Bosch Tronic 6100 C Electric Tankless Water Heaters Installation Manual

1 Key to Symbols and Safety Instructions

1.1 Key to Symbols

Warnings in this document are identified by a warning triangle (⚠️) printed against a grey background. Keywords at the start of a warning indicate the type and seriousness of the ensuing risk if measures to prevent the risk are not taken.

Keywords:

• DANGER: Indicates a hazardous situation which, if not avoided, will result in death or serious injury.
• WARNING: Indicates a hazardous situation which, if not avoided, could result in death or serious injury.
• CAUTION: Indicates a hazardous situation which, if not avoided, could result in minor to moderate injury.
• NOTICE: Used to address practices not related to personal injury.

Important Information: This symbol (ℹ️) indicates important information where there is no risk to people or property.

1.2 Safety

Installation should be made in accordance with the regulations of the Authority Having Jurisdiction (AHJ), local code authorities, and utility companies. The AHJ may be a federal, state, or local government entity, or an individual such as a fire chief, building official, or electrical inspector.

WARNING: IMPORTANT SAFETY INSTRUCTIONS

When using electrical appliances, follow basic safety precautions to reduce the risk of fire, electric shock, or injury:

1. Read all instructions before using this water heater.
2. This water heater must be grounded.
3. Install or locate this water heater only in accordance with the provided installation instructions.
4. Do not use this water heater for anything other than its intended purpose, as doing so could result in property damage and void the warranty.
5. This heater has more than one power supply connection point. Always shut off all power to the unit at the main electrical panel before attempting to install, clean, inspect, repair, disassemble, or service the heater.
6. Power supply wires must be rated to 194°F (90°C). Refer to technical specifications for proper wire size.
7. The heater must be connected to dedicated circuit breakers. If the heater is not within sight of the electrical circuit breakers, provide a lockout or additional means of disconnection within sight of the appliance.
8. The plumbing installation must be completed before the electrical installation.
9. The plumbing installation requires non-ferrous metal pipes or reinforced stainless steel water heater connectors that can withstand pressure up to 150 psi.
10. To ensure proper operation, the water supply flow rate must be at least 0.5 gpm.
11. Do not install the heater where it may be subjected to direct sunlight, rain, splashing water, or freezing temperatures.
12. Before connecting to a public power network, consult the local power supply authority to ensure the network meets the stated requirements.
13. Do not operate this water heater if it has damaged wiring, is not working properly, or has been damaged or dropped.
14. This water heater should only be serviced by qualified service personnel. Contact the installer or a qualified service agency for examination, repair, or adjustment.

WARNING: IMPROPER OR DANGEROUS OPERATION

Installations must comply with all applicable local, state, provincial, and national codes, laws, regulations, ordinances, and the latest version of the National Electrical Code, NFPA No. 70.

WARNING: IMPROPER OR DANGEROUS OPERATION

Do not operate if the water heater is exposed to:

• Fire
• Damage
• Water
• Freezing temperatures

Failure to follow this information could result in property damage, severe personal injury, or death.

WARNING: INDOOR INSTALLATION ONLY

DO NOT INSTALL OUTDOORS. This water heater is certified for indoor installation only. Failure to install indoors could result in FIRE, PROPERTY DAMAGE, and/or PERSONAL INJURY OR DEATH.

WARNING: FIRE

Install all system components and piping in a manner that does not reduce the performance of any fire suppression devices or systems.

WARNING: IMPROPER OR DANGEROUS OPERATION

DO NOT USE THIS WATER HEATER IF ANY PART HAS BEEN SUBMERGED IN WATER. Immediately call a qualified service technician. The water heater MUST BE replaced if it has been submerged. Operating a submerged water heater could create harmful conditions such as fire, explosion, or release of mold, bacteria, or other harmful particulates. Such operation could result in property damage, severe personal injury, or death. Water heater damage due to flood or submersion is considered an Act of God and is NOT covered under product warranty.

