HS-NXS-SXD-CODE Rotary Water Heater PCBA

HS-NXS-SXD-CODE-P1.0 Integrated Instant Electric Water Heater PCBA with Rotary Control

The HS-NXS-SXD-CODE-P1.0 is an integrated instant electric water heater PCBA developed for appliances requiring a compact control structure, wide-voltage operation and an intuitive rotary user interface.

This all-in-one control board integrates the power-control and display-control sections on a single PCBA. Based on a 28-pin BYD control IC, it supports temperature adjustment, Celsius and Fahrenheit selection, P2–P8 configurable power levels, water-flow activation, automatic temperature learning, parameter memory and multiple fault-diagnostic functions.

SunSam can customize the hardware, firmware, display artwork, rotary interface, sensor inputs and operating logic according to the customer’s appliance structure, heating system and target market.

Key Specifications

PCBA Model: HS-NXS-SXD-CODE-P1.0

PCBA Structure: Integrated Power and Display Control Board

Control IC: BYD 28-Pin Control IC

Standard Power Supply: Switch-Mode Power Supply

Standard Input Voltage: 65–280 VAC

Optional Transformer Input: 180–280 VAC

Control Method: Rotary Knob with Power Key

Temperature Setting Range: 30–55°C

Default Temperature: 42°C

Temperature Adjustment Step: 1°C

Temperature Units: Celsius and Fahrenheit

Power-Level Settings: P2, P3, P4, P5, P6, P7 and P8

Temperature Sensor: 50K NTC

Flow Activation Threshold: 1.8 L/min

Heating Shutoff Threshold: 1.5 L/min

Water-Flow Switch: Three-Wire Flow Switch

Leakage Detection Range: 15–30 mA

Buzzer Frequency: 2.5 kHz

Operating Temperature: -15°C to 65°C

Operating Humidity: 10–95% RH

Integrated PCBA Design

The HS-NXS-SXD-CODE-P1.0 combines power and display control on one circuit board. This integrated structure can reduce internal wiring, simplify assembly and help save installation space inside the water-heater enclosure.

The board is suitable for manufacturers developing compact instant water heaters or products that require a rotary interface instead of a conventional multi-key panel.

Wide-Voltage Power Supply

The standard sample uses a switch-mode power supply with a 65–280 VAC input range. During internal validation, the controller operated continuously at 280 VAC for eight hours without abnormality.

An optional transformer-based configuration supports an input range of 180–280 VAC. The transformer configuration was tested continuously at 265 VAC for eight hours without abnormality.

The appropriate power-supply architecture can be selected according to the product structure, cost target, regional voltage conditions and complete-appliance electrical requirements.

Rotary Temperature Control

The rotary interface provides a simple method for temperature adjustment:

- Turn left to decrease the temperature

- Turn right to increase the temperature

- Each rotary step changes the temperature by 1°C

- Each valid operation produces one audible beep

The adjustable temperature range is 30–55°C, and the default initialization temperature is 42°C.

This rotary design is suitable for instant water heaters requiring a clean interface with fewer operating steps. The knob structure, graphics, display film and operating direction can be customized according to the customer’s enclosure design.

Celsius and Fahrenheit Selection

The controller supports both Celsius and Fahrenheit temperature units. Pressing and holding the Power key for approximately three seconds switches between °C and °F.

This function allows the same PCBA platform to be adapted for markets with different temperature-display preferences without redesigning the main hardware.

P2–P8 Configurable Power Levels

The firmware includes seven configurable power levels:

- P2

- P3

- P4

- P5

- P6

- P7

- P8

Pressing and holding the rotary control while turning it left for approximately three seconds opens the power-level setting interface.

P2–P8 are firmware level codes. The sample test report does not define their corresponding wattage values. The relationship between each level and the actual heater power should be configured according to the heating element, power-control components and complete-appliance design.

The actual rated power and current capacity depend on the relay or semiconductor power stage, PCB copper design, wiring, terminals, heating element and thermal-management system.

