940 ESO For Outdoor Installations Only Temperature Modulated with Electronic Ignition Suitable for heating potable water and space heating (Intended for variable flow applications) 6720644956-00.1V 940 ESO - Natural Gas 940 ESO - Liquefied Petroleum (LP) Gas 6 720 644 956 (2010/09) US Warning: If the information in this manual is not followed exactly, a fire or explosion may result causing property damage, personal injury or death.
Index Index 1 Warning 3 2 2.1 2.2 2.3 2.4 2.5 Appliance details Features Specifications (Technical data) Unpacking the heater General rules to follow for safe operation Dimensions and Min. installation clearances 5 5 5 6 7 8 3 3.1 3.2 3.3 Installation requirements Specialized tools Introduction Proper location for installing your heater 4 4.1 4.2 4.3 4.
Warning 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. Correct installation location and proper combustion air supply air supply are very important. If a gas appliance is not installed correctly, fatal accidents can result, such as carbon monoxide poisoning or fire. Warning: Exhaust gas must be vented to outside.
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. FCC: This device complies with Part 15 of the FCC rules. Operation is subject to the following two conditions: (1) This device may not cause harmful interference, and (2) this device must accept any interference received, including interference that may cause undesired operation.
Appliance details 2 Appliance details 2.2 Specifications (Technical data) Approved in US/Canada 2.1 Features Capacity Maximum flow rate: 7.15 GPM (27 l/min) at a 45°F (25°C) rise. Parts • Key Pad interface control • High power pre-mix compact burner with low NOx emissions • Modulating Gas Valve with constant gas:air ratio control • Modulating water valve for improved comfort and temperature control.
Appliance details Dimensions 2.3 • Depth (in): 11¼” (286 mm) In order for proper installation, this water heater must be installed with the outdoor kit (BTOK) accessory. 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. • Width (in): 17 7/8” (452 mm) • Height (in): 30½” (775 mm) • Weight: 67 pounds (30.5 kg).
Appliance details 2.4 To remove front cover B Loosen the two Phillips head screws located on bottom rear of cover (see Fig. 3). 6720644956-02.1V Fig. 3 Loosen the two screws B Lift front cover panel upward and remove. 2 2 1 6720644956-13.1V 1 Fig. 4 Remove the front cover To remove combustion cover (service only) B Open the four clips and remove the combustion cover see Fig. 5. General rules to follow for safe operation B 1. You must follow these instructions when you install your heater.
Appliance details Dimensions and Minimum installation clearances 6 ½" 4 1 16" 5 ¼" 16" 2 1 16 7 8 " 11 ¼" 5 ¼" 30 ½" 17 16" 2 55 16 6 5 16" 2 ¾" 2.5 1 + reset 6 P 3 4 7 5 ¼" 2 5 6720644956-01.1V Fig.
Installation requirements 3 Installation requirements 3.1 Specialized tools The following specialized tools may be required for installation: • Manometer • Multi-meter • Combustion Gas Analyzer. 3.2 Introduction Please follow these instructions. Failure to follow instructions may result in: B Damage or injury. B Improper operation. B Loss of warranty. If you are unable to perform the tasks required to install this heater properly, please contact a locally licensed plumber or gas technician. 3.
Installation using Outdoor Kit (BTOK) 4 Installation using Outdoor Kit (BTOK) 4.1 Warnings Danger: the water in this appliance is cold and always remains cold except for the times when the burner is on. In the event of power outage in conjunction with freezing temperatures, it is recommended that the heater be drained. Danger: The top of the outdoor kit will get very hot during operation. Keep away from children.
Installation using Outdoor Kit (BTOK) A A 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 fastening the two provided screws and washers, see Fig. 11. 6720645551-15.1V Fig. 9 B Position the outdoor vent cap on the top of the appliance, as shown in Fig. 10. 6720645551-12.1V Fig.
Installation using Outdoor Kit (BTOK) 4.3 Selecting heater location Before proceeding, read the water heater installation manual. If the information in that manual is not followed exactly, a fire, explosion or poisoning by carbon monoxide may result causing property damage, personal injury or death. B Choose an outside wall for the installation. Installation on a wall protected by an overhang above is recommended. i Best practice note: The clearances in Fig.
Installation using Outdoor Kit (BTOK) 4.4 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. 13. B The installation method of the mounting bracket will depend on the type of mounting surface. Due to the varieties of building siding or surfacing, the installer must decide on how best to support and level the heater on an outside wall.
Installation using the Recess Box (7 736 500 043) 5 Installation using the Recess Warning: Improper installation! This recess box has been designed to be mounted in a wall cavity with exhaust vent discharging to the outdoors. Do not install the recess box in another configuration. Damages resulting from an improper installation will not be covered by Bosch limited warranty.