WARNING: IMPROPER OR DANGEROUS OPERATION

The manufacturer cannot be responsible for damages caused by improper installation or by failure to follow the instructions in this manual.

WARNING: HAZARDOUS VOLTAGE

When servicing the water heating system, be sure to disconnect electrical power before performing service. Failure to do so could result in electrical shock, property damage, serious personal injury, or death.

WARNING:

This product can expose you to chemicals including Lead and Lead components, which are known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.

NOTICE: PRODUCT DAMAGE, PROPERTY DAMAGE

Do not use petroleum-based cleaning or sealing compounds in a water heating system, as gaskets and seals may be damaged, resulting in substantial property damage.

NOTICE: PRODUCT DAMAGE, PROPERTY DAMAGE

If the water heater has been stored in a very cold location (below 32°F) before installation, handle with care until components reach room temperature to prevent damage.

2 Prepare the Water Heater

Water Temperature Adjustment

The water heater thermostat is factory-set to 125°F (52°C). Follow local codes. If setting the temperature above 120°F, install an ASSE 1017 rated mixing valve to avoid severe burns or death from scalding temperatures.

After adjusting the thermostat, allow sufficient time for the water to reach the set temperature. The recommended setting is 120°F.

WARNING: SCALD HAZARD

Scald injury is heightened by increased water temperatures. Hot water can produce 3rd-degree burns in less than 5 seconds at 140°F and in approximately 30 seconds at 130°F. If the thermostat is set too high, there is a serious potential for scalding. Children, the disabled, and the elderly are at the highest risk of being scalded.

2.1 Inspect Shipment

Inspect shipment for possible damage. The manufacturer's responsibility ceases upon delivery. File claims for damage, shortage, or non-delivery immediately against the carrier.

2.2 Water Heater Rating Label Location

When inquiring about service or troubleshooting, reference the model and serial numbers from the water heater rating label. The serial number can also be found inside the unit. [Diagram showing the location of the rating label on the front of the unit, with callouts for Model Number, Serial Number, Max Power, etc.]

2.3 Clearances

Ensure adequate room for service. Minimum recommended service clearances are:

A removable panel can provide front clearance. This water heater is approved for closet installation. Failure to provide minimum clearances may make servicing difficult.

WARNING: FIRE, EXPLOSION

Keep flammable materials at least 24" (61cm) away from the water heater and hot outlet pipe.

NOTICE: PRODUCT DAMAGE

High heat sources (generating heat 100°F / 37°C or greater) may damage plastic components. Maintain a minimum clearance of 8" from high heat sources. Observe heat source manufacturer instructions and all applicable codes.

2.4 Locating the Water Heater

WARNING: INDOOR INSTALLATION ONLY

DO NOT INSTALL OUTDOORS. Failure to install indoors could result in property damage, severe personal injury, or death.

NOTICE: PROPERTY DAMAGE

All water heaters can eventually leak. Locate the water heater where any leakage will not cause damage to surrounding areas or lower floors. National Plumbing codes require a drain pan. Leakage damages are not covered by warranty. Consider installing water leak detection devices and automatic shutoff valves.

2.4.1 Installation Area (Mechanical Room) Operating Conditions

The water heater must be installed upright in the vertical position on a plumb surface.

WARNING: IMPROPER OR DANGEROUS OPERATION

DO NOT install the water heater in any other orientation than upright and vertical. Doing so will result in improper operation, property damage, and could cause serious personal injury or death.

Ensure ambient temperatures are higher than 32°F (0°C) and lower than 104°F (40°C). Attic ambient temperatures may frequently exceed 104°F.

WARNING: IMPROPER OR DANGEROUS OPERATION

Incorrect ambient conditions can lead to damage and unsafe operation. Ensure the installation location adheres to manual information. Failure to do so could result in property damage, serious personal injury, or death.

Avoid areas with high humidity, moisture, dust, or splashing water. Do not install under water pipes or air conditioning lines that might leak or condense.

