1. Introduction
Thank you for choosing the MIZUDO NG Sealed Gas Water Heater. This appliance is designed to provide instant hot water efficiently and safely for your home. Featuring a low NOx burner, high energy efficiency, and a user-friendly LED display, this water heater ensures a comfortable and reliable hot water supply. Please read this manual thoroughly before installation and operation to ensure proper use and maintenance.

Image 1.1: MIZUDO NG Sealed Gas Water Heater in a bathroom setting.
2. Safety Information
Your safety is paramount. This appliance must be installed and serviced by a qualified professional in accordance with all local codes and regulations. Failure to follow these instructions could result in fire, explosion, property damage, personal injury, or death.
- Gas Leak Protection: The unit is equipped with features to detect and prevent gas leaks.
- CO Intoxication Prevention: Designed to minimize the risk of carbon monoxide buildup.
- Anti-freeze Protection: Helps prevent damage from freezing temperatures.
- Over-temperature Protection: Automatically shuts off if water temperature exceeds safe limits.
- Over-pressure Protection: Safeguards against excessive water pressure.
- Dry Burn Prevention: Prevents the unit from operating without water, protecting components.
- Low NOx Emissions: Features a low emission burner for environmental safety.
Important Note: The flue exhaust system required for installation is not included with the heater and must be purchased separately.

Image 2.1: Comprehensive safety features of the MIZUDO water heater.
3. Product Overview
3.1 Key Features
- Low NOx Burner: High efficiency and energy saving, safe and reliable.
- Oxygen-Free Copper Antibacterial Water Tank: Anti-corrosive, leak-proof, rapid thermal conductivity, high energy efficiency, and long lifespan.
- Sealed Chamber Instant Gas Heater: Compatible with solar installations, easy to install.
- Smart Zone Thermostat: Maintains a constant water temperature even when multiple outlets are in use.
- Latest Generation Autonomous Gas Proportion Regulator: Ensures precise temperature control.
- Smooth Electronic Ignition: Automatic low-pressure electronic ignition, works with minimum water pressure of 0.1 bar.
- Multifunctional LED Display: Easy to use, shows water temperature and operational status.
3.2 Internal Components
The MIZUDO water heater is built with optimized materials and advanced components for superior performance and durability.

Image 3.1: Internal components of the MIZUDO water heater.
- Water Sensor: Detects water flow and temperature.
- Gas Valve: Controls gas supply to the burner.
- Heat Exchangers: Efficiently transfer heat to the water.
- Smart Chip: Manages and optimizes the heater's functions.
4. Setup and Installation
Installation must be performed by a certified technician. Ensure all local codes and regulations are met.
4.1 Tools Required for Installation
The following tools are typically required for installation and are not included with the product:
- Electric Drill
- Hammer
- Adjustable Wrench
- Screwdriver

Image 4.1: Tools needed for installation.
4.2 Product Dimensions and Connections
Refer to the diagram below for product dimensions and connection points.

Image 4.2: Product dimensions and connection details.
- Gas Connection: 1/2"
- Cold Water Connection: 1/2"
- Hot Water Connection: 1/2"
- Flue Connection: Ø 60/100 mm
4.3 Flue Exhaust System
The flue exhaust system is critical for safe operation and must be installed correctly. It is not included and must be purchased separately.

Image 4.3: Flue installation instructions.
- The exhaust pipe can be installed on the side.
- The exhaust pipe can be installed on the rear.
- The exhaust pipe should not exceed 3 meters in length.
4.4 Installation Locations
This sealed gas water heater can be installed in various enclosed spaces within your home, such as the bathroom, kitchen, or balcony, provided proper ventilation and flue requirements are met.

Image 4.4: Examples of water heater installation in a bathroom, kitchen, and balcony.

Image 4.5: Diagram illustrating installation in various enclosed spaces.
5. Operating Instructions
5.1 Initial Startup
- Ensure the gas supply valve is open.
- Open a hot water tap. The electronic ignition system will automatically activate the burner.
- The LED display will show the current water temperature.
5.2 Temperature Adjustment
Use the controls on the LED display to adjust the desired water temperature. The smart thermostat will maintain a constant temperature, providing stable and comfortable hot water.

Image 5.1: LED display for temperature control.
5.3 Instant Hot Water Delivery
The unit provides instant hot water at a flow rate of 11 liters per minute, eliminating waiting times.

Image 5.2: Illustration of instant hot water delivery.
5.4 Low Water Pressure Operation
The electronic ignition system allows the heater to function effectively even with a minimum water pressure of 0.1 bar, ensuring hot water availability in low-pressure environments.
6. Maintenance
Regular maintenance is crucial for the longevity and efficient operation of your MIZUDO gas water heater. It is recommended to have the appliance inspected and serviced annually by a qualified technician.
- Cleaning: Keep the exterior of the unit clean. Do not use abrasive cleaners.
- Ventilation: Ensure the area around the water heater is clear and well-ventilated. Do not obstruct the air intake or exhaust vents.
- Flue System Check: Regularly inspect the flue exhaust system for any blockages, damage, or leaks.
- Water Connections: Check for any signs of leaks at the water inlet and outlet connections.
- Gas Connections: Periodically check gas connections for any signs of leaks (e.g., using a soap solution).
- Professional Service: For internal cleaning, component checks, and burner adjustments, always consult a professional.
7. Troubleshooting
If you encounter issues with your water heater, refer to the following basic troubleshooting steps. For complex problems or error codes, contact customer support or a qualified technician.
- No Hot Water:
- Check if the gas supply is open.
- Ensure water pressure is sufficient (minimum 0.1 bar).
- Verify the power supply to the unit.
- Check if the LED display shows any error codes.
- Inconsistent Water Temperature:
- Ensure the desired temperature is set correctly on the LED display.
- Check for adequate water flow.
- If the issue persists, a professional inspection of the smart thermostat or gas regulator may be needed.
- Gas Odor:
- IMMEDIATELY turn off the gas supply to the unit.
- Open windows and doors for ventilation.
- Do not operate any electrical switches or appliances.
- Evacuate the premises and contact your gas provider and a qualified technician from a safe location.
- Error Codes on LED Display:
- Consult the full product manual (if available) for specific error code meanings.
- Contact customer support with the error code for assistance.
8. Specifications
| Feature | Specification |
|---|---|
| Manufacturer | MIZUDO |
| Model Number | PB1121D-001A-01-XXA-NG |
| Dimensions (L x W x H) | 72 x 41 x 26 cm |
| Weight | 13.5 kg |
| Capacity | 11 Liters |
| Flow Rate | 11 Liters per hour (Note: This is likely a typo in source data, usually L/min for water heaters) |
| Power Source | Natural Gas (NG) |
| Heat Output | 5 Kilowatts |
| Efficiency Rating | A |
| Special Features | LED Display |
| Material | Alloy Steel |
| Style | 11L NG Sealed |
9. Warranty and Support
MIZUDO is committed to product quality. If you experience any issues with the quality of your product, please contact us. We provide service in accordance with our warranty policy. You can reach us by phone, email, or message.
Please refer to your purchase documentation or the official MIZUDO website for specific warranty terms and contact information.