Installation using the Recess Box (7 736 500 043) 1 4 2 5 6 3 6720644960-03.1V Fig. 17 Recess box plumbing/electrical openings 1 2 3 4 5 6 Hot water opening Pressure relief valve opening Electrical opening Cold water opening Gas opening Condensing opening1) B Secure the wall mounting bracket provided with the heater to the wall surface. The heater must be kept level on the wall surface, see Fig. 19, page 15. 6720644956-05.1V Fig.
Installation using the Recess Box (7 736 500 043) 6720644956-08.1V Fig. 21 Close the recess box cover with Padlock Warning: Appliance must be installed vertically.
Installation instructions 6 Installation instructions 6.1 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 connected. 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.
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. 24, page 19 or the gas line manufacturer’s sizing tables to determine the pipe diameter necessary to accommodate the 199,000 BTU demand of the heater. If there are more gas appliances on the line, size the gas line according to the total maximum amount of BTU input rating for all appliances.
Installation instructions FOR NATURAL GAS Maximum Capacity of pipe in Cubic Feet of Gas per Hour for Gas Pressure of 0.5 Psig or less and a Pressure drop of 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.
Installation instructions 6.2 Water connections Warning: This heater is not approved for preheated water applications above 140°F (60°C). See chapter 6.4 for approved recirculating application. Warning: In applications where inlet water temperature can exceed 140°F (60ºC), a 3-way valve or mixing valve must be installed before the appliance to prevent water exceeding 140°F (60°C) from entering the appliance.
Installation instructions Connecting the pressure relief valve (PRV) 6.4 A listed pressure relief valve must be installed at the time of installation. No valve is to be placed between the PRV and the heater. No reducing coupling or other restriction may be installed in the discharge line. The discharge line must be a minimum of 4” above a drain and installed such that it allows complete drainage of both the PRV and the line. The discharge line must be placed where it will not cause any damage.
Installation instructions 6.5 Space heating applications Warning: If the set point temperature is above 120 F means should be undertaken to protect users of potable water from scalding. Warning: ensure the primary pump is sized to provide adequate flow for the system heat load. i Warning: Propylene glycol may be used for freeze prevention ONLY on the space heating side of the heat exchanger. Do not use ethylene glycol (automotive antifreeze).
Installation instructions 8 18 13 17 T 5 7 12 22 16 15 1 11 21 14 9 5 20 9 10 2 3 6 9 5 4 6720644887-02.1V 19 Fig.
Installation instructions 6.6 Measuring gas pressure B Record lowest operating gas pressure reading in table 4. Confirm gas pressure upon installation. Connecting manometer B Shut off gas supply at installer supplied shutoff valve for this water heater. B Remove front cover and locate inlet gas pressure measuring point (see Fig. 32). B Loosen screw inside left test point fitting (do not remove) and connect manometer tube to test point. Remove screw completely if correct size tapping is available.
Electrical connections 7 Electrical connections 7.1 Electrical power supply 7.2 Warning: For safety reasons, disconnect the power supply cord to the heater before any service or testing is performed. 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.
Operation instructions 8 Operation instructions Fig. 36 1 2 3 4 5 6 7 8.1 On/Off button Reset button Program Key LCD display Up button Down button LED - Power On indicator or Stand-by Description of LCD display Warning: Do not use any cleaning or corrosive agent to clean the window. Fig. 40 Lock indicator (only with remote control) Fig. 41 Flame indicator Fig. 37 Power bar indicator (input) Fig. 42 Solar mode indicator (see chapter 8.4, page 27) Fig. 38 Temperature indicator Fig.
Operation instructions 8.2 For your safety read before operating your water heater Warning: If you do not follow these instructions exactly, a fire or explosion may result causing property damage, personal injury or loss of life. 8.4 Temperature selection To select output water temperature: B Press buttons temperature. or in order to reach desired A. This appliance is equipped with electronic ignition for lighting the main burner. When turning the heater on, follow these instructions exactly. B.
Operation instructions Solar mode The water heater will not ignite if inlet water temperature exceeds the set temperature on the appliance. In this condition, the solar mode indicator will show on the LCD display. See Fig. 42, page 26. Warning: In applications where inlet water temperature can exceed 140°F (60ºC), a thermostatic or mixing valve must be installed before the appliance to prevent water exceeding 140°F (60°C) from entering the appliance. control unit (Fig.
Operation instructions 8.8 Fan speed 8.8.1 Fan speed adjustment IMPORTANT! Installation adjustment: After installing the water heater, the fan speed values for minimum power (P2) and maximum power (P1) may need adjustment due to variations in altitude. Failure to make necessary adjustments to fan speed values may result in improper operation of the appliance. Use the equivalent vent length value to determine the appropriate fan speed value found in the Table 5.