WARNING: SCALD HAZARD

Keep the water heater and hot outlet piping out of reach of children to prevent tampering or contact with hot pipes.

NOTICE: PRODUCT DAMAGE, PROPERTY DAMAGE

Proximity to damp and salty marine environments can degrade metallic surfaces and cause premature failure, which is not covered by warranty.

2.4.2 Centralized Location

Choose a location centralized to piping and electrical systems, protected from freezing, and with accessible controls, inlets, and outlets. Keep piping runs to fixtures minimal to reduce heat loss and friction loss. Insulate all piping.

In California, the water heater must be braced, anchored, or strapped to avoid movement during an earthquake. Contact local utilities for code requirements or visit www.dsa.dgs.ca.gov.

WARNING: FIRE, EXPLOSION

Do not locate near flammable liquids (gasoline, butane, propane, adhesives, solvents, paint thinners) as controls could ignite vapors, causing explosion, property damage, severe personal injury, or death.

2.4.3 Replacing an Existing Water Heater

When replacing an existing water heater, check for and correct any existing system problems, such as system leaks or locations prone to freezing.

3 Water Quality Requirements

CAUTION: PROPERTY DAMAGE, PRODUCT DAMAGE

Water supply composition can affect efficiency and cause severe damage. Water quality must be professionally analyzed. Adverse water quality affects reliability. Operating temperatures above 135°F accelerate lime scale build-up, potentially shortening service life. Failures due to lime scale, low pH, or chemical imbalance are not covered by warranty.

The water must be potable, free of corrosive chemicals, sand, and dirt. It is the installer's responsibility to ensure the water does not contain corrosive chemicals that can damage the heat exchanger. Potable water complies with EPA secondary maximum contaminant levels (40 CFR Part 143.3). If water contains contaminants higher than outlined, water treatment and more frequent maintenance may be required. Discontinue use and contact a technician if water is suspected to be contaminated.

NOTICE: PRODUCT DAMAGE

Failure of electric elements due to lime scale build-up, low pH, or other imbalance is not covered by warranty.

Hard water (over 250 mg/liter) can cause scale build-up and damage. Use an anti-scale treatment for hard water. Damage caused by scale is not covered by warranty.

4 Water Heater Components

[Diagram showing the Bosch Tronic 6100 C water heater with internal components labeled: 1. Power Button, 2. Digital Temperature Display, 3. Temperature Setting Buttons, 4. LED Indicator, 5. Cold Water Inlet, 6. Hot Water Outlet, 7. Electrical Knockout/Strain Relief, 8. Inlet Water Filter, 9. Triac, 10. Heating Canister, 11. Heating Element, 12. High Limit Switch, 13. Terminal Block, 14. Ground Connection, 15. Thermistor, 16. Flow Switch.]

5 Dimensions

[Diagram showing the Bosch Tronic 6100 C water heater with dimensions indicated: Height 13 1/4", Width 8 1/2", Depth 6 1/16", Front to outlet 6 3/8", Back to outlet 5 1/8".]

6 Technical Specifications

* Performance will reduce if voltage reduces.

7 Installation

7.1 Wall Mounting the Water Heater

1. Remove the two (2) shipping screws from the back of the unit.

2. Remove two (2) screws from the bottom of the cover and save them for reinstallation.

3. Pull the bottom of the cover forward and swing it out (pos. 1). Lift it away from the tabs on the top of the back cover (pos. 2). Do not fully remove the cover yet.

NOTICE: PRODUCT DAMAGE!

Before proceeding, be aware that a wiring harness connects the front cover to the unit. Disconnect this harness to fully remove the cover. DO NOT pull the cover away completely without first disconnecting the wiring, or damage may occur.

4. Disconnect the wiring harness connected to the inside of the front cover.

5. Remove the cover completely.

6. Choose a suitable, solid, and secure mounting surface.

WARNING: ELECTRIC SHOCK HAZARD

Do not install the unit above electrical boxes or junctions.

