10 B Attach the outdoor vent cap to the appliance by fas- tening the two provided screws and washers, see Fig.
  • Page 12 Installation using Outdoor Kit (BTOK) Fig. 12 Dimensions of 940 ESO with Outdoor kit (BTOK) 6 720 644 956...
  • Page 13: Selecting Heater Location

    Installation using Outdoor Kit (BTOK) Selecting heater location Best practice note: The clearances in Fig. 13 and table 1 are the minimum Before proceeding, read the water heater installation allowed by the standard. manual. If the information in that manual is not followed When possible consider maximizing the exactly, a fire, explosion or poisoning by carbon monox- clearances A, B, C, D and E to allow for...
  • Page 14: Mounting Instructions

    Installation using Outdoor Kit (BTOK) Mounting instructions B The water heater is approved for installation directly on an outside wall. Secure the wall mounting bracket provided with the water heater to a wall surface. See Fig. 14. 3½’ B The installation method of the mounting bracket will Vinyl siding depend on the type of mounting surface.
  • Page 15 Do not install the recess box in another configuration. Heater placement and clearances Damages resulting from an improper instal- lation will not be covered by Bosch limited Warning: The water heater with recess warranty. box accessory is intended for an out- door installation only.
  • Page 16 Installation using the Recess Box (7 736 500 043) 6720644960-03.1V Fig. 18 Recess box plumbing/electrical openings Hot water opening Pressure relief valve opening Electrical opening Cold water opening Gas opening Condensing opening B Secure the wall mounting bracket provided with the heater to the wall surface.
  • Page 17: Mounting Installation For Manufactured Mobile) Homes

    Installation for manufactured (mobile) homes Installation for manufactured (mobile) homes Mounting installation for manufac- tured (mobile) homes When installing this appliance on the outside of a man- ufactured (mobile) home, the unit must be additionally secured at the bottom of the water heater as shown in Fig.
  • Page 18: Installation Instructions

    Installation instructions Installation instructions Gas piping & connections Before connecting the gas supply, check the rating plate on the right side of the heater to be sure that the heater is rated for the same gas to which it will be con- nected.
  • Page 19 Installation instructions GAS LINE SIZING The gas supply piping for a single heater should be sized for a maximum draw of 199,000 BTUH. Measure the length of gas supply line and use the tables in Fig. 26, page 20 or the gas line manufacturer’s sizing tables to determine the pipe diameter necessary to accommodate the 199,000 BTU demand of the heater.
  • Page 20 0.3” in Water Column (0.75mbar).(Based on a 0.60 Specific Gravity Gas) Btu numbers given in thousands. Follow boxed numbers for piping just one 940 ESO (example: ¾” B.I. Natural Gas pipe for 10 ft (3.0m). will handle 278,000 btu’s (81.5 kWh). For multiple appliances combine the total maximum btu input load and then refer to applicable chart below.
  • Page 21: Water Connections

    For water analysis data call your local water department, or if on a well, have well water analyzed periodically. If Fig. 27 water quality exceeds one or more of the values specified below, Bosch recommends consulting a local water treatment professional for water softening/ conditioning options. Description Max.
  • Page 22: Domestic Hot Water Recirculation

    Timed or thermostatically controlled operation of the pump is commonly done. Contact Bosch Thermotechnology if further information is needed. 6 720 644 956...
  • Page 23: Space Heating Applications

    GPM). Warning: The use of a flow switch may Bosch tankless water heaters are allowed to be used in be used to ensure DHW priority and to combination DHW and space heating applications prevent “cold-blow” situations when the (open-loop setup).
  • Page 24 Installation instructions 6720644887-02.1V Fig. 32 Space heating diagram Hot water outlet Cold water inlet Pressure relief valve Gas supply Shut off gas valve Thermal expansion tank (as required) Atmospheric vacuum breaker Cold inlet Check valve Pump Thermostatic mixing valve Thermometer (optional) DHW outlet Water to water heat exchanger Backflow preventer...
  • Page 25: Measuring Gas Pressure

    Installation instructions B Record lowest operating gas pressure reading in Measuring gas pressure table 4. Confirm gas pressure upon installation. Gas pressures lower than 3.5" W.C. for Natural Gas or 8" W.C. for LPG will result in insufficient degree rise to Connecting manometer the hot water being used, reduced hot water volume, B Shut off gas supply at installer supplied shutoff valve...
  • Page 26: Electrical Connections

    Electrical connections Electrical connections Electrical power supply Position of the fuses in control unit To check fuses, proceed as follows: Warning: safety reasons, B Remove the front cover, see Fig. 4, page 7. disconnect the power supply cord to the heater before any service or testing B Remove the three screws on front of the control unit.
  • Page 27: Operation Instructions

    Operation instructions Operation instructions Fig. 38 On/Off button Reset button Program Key LCD display Up button Down button LED - Power On indicator or Stand-by Description of LCD display Fig. 42 Lock indicator (only with remote control) Warning: Do not use any cleaning or corrosive agent to clean the window.
  • Page 28: For Your Safety Read Before Operating Your Water Heater

