HS-CT-36B-5KEY Instant Electric Water Heater PCBA

HS-CT-36B-5KEY Instant Electric Water Heater PCBA with AI Control

HS-CT-36B-5KEY Instant Electric Water Heater PCBA from SUNSAM gives OEM buyers a wide-voltage control platform for 3.8, 4.5 and 5.5 kW household water heaters. AI temperature adjustment, low-flow activation, five-key touch operation and fault monitoring support customized water-heating products.

The complete PCBA model is HS-CT-36B-5KEY-V1.4. A BYD control chip, switch-mode power supply, temperature sensors, water-flow detection and dynamic LED indication form the main control platform.

Wide-Voltage Input for Different Power Grids

The tested switch-mode power supply version operates from AC 85–270 V. The sample completed eight hours of continuous operation at AC 270 V without abnormal performance.

Both 50 Hz and 60 Hz operating frequencies were tested. The wide-voltage design supports instant water heater projects intended for countries with different mains-voltage and frequency conditions.

The test report also lists a transformer-based version operating from AC 180–265 V. The transformer-based and switch-mode versions represent separate hardware configurations. Customers should confirm the required version before sample production.

Three Configurable Heating-Power Settings

The HS-CT-36B-5KEY water heater control board supports three configurable power settings:

- 3.8 kW

- 4.5 kW

- 5.5 kW

Holding the AI key and 42°C key for five seconds opens the heating-power configuration menu. The controller automatically saves the selected power and exits the menu after five seconds without further operation.

Actual output cannot exceed the rated power of the connected heating element. Power components, wiring, terminals and thermal performance must match the selected configuration.

Five-Key Touch-Control Interface

The control interface contains five touch keys:

- AI

- Temperature decrease

- Power

- One-touch 42°C setting

- Temperature increase

Long-press operation on the Increase or Decrease key supports continuous temperature adjustment. An audible buzzer provides feedback during key operation and fault alarms.

The touch interface can operate through a surface-mounted 4 mm glass panel or a 2 mm plastic panel. Appliance manufacturers can therefore develop different front-panel materials and appearance designs around the same control platform.

AI Temperature Adjustment

The adjustable temperature range covers 30–52°C. AI mode automatically selects a suitable temperature-control setting according to the programmed operating logic.

Manual adjustment within ±5°C keeps AI mode active. A larger manual adjustment exits AI mode and returns control to the selected temperature setting.

The dedicated 42°C key provides quick access to a commonly used shower-water temperature. Automatic calibration and memory functions retain the constant-temperature parameters after setup.

Low-Flow Activation and Standby Control

The HS-CT-36B-5KEY Instant Electric Water Heater PCBA starts heating when the detected water flow reaches approximately 1.0 L/min. Heating stops when the flow decreases to approximately 0.8 L/min.

Low-flow activation supports water-heating systems operating under different inlet-pressure conditions. Final performance depends on the selected flow sensor, pipeline structure, heating assembly and installation environment.

When no water flow or key operation is detected for 30 seconds, the display enters sleep mode. Water flow or any key operation can wake the control system.

Dynamic LED Display

The display performs a one-second full-screen self-test after power connection. The controller then displays the current configured heating power.

After the Power key is pressed, a 5, 4, 3, 2, 1 countdown appears before heating operation begins.

The display interface supports:

- Configured heating power

- Actual outlet water temperature

- Water flow rate

- Operating status

- Brand logo

- Green leaf status icon

- Fault indication

- Three-color LED water-flow indication

Red, blue and green LEDs remain static when no water flow is detected. The three colors operate dynamically during water flow, providing a visible indication of the working status.

Temperature-Control Performance

The control system uses a 50 kΩ NTC temperature sensor for temperature measurement. Inlet and outlet temperature monitoring supports constant-temperature control and sensor fault diagnosis.

According to the sample test report, measured outlet temperatures remained within approximately ±2°C at the recorded settings. Test conditions included an inlet water temperature of 25°C and flow rates of 1.5 L/min and 3 L/min.

Recorded stabilization times ranged from approximately 6 to 20 seconds after initial temperature learning and calibration.

Recorded Temperature-Control Results

| Flow Rate | Set Temperature | Measured Temperature | Stabilization Time |

|---|---:|---:|---:|

| 1.5 L/min | 36°C | 35–37°C | 15–20 s |

| 1.5 L/min | 40°C | 40–42°C | 10–15 s |

| 1.5 L/min | 45°C | 44–46°C | 8–12 s |

| 1.5 L/min | 48°C | 48–50°C | 6–8 s |

| 3 L/min | 36°C | 36–37°C | 15–20 s |

| 3 L/min | 40°C | 39–42°C | 8–12 s |

| 3 L/min | 45°C | 44–46°C | 8–10 s |

| 3 L/min | 48°C | 47–49°C | 6–8 s |

Final temperature-control accuracy and stabilization time depend on inlet water temperature, water flow, heating capacity and the complete appliance structure.

Fault Monitoring and Protection Functions

The instant electric water heater control board supports multiple fault-monitoring and heating cut-off functions.

