WSH8545 Instant Electric Water Heater PCBA

Wide-Voltage Instant Electric Water Heater PCBA with Intelligent Temperature and Flow Control

The XX-WSH-01P6K-REV13 and HS-WSH-8545J-3KEY-XH3-C1.1 form a customizable PCBA control solution for residential and commercial instant electric water heaters.

Based on an APT control platform, this instant electric water heater PCBA integrates wide-voltage operation, temperature adjustment, water-flow detection, intelligent display control, automatic parameter learning, audible feedback and multiple safety-protection functions.

The solution can be customized according to the customer’s heating element, product enclosure, touch panel, water path, rated power and target-market electrical requirements.

Key Specifications

Power Board Model: XX-WSH-01P6K-REV13

Display Board Model: HS-WSH-8545J-3KEY-XH3-C1.1

Control Platform: APT-Based Control Solution

Power Supply Design: Switch-Mode Power Supply

Input Voltage Range: 85–280 VAC

Optional Transformer Solution: 180–265 VAC

Temperature Setting Range: 30–55°C

Preset Temperatures: 38°C, 40°C and 42°C

Control Functions: Mode, Temperature Down, Temperature Up and Power

Power Parameter Configuration: Firmware-Configurable, up to 8.5 kW

Touch Panel Compatibility: 4 mm Glass Panel or 2 mm Plastic Panel

Temperature Sensor: 50K NTC

Flow Activation Threshold: 1.4 L/min

Heating Shutoff Threshold: 1.2 L/min

Buzzer Frequency: 2.5 kHz

Operating Temperature: -15°C to 65°C

Operating Humidity: 10–95% RH

Wide-Voltage Power Supply Design

The tested configuration uses an 85–280 VAC switch-mode power supply, helping the controller adapt to markets with different voltage conditions.

During internal sample validation, the controller operated continuously at 280 VAC for eight hours without abnormality. A transformer-based 180–265 VAC configuration can also be developed for projects with different cost, structure or power-supply requirements.

The operating voltage configuration should be selected according to the final appliance design and target-market electrical standards.

Flexible Temperature and Power Settings

Users can adjust the target water temperature from 30°C to 55°C in 1°C steps. The Mode key also provides quick access to 38°C, 40°C and 42°C temperature presets.

Pressing and holding the Temperature Up or Temperature Down key for more than one second enables continuous adjustment. Every valid key operation produces one audible beep for clear user feedback.

The firmware supports configurable heater power parameters up to 8.5 kW. Available power levels can be adapted to the customer’s heating system and product requirements.

The PCBA parameter does not independently determine or limit the appliance’s actual heating power. Final rated power depends on the heating element, power components, wiring, terminals, thermal design and complete-appliance configuration.

Touch-Control Panel Compatibility

The control interface supports operation through a 4 mm glass panel or a 2 mm plastic panel. The keys are designed for individual light-touch operation and do not require sliding gestures.

The key layout, panel graphics, temperature presets, display content and operating logic can be customized to match the customer’s enclosure and user-interface design.

Intelligent Display and Operating Feedback

When the controller is powered on, the buzzer sounds once and all display segments illuminate for approximately one second. This sequence provides a basic visual and audible self-check before the controller enters standby mode.

The display can present:

- Set water temperature

- Outlet water temperature

- Water-flow status

- Dynamic heating status

- Flame and circular heating indicators

- Standby and operating conditions

- Fault-code information

The display automatically enters sleep mode when no water flow or user operation is detected. It wakes up when water flow is detected or a control key is pressed, helping provide a clean and energy-efficient user interface.

Water-Flow Activation

The reference heating activation threshold is 1.4 L/min. When the water flow falls to approximately 1.2 L/min, the controller stops heating.

This flow-based control logic helps prevent heating under insufficient water-flow conditions. The thresholds can be adjusted after engineering evaluation according to the flow sensor, water path, heating power and intended application.

Automatic Temperature Learning and Parameter Memory

The PCBA supports inlet and outlet water-temperature monitoring through 50K NTC temperature sensors.

Its temperature-control software includes automatic learning and calibration functions. The controller can adjust its control parameters according to temperature feedback, water flow, heating power and the thermal characteristics of the complete appliance.

The controller also stores the selected temperature and power settings. After power-on, the system defaults to the off state while retaining the previously configured parameters.

