1. Introduction
The HAKINAKU HD18 is a plug-in 5-in-1 detector designed to monitor your environment for carbon monoxide (CO) and combustible gases. It also provides real-time readings for temperature and humidity, and features a built-in backup battery for continuous operation during power outages. This device offers enhanced home safety by integrating multiple detection capabilities into a single unit.

Image: HAKINAKU HD18-CG detector plugged into an outlet, with a family in the background, illustrating its 10+ year lifespan and home safety benefits.
2. Safety Information
Please read all instructions carefully before installation and use. Failure to follow these instructions may result in property damage, injury, or death.
- This device is intended for residential use.
- Do not paint the detector. Paint can clog the sensor openings and prevent the unit from functioning properly.
- Do not block the ventilation openings on the detector.
- Test the detector weekly to ensure proper operation.
- The detector should be installed in a location where the alarm can be heard by all occupants.
- Carbon Monoxide (CO) is an odorless, colorless, and poisonous gas. This detector is designed to alert you to the presence of CO.
- Combustible Gases (such as natural gas, propane, methane) are flammable and can cause explosions. This detector is designed to alert you to their presence.
- This device is not a substitute for proper installation, use, and maintenance of fuel-burning appliances, including appropriate ventilation and exhaust systems.
3. Product Features
- 5-in-1 Detection: Integrates carbon monoxide, combustible gas, temperature, humidity sensors, and a backup battery.
- Plug-in Design: Compatible with 110V to 240V AC outlets for easy installation.
- Built-in 1000mAh Backup Battery: Provides approximately 12 hours of operation during power outages. Rechargeable lithium battery design eliminates the need for disposable battery replacements.
- 2.1-inch HD Screen: Displays real-time data including CO ppm, combustible gas warning icon, humidity, temperature, CO indicator, plug status, and alarm status.
- Audible and Visual Alerts: Features an 85 dB alarm sound and dynamic data display on the HD screen for effective alerts.
- Dual Charging Options: Supports both plug-in charging and Type-C USB charging (cable not included). This allows for portable use.

Image: Close-up of the HAKINAKU HD18-CG detector's screen, highlighting its five independent sensors: carbon monoxide, combustible gas, humidity, temperature, and backup battery.

Image: Illustration showing the HAKINAKU HD18-CG detector plugged into an outlet next to a graphic of a 1000mAh battery, emphasizing its built-in backup battery and charging features.
4. Package Contents
Verify that all items are included in your package:
- 1 x HAKINAKU HD18 4-in-1 CO & Gas Detector
- 1 x User Manual
5. Setup
The HAKINAKU HD18 detector is designed for simple plug-and-play operation.
- Choose a Location: Select an AC outlet in areas such as bedrooms, kitchens, living rooms, or basements. For optimal CO detection, place the detector at chest height. For combustible gas, place it closer to the floor if the gas is heavier than air (e.g., propane) or closer to the ceiling if lighter than air (e.g., natural gas). Avoid placing near windows, doors, or ventilation openings that could interfere with readings.
- Plug In: Insert the detector into a standard 110V to 240V AC outlet.
- Calibration: The detector will automatically begin a self-calibration process upon first power-up. This typically takes a few minutes. During this time, the screen may display a countdown or initialization sequence.
- Ready for Use: Once calibration is complete, the screen will display real-time CO ppm, gas status, temperature, and humidity readings, indicating the device is operational.
6. Operating Instructions
6.1. HD Screen Display Overview
The 2.1-inch HD screen provides a clear, real-time view of environmental data and device status.