Available functions include:

- Outlet over-temperature protection

- Leakage current protection

- Inlet temperature sensor open-circuit detection

- Inlet temperature sensor short-circuit detection

- Outlet temperature sensor open-circuit detection

- Outlet temperature sensor short-circuit detection

- Tilt switch protection

- Zero-crossing fault monitoring

- Heating cut-off during detected faults

- Audible alarm and fault-code indication

E4 Over-Temperature Protection

When the detected temperature reaches or exceeds 65°C, E4 protection stops heating and activates the alarm. Normal operation automatically resumes after the temperature falls to 50°C.

E2 Outlet Temperature Sensor Fault

An outlet temperature sensor open-circuit or short-circuit condition stops heating and activates the alarm. Normal operation automatically resumes after the fault is cleared.

E3 Inlet Temperature Sensor Fault

An inlet temperature sensor open-circuit or short-circuit condition stops heating and activates the alarm. Normal operation automatically resumes after the fault is cleared.

HR Tilt Protection

A detected tilt switch fault stops heating and activates the alarm. Normal operation requires fault clearance and a power cycle.

Leakage Protection

The leakage protection operating range covers 15–30 mA. The tested sample recorded a leakage trip current of 26 mA. Complete-unit validation remains necessary before batch production.

Main Technical Specifications

| Parameter | Specification |

|---|---|

| Product Name | HS-CT-36B-5KEY Instant Electric Water Heater PCBA |

| Complete PCBA Model | HS-CT-36B-5KEY-V1.4 |

| Controller Chip | BYD Control Chip |

| Power Supply Design | Switch-Mode Power Supply |

| Operating Voltage | AC 85–270 V |

| Operating Frequency | 50/60 Hz |

| Configurable Heating Power | 3.8, 4.5 or 5.5 kW |

| Temperature Setting Range | 30–52°C |

| One-Touch Temperature | 42°C |

| Activation Flow Rate | 1.0 L/min |

| Shut-Off Flow Rate | 0.8 L/min |

| Temperature Sensor | 50 kΩ NTC |

| Leakage Protection Range | 15–30 mA |

| Control Interface | Five-Key Touch Control |

| Panel Compatibility | 4 mm Glass or 2 mm Plastic |

| Standby Time | 30 Seconds |

| Reported Operating Temperature | −15°C to 85°C |

| Reported Operating Humidity | 10%–95% RH |

Sample Testing and Verification

The sample test report records the following verification results:

- Eight hours of continuous operation at AC 270 V

- Eight hours of continuous operation at 85°C and 85% relative humidity

- Normal operation at both 50 Hz and 60 Hz

- No abnormal performance after 30 switching-interference cycles

- Complete-unit dielectric withstand test at 1,800 V, 5 mA for one minute

- Leakage protection trip test at 26 mA

- Constant-temperature testing at 1.5 L/min and 3 L/min

- Outlet-temperature deviation of approximately ±2°C under recorded conditions

Recorded results apply to the tested sample and stated test conditions. Final electrical, environmental and safety performance requires verification after integration into the complete water heater.

Water Heater PCBA Development and Manufacturing

Water heater PCBA projects account for approximately 70% of SUNSAM’s current PCBA production. Fifteen years of customized PCBA experience support water heater manufacturers from initial requirement analysis to prototype and batch production.

SUNSAM provides:

- Hardware circuit development

- Embedded firmware development

- Existing PCBA sample analysis

- PCB layout and PCBA redesign

- Electronic component sourcing

- SMT assembly

- DIP assembly

- Wave soldering

- Functional testing

- IPQC and IPQA inspection

- Production traceability

- Prototype and volume manufacturing

The internal traceability process can cover raw materials, work-in-process products and finished PCB assemblies. Component selection and production planning can be adjusted according to the required functions, estimated quantity and destination-market standards.

More control board solutions are available on the [SUNSAM PCBA product page](https://www.sunsampcba.com/products.html).

Applications

The HS-CT-36B-5KEY control platform can support:

- Household instant electric water heaters

- Instant electric shower water heaters

- Compact bathroom water heaters

- Wall-mounted electric water heaters

- Low-flow water-heating systems

- Wide-voltage export water heater projects

- OEM and ODM water-heating products

Customers can provide an existing PCBA sample, functional specification, heating-element information, product dimensions, wiring diagram and estimated order quantity. SUNSAM can evaluate the requirements and prepare a matching PCBA development and manufacturing proposal.

Frequently Asked Questions

What heating-power settings are available?

The current control platform supports 3.8, 4.5 and 5.5 kW settings. Final power selection depends on the heating element, wiring, terminals and thermal structure.

### What is the minimum activation flow rate?

The recorded activation flow rate is approximately 1.0 L/min. Heating stops when the flow decreases to approximately 0.8 L/min.

Does the controller support automatic temperature adjustment?

Yes. AI mode provides programmed temperature adjustment, while the dedicated 42°C key provides one-touch temperature selection.

Can the front panel be customized?

Yes. The touch interface supports 4 mm glass and 2 mm plastic panels. Key graphics, display icons, brand logos and interface layouts can be customized after technical evaluation.

Does the PCBA support tilt protection?

Yes. The HR protection function stops heating and activates the alarm when a tilt switch fault is detected.

What information is required for a quotation?

An existing sample, detailed functional specification, PCBA dimensions, wiring diagram, sensor information, target power, safety requirements and estimated order quantity can support technical and cost evaluation.

Is sample validation required before mass production?

Yes. The PCBA must be matched with the heating element, flow sensor, temperature sensors, display panel, wiring and safety components of the complete appliance. Prototype validation should be completed before batch production.