7. The appliance must be mounted upright, with water inlets and outlets at the bottom.

WARNING: IMPROPER OPERATION, PERSONAL INJURY, PRODUCT DAMAGE

This water heater must be installed upright and vertical. DO NOT install in any other orientation, as this will result in improper operation, property damage, and could cause serious personal injury or death.

[Diagram illustrating correct upright mounting versus incorrect upside-down, on-side, or on-back mounting.]

8. Position the unit on the mounting surface, ensuring it is plumb.

9. Mount the unit to the wall using four (4) screws of at least one (1) inch (25.4mm) in length at the marked points. [Diagram showing mounting hole locations and screw placement, indicating dimensions 3 7/8", 13", 3 7/8".]

Mounting screws are not included with the product.

NOTICE: PROPERTY DAMAGE, PRODUCT DAMAGE

Use screws suitable for the wall material and the weight of the water heater. Failure to do so could result in property damages and damage to the water heater, which are not covered by warranty.

10. Gently pull on the water heater to ensure it is properly mounted.

7.2 Plumbing

All plumbing must be done in accordance with federal, local, and state plumbing codes and practices. Failure to properly install the water heater WILL VOID the warranty. Use thread tape on all mechanical plumbing connections.

• Minimum pipe size should match water heater connection.
• The installer is responsible for all equipment and components required by local codes. In Massachusetts, a vacuum relief valve must be installed per 248 CMR. 4.
• A temperature and pressure (T&P) relief valve may be required by local, state, or provincial codes. If required, install according to code and manufacturer instructions.
• Mixing valve applications are recommended to help prevent scalding.
• It is highly recommended to install water leak detection devices and automatic shutoff valves where leakage could cause property damage.
• Do not use plastic or PEX type piping within 3 feet of the heater.
• All water pipes within three (3) feet of the unit's water inlet and outlet must be rated for high temperature applications of 185°F (85°C) minimum.

Do not apply thread tape on the first two threads. Keep clear to prevent materials entering the water path.

1. Install unions on the hot and cold water connections to easily disconnect the water heater for servicing. [Diagram showing unions on inlet/outlet connections.]

Before connecting pipes, flush the lines to eliminate all residue and debris.

The maximum operating water pressure of this water heater is 150 psi / 10 bar. Residential systems with unstable pressure or pressure above 73 psi require a pressure reducing valve set to 58-73 psi.

NOTICE: PRODUCT DAMAGE

Failure due to lime scale build-up, low pH, or other imbalance is not covered by warranty. See Section 3 Water Quality Requirements.

7.2.1 Pressure Relief Valve

A pressure relief valve (PRV) may be installed for protection against excessive pressures. Refer to local codes to see if installation is required. Install the PRV (max set pressure 150 psi) on the hot outlet line, orienting it or providing tubing so discharge exits at least 6" above the structural floor. The relief line must not contact live electrical parts and its opening must not be blocked or reduced.

Commonwealth of Massachusetts: A pressure relief valve must be installed on the hot water side by a licensed plumber (MGL 142 Section 19).

DANGER: PERSONAL INJURY, PROPERTY DAMAGE, PRODUCT DAMAGE

Never thread a cap or plug into a relief valve or relief valve line. Explosion, property damage, serious injury, or death may result.

2. Connect the water inlet line to the heater's right side inlet and the outlet line to the water outlet. Use a line rated for a minimum pressure of 150 psi.

NOTICE: PRODUCT DAMAGE

Do not solder piping directly to the unit's connection points. If using sweat connections, sweat tubing to the adapter before fitting the adapter to the heater. Excessive heat will damage the heater. Use two wrenches when tightening water piping; one to prevent the line from turning. Do not overtighten. Damages from improper installation are not covered by warranty.

7.3 Installation Example

[Diagram illustrating a typical installation setup showing cold water inlet, hot water outlet, check valve, ball valve, automatic water shut-off valve, pressure relief valve (if required), drain, water leak detection sensor, and unions.]