Image: Detailed diagram of the HAKINAKU HD18-CG detector's HD screen display, labeling all icons and buttons including power, screen brightness, buzzer, test, CO ppm, gas icon, temperature, and humidity.
- CO PPM: Displays the current carbon monoxide concentration in parts per million.
- GAS Icon: Indicates the presence and concentration level of combustible gas.
- Temperature: Shows the ambient temperature.
- Humidity: Shows the ambient humidity level.
- Battery Level: Indicates the charge status of the built-in backup battery.
- Plug Icon: Indicates if the device is connected to AC power.
- Alarm Status: Visual indicators for CO and gas alarms.
6.2. Button Functions
- Power Button:
- Short press: Turns the device on or off.
- Screen Brightness Button:
- Short press: Changes the screen brightness.
- Long press: Changes the temperature unit (Celsius/Fahrenheit).
- Buzzer Button:
- Short press: Turns the buzzer (audible alarm) on or off.
- Long press: Rotates the screen display (0, 90, 180, or 270 degrees).
- TEST Button (Self-test):
- Short press: Initiates a self-test of the device, including the alarm sound and display.
6.3. Alarm Functions
The detector provides distinct audible and visual alarms for carbon monoxide and combustible gas.
Carbon Monoxide (CO) Alarm:
- 0-50 ppm: No alarm. The carbon monoxide icon remains green.
- 51-200 ppm: The device sounds an audible alarm every 3 minutes. The carbon monoxide icon turns yellow and blinks.
- 201-999 ppm: The device sounds continuous audible alarms. The carbon monoxide icon turns red and blinks.
Combustible Gas Alarm:
- No Combustible Gas: No alarm. The combustible gas icon remains green.
- Low and Medium Concentrations: The device sounds an audible alarm every 3 minutes. The combustible gas icon turns yellow and blinks.
- High Concentrations: The device sounds continuous audible alarms. The combustible gas icon turns red and blinks.
6.4. Battery Information
The HD18 features a built-in 1000mAh rechargeable lithium-ion battery.
- The battery provides approximately 12 hours of emergency operation during power outages.
- The battery automatically recharges when the device is plugged into an AC outlet.
- For portable use, the device can also be charged via a Type-C USB cable (not included).
7. Maintenance
Regular maintenance ensures the detector operates effectively.
- Weekly Test: Press the TEST button weekly to verify the alarm sound and display functionality.
- Cleaning: Gently clean the exterior of the detector with a soft, damp cloth. Do not use cleaning agents, solvents, or harsh chemicals. Avoid spraying cleaners directly onto the unit. Do not block the sensor openings.
- Battery Check: The battery level indicator on the HD screen will show the charge status. Ensure the device is plugged in regularly to keep the backup battery charged.
- Avoid Obstructions: Ensure that nothing obstructs the detector's ventilation openings.
8. Troubleshooting
If you encounter issues with your HAKINAKU HD18 detector, refer to the following common problems and solutions:
| Problem | Possible Cause | Solution |
|---|---|---|
| No display/Device not turning on | Not plugged in; Power outage; Battery depleted | Ensure device is securely plugged into a working outlet. Check household circuit breaker. Allow backup battery to charge. |
| Alarm sounds intermittently or continuously | Presence of CO or combustible gas; False alarm; Sensor malfunction | If CO or gas is suspected: Ventilate the area immediately, evacuate, and call emergency services. Do not re-enter until safe. If no gas is present, test the unit. If alarm persists, contact support. |
| TEST button does not activate alarm | Device malfunction; Low battery | Ensure device is plugged in and battery is charged. If still unresponsive, the unit may be faulty and needs replacement. |
| Inaccurate temperature/humidity readings | Placement near heat/cold source; Sensor interference | Relocate the detector away from direct sunlight, vents, or appliances that emit heat or cold. |
9. Specifications
| Feature | Specification |
|---|---|
| Model Number | HD18 |
| Power Source | AC 110V-240V |
| Backup Battery | 1000mAh Lithium Ion (included) |
| CO Detection Range | 0-999 ppm |
| Combustible Gas Detection | Natural gas, propane, methane, coal gas, gasoline, hexane, butane, benzene, ethylene oxide, acetylene, LPG, LNG, etc. |
| Alarm Loudness | >85 dB |
| Display | 2.1-inch HD Screen |
| Dimensions | 3.93 x 1.02 x 2.55 inches |
| Item Weight | 3.52 ounces |
| Operating Temperature | Refer to product packaging for specific range |
| Operating Humidity | Refer to product packaging for specific range |
10. Warranty and Support
HAKINAKU products are designed for reliability and performance. For warranty information or technical support, please refer to the product packaging or contact HAKINAKU customer service through their official channels. You can also visit the HAKINAKU Store on Amazon for more information.