    Operation instructions For your safety read before Temperature selection operating your water heater To select output water temperature: B Press buttons in order to reach desired Warning: If you do not follow these temperature. instructions exactly, a fire or explosion may result causing property damage, personal injury or loss of life.
  • Page 29: Operation

    Operation instructions Solar mode control unit (Fig. 73, component 16) is required when programming the remote control with this heater. The water heater will not ignite if inlet water temperature exceeds the set temperature on the appliance. In this NOTE: up to 6 remote controls can be condition, the solar mode indicator will show on the programmed for one single water heater, LCD display.
  • Page 30: Fan Speed

    Operation instructions Fan speed 9.8.1 Fan speed adjustment IMPORTANT! Installation adjustment: After installing the water heater, the fan speed values for Use the equivalent vent length value to determine the minimum power (P2) and maximum power (P1) may appropriate fan speed value found in the Table 5. Refer need adjustment due to variations in altitude.
  • Page 31 Operation instructions Attention residents of the Commonwealth of signage installed in accordance with the provisions of Massachusetts: 248 CMR 5.08(2)(a)1 through 4. In the Commonwealth of Massachusetts the following (b) EXEMPTIONS: The following equipment is exempt regulation went into effect on 12/30/2005: from 248 CMR 5.08(2)(a)1 through 4: (a) For all side wall horizontally vented gas fueled 1.
  • Page 32: Program Button

    Maintenance and service Program button Caution: Program button can be used on the appliance and in the B Check and clean the complete water remote control. heating system once a year. B Carry out a maintenance overhaul if Programming “Program” function necessary.
  • Page 33: Winterizing For Seasonal Use

    6. Using another line (B), connect to the water outlet To remove the heat exchanger, consult service fitting on the water heater. Route the other end of this bulletin at www.bosch-climate.us. line into a descaling reservoir. 7. Using a 3rd line (C) from the descaling reservoir, 10.2 Winterizing for seasonal use...
  • Page 34: Adjusting Co2

    Maintenance and service B To access measuring port, remove two screws on 16.Reconnect electrical supply to unit, open water shutoff valves, and return the unit to service. either side of the louvered grill. B Pull louvered grill free from vent cap. B Insert CO analyzer probe into the measuring port.
  • Page 35 Maintenance and service B Press the ‘ ’ button until P2 appears. Unit will 3. Verify both P1 and P2 CO readings are within the ramp down to low fire and the flow should decrease. ranges specified in table 7. Repeat steps 1 and 2 as necesssary until CO values are within the specified B Record the CO...
  • Page 36: Program Values

    “P” - button Cascading type This menu is only available when cascade mode is select CC. Contact Bosch Water Heating for details. Master/Slave mode Table 8 Program values, factory default settings and ranges. * Incorrect setting causes errors.
  • Page 37: Control Board Diagnostics

    Maintenance and service 10.6 Control board diagnostics Most recent error/failure 1. Turn on/off switch on water heater to off (O) position. 2nd most recent error B Press and hold the program ' ' button while 3rd most recent error pushing the on/off button to the on (I) position. The display will cycle through a startup procedure 4th most recent error including the software version.
  • Page 38: Troubleshooting

    Many of the questions customers ask regarding operation of this unit can be answered by following the 11.3 Water is too hot troubleshooting steps as outlined below. Visit our web site www.bosch-climate.us more detailed 1. Selected temperature on the unit is set too high. To lower output temperature, see chapter 9.4 , page 28 .
  • Page 39: Low Water Flow/Pressure

    Consult www.bosch-climate.us for a detailed service technician with a calibrated combustion gas analyzer. bulletin on overcoming temperature fluctuations. 2. Unbalanced pressure in water lines. Any restriction in...
  • Page 40: Problem Solving

    Problem solving Problem solving 12.1 Error code diagnostics To remove error code from the display, press the reset button. Display Cause Solution Fault in the flue gas limiter. 1. Check continuity of the flue gas limiter (see Fig. , page Temperature above 230°F...
  • Page 41 2. Check supply voltage. It must be 120VAC and properly (Status message, not an error). grounded. 3. Possible defective control unit call Bosch Water Heating for further instructions. Primary fan rotation too low on 1. Disconnect power supply cord and check wire connection on operation.
  • Page 42 The appliance will close the burner 3. Check vent openings. A blockage may cause this failure. and lock. 4. Call Bosch Water Heating for further instruction. Overheat sensor (ECO) open 1. Disconnect power supply cord and check wire connections on...
  • Page 43 The voltage should measure 24VDC between the left pair of wires and 24VDC between the right pair of wires when the unit is operating. If voltage is not proper, contact Bosch Water Heating for further instruction. 3. Gas valve may be defective, contact Bosch Water Heating for further instrucation.
  • Page 44: Electrical Diagram

    Electrical diagram Electrical diagram T=104°C T=220°F T=110°C T=230°F Casc. input Casc. output Back flow 6720608158-92.1AL Fig. 62 Electrical scheme Intlet water temperature sensor Outlet water temperature sensor Backflow temperature sensor Cascading output connection Cascading input connection Ionization sensor Water flow sensor Flue gas limiter Heat exchanger overheat sensor (ECO) Gas valve...
  • Page 45: Sensor Resistance Charts