Operation instructions Attention residents of the Commonwealth of Massachusetts: signage installed in accordance with the provisions of 248 CMR 5.08(2)(a)1 through 4. In the Commonwealth of Massachusetts the following regulation went into effect on 12/30/2005: (b) EXEMPTIONS: The following equipment is exempt from 248 CMR 5.
Maintenance and service 8.9 Program button Caution: Program button can be used on the appliance and in the remote control. B Check and clean the complete water heating system once a year. Programming “Program” function Programming actions are similar for both controls (appliance control pad and wireless remote control). B Carry out a maintenance overhaul if necessary. Immediately repair defects to avoid damage to the system. Annual maintenance table Every year 1. Inspect venting system X 2.
Maintenance and service Descaling • In areas where the water supply has a high mineral content (see Table 2, page 20), the heat exchanger should be periodically flushed with a descaling solution. Scale build up will shorten the life of the water heater and damage resulting from scale is not covered under warranty. Refer to section 9.3 for detailed instructions on descaling the heat exchanger. Fin coils • Inspect heat exchanger fincoil for soot build-up or blockage.
Maintenance and service 16.Reconnect electrical supply to unit, open water shutoff valves, and return the unit to service. B To access measuring port, remove two screws on either side of the louvered grill. B Pull louvered grill free from vent cap. B Insert CO2 analyzer probe into the measuring port. The tip of the probe should be in the center of the flue pipe (approx 1.5" inserted). Avoid air gaps between probe and measuring port as they can alter readings.
Maintenance and service B Press the ‘ ’ button until P2 appears. Unit will ramp down to low fire and the flow should decrease. B Record the CO2 reading in P1 and P2 below. P2 CO2 Reading: % CO2 P1 CO2 Reading: % CO2 Note: When making adjustments, combustion cover is installed. CO2 range (%) make sure 3. Verify both P1 and P2 CO2 readings are within the ranges specified in table 7. Repeat steps 1 and 2 as necesssary until CO2 values are within the specified ranges. 4.
Maintenance and service 9.5 Program values This section describes details on programming the appliance. For most applications, the factory default values will provide robust and stable operation. Only adjust the factory settings if the installation requires changes as indicated in the appropriate section of this manual. Refer to chapter 9.6 Control board diagnostics (page 36) regarding how to access these P-modes.
Maintenance and service 9.6 Control board diagnostics 1. Turn on/off switch on water heater to off (O) position. B Press and hold the program ' ' button while pushing the on/off button to the on (I) position. The display will cycle through a startup procedure including the software version. B Release the ' ' button when '188' appears on the display. The display should read 'P2' when the program button is released. If not, repeat process.
Troubleshooting 10 Troubleshooting Warning: If you are unable to perform the tasks listed below, or need additional assistance please contact your original installer or licensed gas technician. i Inside the heater it is normal to find unplugged wire connectors. These connections are for adding accessories such as cascading or freeze prevention. 10.1 Introduction Many of the questions customers ask regarding operation of this unit can be answered by following the troubleshooting steps as outlined below.
Troubleshooting mix cold water with the hot water leaving the heater. The end result is a cooler water temperature than desired. To check for a plumbing crossover, shut off the cold water supply to the water heater. Then open all of the hot water taps served by the heater. Wait 10 minutes and check all taps for water flow. There should be no water flowing. Any continuous flow of water, small or large, indicates a crossover and must be corrected.
Problem solving 11 Problem solving 11.1 Error code diagnostics i To remove error code from the display, press the reset button. Display Cause Solution Fault in the flue gas limiter. Temperature above 230°F (110°C) inside the cabinet. 1. Check continuity of the flue gas limiter (see Fig. 65, page 47). Go to steps two and three to determine air box temperature sensor fault and replace it. 2.
Problem solving Display (Flashing) (Flashing) Cause Solution Outlet temperature sensor not sensing expected output temperature. (Status message, not an error). 1. Check that the sensor is firmly attached to the hot water pipe (see Fig. 71, page 53). 2. Ensure that outlet temperature sensor is not placed on any bends in the hot water pipe or misreading may occur. 3. Check gas pressure. Low gas pressure may prevent the heater from reaching desired output temperature. 4. Check supply voltage.
Problem solving Display Cause Solution Cold water temperature sensor fault. 1. Check connector on wires coming from top of watervalve for a secure connection. See Fig. 65, page 47. 2. Sensor may trip if water temperature drops below 36°F to protect heater from freezing conditions Any damage due to freezing conditions is not covered under warranty. 3. Check sensor (ref. page 44, chapter 13). Backflow temperature sensor over 309°F. The appliance will close the burner and lock. 1.