7.5 Scalding

WARNING: SCALD HAZARD

An ASSE 1017 or ASSE 1070 temperature limiting or mixing valve is recommended for installations serving disabled persons, the elderly, or children. Mixing valves do not eliminate scalding risk. To avoid scalding:

• Set the water heater set point temperature as low as possible.
• Feel water before bathing or showering.
• If thermostatic valves are required, use devices specifically designed for this purpose and follow manufacturer instructions.

Failure to install a temperature limiting or mixing valve and follow these instructions could result in property damage, severe personal injury, or death due to scalds.

This water heater can deliver scalding water. Be careful when using hot water. Some appliances may require higher temperatures; setting the thermostat higher for these appliances may create a scald risk. Install a mixing valve to reduce point-of-use discharge temperatures.

Table 1 details the relationship between water temperature and time to produce a serious burn, which can guide safe temperature settings.

7.6 Filling the Heater

1. Ensure all drain valves in the system are closed.

2. Open the shut-off valve in the cold water supply line.

3. Open hot water faucets to allow air to vent from the heater and piping.

4. Allow sufficient time for the heater to completely fill with water.

5. Check for and repair any leaks.

If a water leak is detected, turn off the water supply at the main shut-off valve and contact Customer Service (Phone: 1-866-642-3198).

NOTICE: PRODUCT DAMAGE, PROPERTY DAMAGE

When filling, open a hot water tap to release air. The heating canisters must be full of water before the heater is turned on. Failure to do so could result in damage to the water heater and other property, which is not covered by warranty.

7.7 Electrical Connection

DANGER: HAZARDOUS VOLTAGE

Failure to disconnect power before attempting installation or repair will result in property damage, severe personal injury, or death.

WARNING: PERSONAL INJURY, PROPERTY DAMAGE

All wiring (wire gauge) and circuit protection (breakers) must comply with the National Electrical Code (NEC) and be performed by a qualified licensed electrician or the local electric utility.

WARNING: ELECTRIC SHOCK HAZARD

Ensure the water heater is properly grounded. Failure to do so could result in property damage, severe personal injury, or death.

NOTICE: PRODUCT DAMAGE, PROPERTY DAMAGE

The water heater must be full of water before power is turned on. Energizing the heating element while the canister is dry will cause damage. Failures due to "dry-firing" are not covered by warranty.

1. Connect each wire pair to one breaker (see Wiring Diagrams). Ensure each breaker connects to one black wire and one red or white wire. Shut off power to the unit via the dedicated circuit breakers in the main electrical panel.

2. Use a suitable wire gauge that meets applicable electrical codes for the breaker size. Run power cable wires from the main electrical panel to the water heater. Connect the power cable to the terminal block inside the water heater.

3. Each incoming circuit requires a separate ground connector.

4. Double-check all electrical connections for correctness, tightness, and security. Confirm the correct breaker size and wire gauge are used and the unit is grounded according to applicable codes.

Ensure all connections are correctly made for proper operation. Mixing wires can lead to unit failure.

5. Replace and reattach the front cover with two (2) screws.

6. Ensure all air is purged from water lines before turning on power. Refer to Step 3 in the plumbing installation section. Restore power via the main electrical panel breakers.

This water heater must be installed in accordance with all applicable local, state, provincial, and national electrical codes.

The heater must be connected to dedicated circuit breakers.

18-27kW models require 3 sets of wires and ground. See Wiring Diagrams.

7.8 Wiring Diagrams

7.8.1 Power Supply Wiring for 18 and 27kW

[Diagram showing power supply wiring for 18kW and 27kW models. It illustrates connections to terminal blocks and grounding blocks, indicating L1, L2, and ground connections for 240V circuits. Text notes that 10 AWG wire is required for 18kW and 8 AWG for 27kW, with ground, for each 240V circuit. It also states that voltage phasing is important and voltage between L1 terminals should be less than 5V.]