    Sensor resistance charts Sensor resistance charts Outlet / Inlet Immersion Sensor characteristics 12 0 2 4 7 2 4 2 2 3 7 2 3 2 2 2 7 10 5 2 2 2 2 17 10 0 2 12 2 0 7 2 0 2 19 7...
  • Page 46: Gwh 940 Eso Functional Scheme

    GWH 940 ESO Functional scheme GWH 940 ESO Functional scheme Fig. 65 Functional scheme 6 720 644 956...
  • Page 47: Interior Components Diagram And Parts List

    Interior components diagram and parts list Interior components diagram and parts list 16.1 Interior components 6720608158-39.2V Fig. 66 Components Flue gas collector Ignition electrodes Heat exchanger Observation window Flame sensor Backflow temperature sensor Primary fan (Mixer) Secondary air fan Outlet temperature sensor Gas valve LCD display Water valve with engine and temperature sensor...
  • Page 48 Interior components diagram and parts list Fig. 67 Appliance overview 6 720 644 956...
  • Page 49: Components Diagram

    Interior components diagram and parts list 16.2 Components diagram 16.2.1 Group 1 6720644956-07.1V Fig. 68 Components Diagram Item Description Reference Item Description Reference Combustion cover clip 8 701 201 032 0 Front cover 8 705 431 408 0 Grommet set 8 710 203 039 0 Cover shield 8 705 506 907 0...
  • Page 50 Interior components diagram and parts list 16.2.2 Group 2 6720902974.AA JF Fig. 69 Components Diagram Item Description Reference Item Description Reference Site window 8 701 000 401 0 Heat exchanger 8 738 701 985 0 Ignition group 8 701 302 249 0 Heat exchanger top gasket 8 704 701 052 0 Heat exchanger O-ring...
  • Page 51 Interior components diagram and parts list 16.2.3 Group 3 6720902975.AA JF Fig. 70 Components Diagram Item Description Reference Item Description Reference Gas / Air Mixer 8 705 700 170 0 Main burner 8 708 120 699 0 Air duct O-ring 8 700 205 149 0 Burner gasket 8 704 701 087 0...
  • Page 52 Interior components diagram and parts list 16.2.4 Group 4 6720608158-73.1AL Fig. 71 Components Diagram Item Description Reference Item Description Reference Gas filter 8 700 507 002 0 Gas valve 8 707 021 019 0 Gasket 8 704 701 085 0 Pressure tapping 8 703 404 219 0 Gas / Fan connector...
  • Page 53 Interior components diagram and parts list 16.2.5 Group 5 6720608158-74.2V Fig. 72 Components Diagram Item Description Reference Item Description Reference O-ring 8 700 205 157 0 Water valve with engine 8 708 505 024 0 Watervalve clip 8 716 102 607 0 O-ring 8 700 205 147 0 Water filter...
  • Page 54 Interior components diagram and parts list 16.2.6 Group 6 6720644956-09.1V Fig. 73 Components Diagram Item Description Reference Item Description Reference Flue gas limiter 8 700 400 032 0 Control unit 8 707 207 366 0 Kit intelligent cascading 7 709 003 962 0 Fuse T2.5A 1 904 521 342 0 Freeze prevention kit (optional)
  • Page 55: Protecting The Environment

    Protecting the en vironment Protecting the environment Packing The packing box may be fully recycled as confirmed by the recycling symbol Components Many parts in the heater can be fully recycled in the end of the product life. Contact your city authorities for information about the disposal of recyclable products.
  • Page 56: For Bosch Tankless Water Heaters

    LIFETIME LIMITED WARRANTY FOR BOSCH TANKLESS WATER HEATERS LIFETIME LIMITED WARRANTY FOR BOSCH TANKLESS WATER HEATERS MODELS COVERED ITEMS NOT COVERED This limited warranty provided Bosch This limited warranty does not cover the following Thermotechnology Corp. (BTC) and covers model 940 circumstances: ESO (hereinafter referred to as "Water Heater").
  • Page 57 LIFETIME LIMITED WARRANTY FOR BOSCH TANKLESS WATER HEATERS INCLUDING BUT NOT LIMITED TO ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. BTC'S SOLE OBLIGATION WITH RESPECT TO THE TANK AND PURCHASER'S EXCLUSIVE REMEDIES ARE SET FORTH IN THE FOREGOING LIMITED WARRANTY.
  • Page 58 LIFETIME LIMITED WARRANTY FOR BOSCH TANKLESS WATER HEATERS 6 720 644 956...
  • Page 59 LIFETIME LIMITED WARRANTY FOR BOSCH TANKLESS WATER HEATERS 6 720 644 956...
  • Page 60 Installation manual should be left with the owner after the installation is tested and completed Replacement Parts available from: BOSCH THERMOTECHNOLOGY CORP. Bosch Termotecnologia SA 50 Wentworth Avenue Estrada de Cacia Londonderry, NH 03053 3800 - 533 Cacia - PORTUGAL Tel. 866-330-2730 www.bosch-climate.us © 2012 Bosch Thermotechnology Corp., Londonderry, NH...

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