Problem solving Display Cause Solution Ionization failure during operation. 1. Check gas type, see Fig. 2, page 6. 2. Check three wire connections to ignition group on the lower front of the heat exchanger are secure. 3. Check vent openings for blockage. Improper venting may cause unstable burner flames and loss of flame ionization. 4. Check that the minimum power fan speed has been adjusted to the proper value. See page 29. 5. Check gas pressure, see section 6.6, page 24. 6.
Electrical diagram 12 Electrical diagram 16 20 15 13 M M 12 M E PS 11 10 19 T=104°C T=220°F 18 9 T=110°C T=230°F 8 FS 7 6 Casc. 5 input Casc. 4 output Back flow 3 2 1 17 16 ... 1 20 ... 1 21 14 JP2 JP7 JP5 JP8 JP6 22 6720608158-92.1AL Fig.
Sensor resistance charts 13 Sensor resistance charts 110 222 2 17 2 12 207 202 19 7 19 2 18 7 18 2 177 172 16 7 16 2 157 152 14 7 14 2 13 7 13 2 12 7 12 2 117 112 10 7 10 2 97 92 87 82 77 72 67 62 57 52 47 42 37 32 10 5 10 0 95 90 85 80 75 70 65 60 55 50 Temp ºC Temp ºF Outlet NTC characteristics 45 40 35 30 25 20 15 10 5 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 Resistance (Kohm) Fig.
Sensor resistance charts 155 302 297 292 287 282 277 272 267 262 257 252 247 242 237 232 227 222 2 17 2 12 207 202 19 7 19 2 18 7 18 2 17 7 17 2 16 7 16 2 15 7 15 2 14 7 14 2 13 7 13 2 12 7 12 2 117 112 10 7 10 2 97 92 87 82 77 72 67 62 57 52 47 42 37 32 150 14 5 14 0 13 5 13 0 12 5 12 0 115 110 10 5 10 0 95 90 85 80 75 70 Temp ºC Temp ºF Back Flow characteristics 65 60 55 50 45 40 35 30 25 20 15 10 5 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26
GWH 940 ESO Functional scheme 14 GWH 940 ESO Functional scheme IDLE Water flow > 0.5 gpm (> 1.9 l/min) (see WF calc.) water tap open? See error code table NO YES Fan speed = correct Ionization = off Temp. limiter = closed Temp. sensors = ok Over heat protection = ok Appliance ready to start? YES Fan speed OK? NO NO NO waiting time of 10s passed? YES YES Start sparking Open the gas valve INPUTS: - FANSPEED - WATER TEMP.
Interior components diagram and parts list 15 Interior components diagram and parts list 15.1 Interior components Fig.
Interior components diagram and parts list Fig.
Interior components diagram and parts list 15.2 Components diagram 15.2.1 Group 1 12 10 5 6 8 9 7 3 11 4 2 1 6720644956-07.1V Fig.
Interior components diagram and parts list 15.2.2 Group 2 3 2 1 5 4 8 9 6 7 6720902974.AA JF Fig.
Interior components diagram and parts list 15.2.3 Group 3 5 1 2 4 3 6 9 16 13 12 8 11 7 15 14 17 6720902975.AA JF Fig.
Interior components diagram and parts list 15.2.4 Group 4 14 11 10 13 12 11 6 7 9 1 8 2 5 3 4 6720608158-73.1AL Fig.
Interior components diagram and parts list 15.2.5 Group 5 4 3 12 4 1 5 6 2 8 13 7 11 12 9 10 9 11 15 16 17 14 6720902977.AA JF Fig.
Interior components diagram and parts list 15.2.6 Group 6 4 8 5 6 7 9 10 3 2 11 1 14 15 16 12 13 6720644956-09.1V Fig. 72 Components Diagram Item Description Reference Item Description Reference 1 Control unit 8 707 207 368 9 Electrode cables 8 704 401 346 1 904 521 342 10 Flue gas limiter 8 700 400 032 Kit intelligent cascading (optional) 7 709 003 962 7 709 003 665 2 Fuse T2.5A 3 Fuse T1.
Protecting the en vironment 16 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. Saving water resources: B Make sure you close all the taps after any use. Avoid leaving the taps dripping. Repair any leaking tap.
Limited Warranty 17 Limited Warranty General Service Labor Costs BOSCH PRO tankless water heaters are warranted by the Manufacturer (BOSCH) through Bosch Thermotechnology Corp. Bosch Thermotechnology Corp. will furnish a replacement heat exchanger and will furnish a replacement of any other part which fails in normal use and service within the applicable periods specified below, in accordance with the terms of this warranty. The Bosch Thermotechnology Corp.
Limited Warranty 6 720 644 956 57
Limited Warranty 58 6 720 644 956
Limited Warranty 6 720 644 956 59
6720644956 Installer Checklist to be completed 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 __________ Installing Company _____________________________________________ Installer name _____________________________________________ Address ________________________________________