[Diagram showing internal PCB dip switches.]

NOTICE: PRODUCT DAMAGE

Do not alter or change the position of dip switches to ensure correct operation.

7.8.2 Internal Wiring Diagram for 18kW

[Diagram showing the internal wiring for the 18kW model, illustrating connections from the PCBA Control Unit to heating elements (H.E. 1, H.E. 2, H.E. 3) via TRIACs and thermostats, and connections to sensors (Flow Sensor, In Temp Sensor, Out Temp Sensor) and the Heater Display.]

7.8.3 Internal Wiring Diagram for 27kW

[Diagram showing the internal wiring for the 27kW model, illustrating connections from the PCBA Control Unit to heating elements (H.E. 1, H.E. 2, H.E. 3) via TRIACs and thermostats (Thermostat 1-5), and connections to sensors (Flow Sensor, In Temp Sensor, Out Temp Sensor) and the Heater Display.]

8 Installation Checklist

Use this checklist to ensure proper installation:

9 Operation

This tankless electric water heater provides hot water instantaneously on demand. It heats water quickly as needed. Unlike conventional tank heaters, it does not store hot water, making it more energy-efficient.

Sensors monitor water flow and temperature, transmitting data to the controller, which adjusts power to the heating elements for the set temperature. Read all setup and operating instructions carefully for maximum performance and energy savings.

NOTICE: PRODUCT DAMAGE, PROPERTY DAMAGE

The water heater must be full of water before power is turned on. Energizing the heating element while the tank is dry will cause damage. Failures due to "dry-firing" are not covered by warranty.

Setting the Outlet Water Temperature

• Press the [power button emoji ▶️] button to power on the unit.
• Press the [up arrow emoji ⬆️] or [down arrow emoji ⬇️] buttons to increase or decrease the temperature.
• Temperature can be set from 86°F to 125°F (30°C to 52°C).

Setting Recommendations:

• A comfortable temperature for bathing and showering is 105°F to 110°F (41°C to 43°C).
• The recommended setting is 120°F (49°C) for maximum flow rate and household needs.
• Higher temperature settings are not recommended as they can cause serious scalding injuries, especially to children and the elderly.
• Higher temperatures also produce more scale buildup.

If the unit is not achieving the set point, reduce the flow rate (refer to Table 5).

The display lights up only when the unit is operating or the user changes the set temperature.

Turning the Unit On

• Press the [power button emoji ▶️] button. The unit will power on.
• Press the [power button emoji ▶️] button again to turn the unit off.

10 Seasonal Operation

Vacation/Freezing Temperatures

Due to the design, it is difficult to completely drain all water from the heater. Follow these steps to minimize the chance of freeze damage:

1. Disconnect electric supply.
2. Disconnect cold and hot water pipes from the heater fittings. Allow water to drain out (use a catch basin).
3. Use compressed air to purge remaining water from the heating canisters.

These suggestions are made to minimize potential freeze damage and are not a guaranteed method.

11 Maintenance

WARNING: PERSONAL INJURY, PROPERTY DAMAGE

Do not attempt to repair this water heater yourself. Call a qualified service technician. Always turn off power at the circuit breaker before servicing or draining. Failure to do so could result in property damage, severe personal injury, or death.

WARNING: ELECTRICAL HAZARD

Turn off power at the circuit breaker and remove the front cover before performing maintenance.

For most maintenance, water will need to be drained from the heater.

Periodic maintenance extends heater life and ensures maximum performance. Inspect for damage, cracks, leakage, or weakness and address immediately. Do not overtighten connections.

Water heated at higher temperatures produces scale faster. Install manual shut-off/maintenance valves on inlet and outlet. Flush the unit annually, or every six months if water is unusually hard.

11.1 Removing the Cover

1. Remove the two (2) screws from the bottom of the cover and save for reinstallation.

2. Pull the bottom of the cover forward and swing it out (pos. 1). Lift it away from the tabs on the top of the back cover (pos. 2). Do not fully remove the cover yet.