Temperature-Control Performance

During sample testing, the inlet water temperature was 26°C and the flow rates were set to 1.5 L/min and 3.0 L/min.

After completing the initial temperature-learning calibration, the controller reached a stable temperature within 20 seconds under the recorded test conditions.

At a flow rate of 1.5 L/min:

- 30°C setting: measured at 29–31°C

- 36°C setting: measured at 35–38°C

- 40°C setting: measured at 39–41°C

- 45°C setting: measured at 44–47°C

- 48°C setting: measured at 47–50°C

At a flow rate of 3.0 L/min:

- 30°C setting: measured at 29–31°C

- 36°C setting: measured at 35–37°C

- 40°C setting: measured at 39–41°C

- 45°C setting: measured at 44–46°C

- 48°C setting: measured at 47–49°C

Actual temperature accuracy and stabilization time depend on the inlet water temperature, flow rate, heating power, sensor position and complete water-path design. Final performance should therefore be verified using the customer’s complete appliance prototype.

Multiple Safety-Protection Functions

The instant electric water heater control board integrates several protection and fault-diagnostic functions.

Over-Temperature Protection

When the detected water temperature reaches 63°C or above, the controller stops heating and activates an alarm. Heating can resume after the temperature drops to 50°C.

Leakage-Current Protection

The controller supports leakage-current detection and leakage-circuit self-testing. If an abnormal condition is detected, heating is disabled and an alarm is activated.

Outlet Temperature Sensor Protection

If the outlet temperature sensor is open or short-circuited, the controller stops heating and activates an alarm. It can automatically recover after the fault is corrected.

Inlet Temperature Sensor Diagnostics

An open or short circuit in the inlet temperature sensor activates a fault alarm. The temperature-control parameters can be relearned after the appliance is powered off, cooled and restarted.

Communication Fault Protection

If a communication fault occurs between the control sections, heating is disabled and an alarm is activated. The controller can automatically recover after normal communication is restored.

Environmental and Reliability Validation

The specified operating temperature range is -15°C to 65°C, while the operating humidity range is 10–95% RH.

During internal sample testing, the PCBA completed the following validation:

- Eight hours of continuous operation at 280 VAC

- Eight hours of operation at 65°C and 90% RH

- Dielectric withstand testing at 1800 V and 5 mA for one minute

- Thirty fluorescent-lamp switching cycles at intervals of 0.5–3 seconds

No abnormal operation was recorded during these sample tests.

These results represent internal sample validation rather than independent EMC, electrical-safety or complete-appliance certification. Certification requirements should be determined according to the customer’s product and destination market.

Typical Applications

This instant electric water heater PCBA can be used in:

- Residential instant electric water heaters

- Commercial point-of-use water heaters

- Kitchen and washbasin hot-water appliances

- Compact water heaters for apartments and dormitories

- Hotel and rental-property hot-water equipment

- Glass-panel or plastic-panel touch-control water heaters

- Water heaters requiring configurable power up to 8.5 kW

- Custom temperature-controlled heating appliances

Custom PCBA Development and Manufacturing

Foshan Shunde SunSam Electronic Co., Ltd. has 15 years of experience in custom PCBA development and manufacturing. Water heater control boards are one of our core product categories.

Our one-stop OEM and ODM services include:

- Hardware and firmware evaluation

- Circuit and PCB design support

- Component sourcing

- Prototype production

- SMT assembly

- Wave soldering

- Firmware programming

- ICT and FCT testing

- Functional verification

- Material and production traceability

- Mass-production support

The operating voltage, key layout, display content, temperature range, power parameters, flow thresholds, sensor specifications, fault codes and protection logic can be customized after engineering evaluation.

Start Your Custom Water Heater PCBA Project

Customers can provide an existing sample, BOM, Gerber files, schematic, enclosure drawing or functional specification for evaluation.

To prepare an accurate PCBA solution and quotation, we recommend providing the following information:

- Target operating voltage

- Heating-element voltage and rated power

- Required temperature range

- Water-flow sensor specifications

- Temperature-sensor specifications

- Display and key layout

- Enclosure dimensions

- Target-market testing requirements

- Estimated order quantity

- Project schedule

Contact SunSam to discuss your instant electric water heater PCBA requirements. Our engineering and production teams can support your project from initial evaluation and prototype development to functional testing and volume manufacturing.