Display and Operating Feedback

When power is connected, the buzzer sounds once and all digital display segments illuminate for approximately one second. This provides a basic visual and audible self-check.

After the appliance is switched on, the display presents the outlet water temperature. The interface can also display temperature units, operating conditions, power-level information and fault codes according to the selected firmware configuration.

The current sample uses a Chinese display overlay. Display language, symbols, icons and printed artwork can be customized for international markets.

Water-Flow Activation

The reference heating activation threshold is 1.8 L/min. Heating stops when the flow drops to approximately 1.5 L/min.

The sample uses a three-wire water-flow switch. The controller coordinates the detected flow condition with the heating output to prevent normal heating operation when the water flow is insufficient.

The flow interface and thresholds can be adjusted after engineering evaluation according to the water path, sensor characteristics and heating power.

Temperature Monitoring and Automatic Learning

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

Its firmware includes automatic temperature-control learning and calibration. This allows the controller to adapt its control parameters according to water flow, inlet temperature, outlet temperature, heating power and the thermal characteristics of the complete appliance.

The selected temperature and power-level settings are stored automatically. When power is restored, the controller defaults to the off state while retaining the previously configured parameters.

Sample Temperature-Control Performance

Temperature-control testing was performed with an inlet water temperature of 26°C and flow rates of 1.5 L/min and 3.0 L/min.

After the initial temperature-learning calibration, the controller achieved temperature stabilization within 20 seconds under the recorded sample 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 inlet water temperature, flow rate, heating power, sensor position and complete water-path design. Final performance must be verified using the customer’s complete appliance prototype.

Multiple Safety and Diagnostic Functions

E1 Over-Temperature Protection

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

E2 Leakage-Current Protection

If a leakage-current fault is detected, heating is disabled and an alarm is activated. Normal operation can resume after the fault is repaired and the appliance is restarted.

The sample report specifies a leakage-detection range of 15–30 mA. The measured sample value was 24 mA using a three-wire leakage-detection coil.

The final protection threshold must be matched to the selected leakage coil and complete-appliance safety design.

E3 Inlet Temperature Sensor Fault

An open or short circuit in the inlet temperature sensor activates an alarm. The sample program indicates that heating can continue, while temperature-control relearning is required after a cold restart.

This control logic can be modified according to the customer’s safety requirements.

E4 Outlet Temperature Sensor Fault

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

Zero-Crossing Control

The firmware includes zero-crossing-related burst-fire heating control. The final detection method, fault definition and recovery logic should be confirmed according to the selected power-control circuit.

Communication Diagnostics

The firmware reserves E9 for communication-fault diagnostics. The specific heating response, alarm behavior and recovery method can be defined for the customer’s final program.

Environmental and Reliability Validation

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

The sample completed the following internal tests:

- Eight hours of continuous operation at 280 VAC with the switch-mode power supply

- Eight hours of continuous operation at 265 VAC with the transformer configuration

- 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

- Normal-temperature water-change testing

- Circulating-water temperature-control testing

No abnormal operation was recorded during these sample tests.

These results represent internal sample validation and should not be interpreted as independent EMC, electrical-safety or complete-appliance certification.

Typical Applications

The HS-NXS-SXD-CODE-P1.0 can be used in:

- Residential instant electric water heaters

- Compact point-of-use water heaters

- Kitchen and washbasin hot-water appliances

- Hotel and apartment water-heating equipment

- Rotary-control electric water heaters

- Water heaters requiring Celsius and Fahrenheit selection

- Products requiring multiple firmware power levels

- Custom temperature-controlled heating appliances

OEM/ODM 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:

- Product-function evaluation

- Hardware and firmware development

- 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

- Volume manufacturing

The input-voltage range, rotary operation, display language, temperature range, power levels, sensor parameters, flow thresholds, 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.

For an accurate technical proposal and quotation, please provide:

- Target-market voltage requirements