NOTICE: PRODUCT DAMAGE!

A wiring harness connects the front cover to the unit. Disconnect this harness before fully removing the cover. DO NOT pull the cover away completely without disconnecting the wiring first, or damage may occur.

3. Disconnect the wiring harness connected to the inside of the front cover.

4. Remove the cover completely.

11.2 Cleaning the Inlet Pre-Filter

1. Remove and clean the pre-filter on the inlet water side annually, or anytime maintenance is performed.

2. Wash lightly to remove debris.

3. Reinstall the filter and purge air from the system before turning on power.

WARNING: ELECTRICAL HAZARD

When performing maintenance that may introduce air into the pipes, turn off power to the water heater and purge air from the lines before restoring power. Follow "Filling the Water Heater" instructions. Failure to do so could result in permanent damage to the heating element and void the warranty.

11.3 Draining the Heater

The water heater can be emptied by:

• Siphoning water out through a lower service valve on the inlet side.
• Keep a hot water faucet open while siphoning.

11.4 Removing a Heating Element

1. Shut off power supply and drain the water heater.

2. Remove the front cover per Section 11.1.

3. Disconnect all six (6) wires connected to the heating element.

4. Use a suitable wrench to remove the element containing cap from the water heating canister.

Note: Residual water may remain in the canister even after draining.

5. To remove the heating element, unlock it from the tab inside the heating canister. Push the element bottom up slightly into the canister, then rotate to release it from the tab. [Diagrams illustrating the process of unlocking and removing the heating element from the canister.]

6. Pull down to remove the heating element.

7. Install the new element with the red O-ring, ensuring correct positioning. Replacing the O-ring is recommended to prevent leaks.

8. Insert the new heating element into the heating canister.

9. Align the tab inside the heating canister with the notch in the element bottom. Push the element bottom up slightly into the canister above the tab, then rotate to align the notch with the tab. Pull the element down to seat the notch in the canister tab. [Diagrams illustrating alignment and seating of the new element.]

10. Reinstall the element containing cap to secure the element.

11.5 Descaling the Heating Element

Scale deposits can affect heating capability and damage the element.

NOTICE: PRODUCT DAMAGE

Failure of electric elements due to lime scale build-up, low pH, or other imbalance is not covered by warranty.

The element can be descaled chemically or manually.

To descale chemically:

1. Soak the element in white vinegar or an approved food-grade descaling solution for potable water systems.
2. Rinse thoroughly with a fresh water / baking soda solution.

To descale manually:

1. After the element has dried, use a soft, non-metallic brush to remove dried minerals from the stainless steel sheath.

Reinstall the element after descaling.

NOTICE: PRODUCT DAMAGE, PROPERTY DAMAGE

The water heater must be full of water before power is turned on. Energizing the heating element while the canister is dry will cause damage. Failures due to "dry-firing" are not covered by warranty.

11. Reconnect all wires to the heating element. [Diagram showing wire reconnection.]

Note: Heat shrink/electrical tape must be applied to connectors to cover screws and prevent product damage.

12. Refill the water heater with water before restoring power. Replace the cover and verify proper operation.

NOTICE: PRODUCT DAMAGE, PROPERTY DAMAGE

The water heater must be full of water before power is turned on. Energizing the heating element while the canister is dry will cause damage. Failures due to "dry-firing" are not covered by warranty.

12 Troubleshooting

Consult this list for common issues before calling for service. Contact your installer or Customer Service (Phone: 1-866-642-3198) if problems persist.

For FAQs, videos, and service bulletins, visit www.boschheatingcooling.com/service or scan the QR code [QR Code for Service & Support].

WARNING: ELECTRICAL HAZARD

Failure to disconnect power before attempting installation or repair will result in property damage, severe personal injury, or death.

WARNING: SCALD HAZARD

Increasing water temperature increases scald risk. Lower settings are more economical and reduce scald risk. Use a water tempering or mixing valve and exercise extreme caution with hot water. Consult codes for conformance. Failure to follow these instructions could result in serious personal injury or death from scalds.

NOTICE: PRODUCT DAMAGE

If draining the water heater is necessary, open the T&P valve or a hot water tap to prevent vacuum buildup in the heating canister and piping.

12.1 High Limit Switches

WARNING: ELECTRICAL HAZARD

Disconnect power before installation or repair to prevent property damage, severe personal injury, or death.

High temperature limit switches may trip due to water temperature exceeding 135°F (57°C), shutting off power as a safety precaution. The tripped switch needs to be reset.

Resetting Manual High Limit Switch (with center button):

1. Ensure all circuit breakers supplying the water heater are OFF.
2. Press the reset button. If a click is heard, the switch was tripped and has been reset.
3. Turn circuit breakers back ON and run a hot water faucet to test activation.

Resetting Automatic-Reset High Limit Switch (no button):

This switch should reset itself once the overheat condition ends. Open a hot water faucet and allow one minute for the switch to reset. If it does not reset, test for failure:

1. Ensure all circuit breakers are OFF.
2. Use a multimeter to test for continuity across the cooled limit switch. If continuity exists, the switch has reset. If no continuity and the switch is cool, it may have failed and requires replacement.

CAUTION: PRODUCT DAMAGE, PROPERTY DAMAGE

Repeated tripping of the High Limit Switch (TCO) indicates a problem. Call a technician if frequent resetting is needed. Measure resistance across contacts after resetting.

12.2 Checking Thermostat Operation

To check thermostat operation:

1. Press the [power button emoji ▶️] button to activate the heater. The display will show the outlet temperature.
2. With water running, press [up arrow emoji ⬆️] or [down arrow emoji ⬇️] to adjust the temperature. The recommended setting is 120°F (49°C).

A lower setting is more economical and reduces scald risk.

3. After adjusting temperature, allow the heater time to heat the water. Measure the water temperature at a hot water outlet.

12.3 Testing the Heating Element

To Test Heating Element:

1. Verify circuit breakers are off and there is no voltage at the unit.
2. Disconnect wires from the heating element. Mark wire positions for reinstallation.
3. Using a 200 ohm range on a digital multimeter, measure resistance (ohms) across the wire connections on the base of each heating element canister. Ensure probes make good contact. Test points are A+ to A-, B+ to B-, C+ to C-. [Diagram showing test points on heating element connections.]

4. If an element tests bad, replace it following the procedure in Section 11.4.

12.4 Testing/Changing a Triac

A failed triac can cause overheating, irregular heating, or no heating. If other troubleshooting steps fail, test the triacs.

WARNING: ELECTRICAL HAZARD

Disconnect power before installation or repair to prevent property damage, severe personal injury, or death.

1. Shut off power supply to the water heater.

2. Remove the front cover per Section 11.1.

3. Remove the three screws holding the internal protective cover.

4. Locate the triacs. [Diagram showing triac locations.]

To Test Triac:

1. Measure resistance (Ω) across terminals as shown. [Diagram showing triac test points A1, A2, G.]

To Change Triac:

1. Ensure power supply is OFF.
2. Take a photo of the triac wiring for reinstallation. Disconnect the three (3) wire connectors on the triac and remove the wires. [Diagram showing wire disconnection.]
3. Remove the two (2) screws holding the triac to the inlet pipe. Remove the triac. [Diagram showing triac removal.]
4. Install the new triac using the two (2) screws.
5. Re-attach the wiring to the triac.
6. Re-attach the internal protective cover and front cover.
7. Return the heater to service.

If further assistance is needed, contact technical support via Email (www.boschheatingcooling.com/contact) or Phone (1-866-642-3198). Alternatively, visit the Service & Support webpage or scan the QR code [QR Code for Service & Support].

Notes