Introduction
This manual provides comprehensive instructions for the safe installation, operation, and maintenance of your MIZUDO Gen 2 Indoor Tankless Water Heater, Model FDG-CS120BW-LP. Please read this manual thoroughly before installation and retain it for future reference. Proper installation and adherence to these instructions are crucial for optimal performance and safety.
Important Safety Information
Your MIZUDO tankless water heater is designed with multiple safety features. It is UL listed and CSA certified, meeting all US safety codes. However, improper installation, operation, or maintenance can lead to serious injury or property damage. Always follow these guidelines:
- Professional Installation: Installation must be performed by a qualified professional in accordance with all local and national plumbing and electrical codes.
- Indoor Use Only: This model is designed exclusively for indoor installation.
- Propane Fuel: Ensure the unit is connected to a liquid propane (LP) gas supply only.
- Ventilation: Proper venting is critical to prevent carbon monoxide poisoning. Ensure the venting system is correctly installed and maintained.
- Altitude Considerations: Be aware that performance may be affected at altitudes above 2000 feet (approximately 610 meters). Consult MIZUDO support if installing at higher elevations.
- Safety Protections: The unit includes windproof, waterproof, leakage protection, overheat protection, anti-freeze protection, and dry-combustion protection. Do not bypass or tamper with these features.
Figure 1: Overview of MIZUDO Tankless Water Heater Safety Protections. These features are integrated to ensure safe and reliable operation.
Product Overview
The MIZUDO Gen 2 Indoor Tankless Water Heater (Model FDG-CS120BW-LP) provides on-demand hot water with advanced temperature control. This unit is designed for indoor installation and operates on liquid propane.
Figure 2: MIZUDO Indoor Tankless Water Heater (Model FDG-CS120BW-LP).
Key Features:
- Constant Temperature Control: Self-modulating system with gas proportional valve, water volume servo, and built-in chip maintains water temperature within ±1°F.
- High Capacity: Delivers up to 5.1 GPM (Gallons Per Minute) with 120,000 BTU heating power, suitable for 2-3 simultaneous fixtures.
- Energy Efficient: Heats water only when needed, reducing standby waste and potentially saving up to 20% on gas bills. UEF > 0.81.
- Comprehensive Safety: Equipped with multiple protections including anti-freezing, overheat, leakage, and dry-combustion.
- Compact Design: Dimensions of 22.76 x 14.57 x 7.0 inches for indoor wall-mounted installation.
Setup and Installation
This section outlines the general steps for installing your MIZUDO tankless water heater. It is imperative that installation is performed by a licensed professional to ensure compliance with all local and national codes.
1. Pre-Installation Checklist:
- Verify that the installation location is indoors and protected from freezing temperatures.
- Confirm that the gas supply is Liquid Propane (LP).
- Ensure adequate ventilation and proper venting materials are available.
- Check that the electrical supply is 120V AC.
- Confirm water inlet and outlet connections are 3/4" NPT.
- Acquire necessary accessories not included: a valve kit and a vent kit.
2. Mounting the Unit:
The unit is designed for wall mounting. Use the provided screw pack and perforated paper template for accurate placement. Ensure the mounting surface is structurally sound to support the unit's weight (approximately 30.6 lbs).
Figure 3: Installation Diagram and Dimensions.
3. Connecting Water and Gas Lines:
- Connect the cold water supply to the water inlet (3/4" NPT).
- Connect the hot water outlet to your home's hot water plumbing (3/4" NPT).
- Connect the liquid propane gas supply to the gas inlet (3/4" NPT). Ensure all gas connections are leak-tested.
4. Venting:
Install the appropriate vent kit according to manufacturer instructions and local codes to safely exhaust combustion byproducts.
5. Electrical Connection:
Plug the unit into a standard 120V AC outlet. The unit consumes 37 Watt-hours.
Operating Instructions
Once properly installed and all connections are verified, operating your MIZUDO tankless water heater is straightforward.
1. Initial Startup:
- Ensure the gas supply valve is open.
- Open a hot water faucet in your home to allow water to flow through the unit. This purges air from the system.
- Plug in the unit. The LED display will illuminate.
- The unit will detect water flow and initiate the heating process. You may hear the igniter and burner activate.
2. Temperature Adjustment:
Use the controls on the LED screen to set your desired hot water temperature. The unit's advanced temperature control system will automatically adjust gas flow and water volume to maintain a consistent temperature, typically within ±1°F of your setting.
Figure 4: Internal Components for Temperature Control.
3. Normal Operation:
The unit will only consume gas when hot water is being demanded. When hot water is turned off, the unit will cease operation, saving energy.
Maintenance
Regular maintenance ensures the longevity and efficient operation of your MIZUDO tankless water heater. Always disconnect power and shut off the gas supply before performing any maintenance.
1. Annual Flushing:
To prevent mineral buildup (scaling) in the heat exchanger, it is recommended to flush the unit annually with a descaling solution. This is especially important in areas with hard water. The unit features an anti-scale design in its heating chamber, but regular flushing is still beneficial.
2. Inspect Gas and Water Connections:
Periodically check all gas and water connections for leaks or corrosion. Address any issues promptly.
3. Venting System Inspection:
Inspect the venting system for any blockages, damage, or disconnections. Ensure proper airflow and exhaust.
4. Clean Exterior:
Wipe down the exterior of the unit with a soft, damp cloth. Do not use abrasive cleaners.
Troubleshooting
This section provides solutions for common issues. For complex problems or error codes not listed, please contact MIZUDO customer support.
| Problem | Possible Cause | Solution |
|---|---|---|
| No hot water / Unit not turning on | No gas supply, no water flow, power disconnected, error code displayed. | Check gas valve, ensure water is flowing through a hot water faucet, verify power connection. Consult manual for specific error codes. |
| Inconsistent hot water / Water turns cold | Insufficient water flow, gas pressure issues, mineral buildup, high altitude effects. | Ensure adequate water flow (check for multiple fixtures running). Check gas supply and pressure. Consider annual flushing for mineral buildup. Note: Operation at altitudes above 2000 feet may affect performance; contact support for guidance. |
| Low hot water temperature | Temperature setting too low, cold inlet water temperature, excessive flow rate. | Adjust temperature setting on the LED display. Reduce hot water flow rate if inlet water is very cold. Refer to the selection guide (Figure 5) for GPM vs. temperature rise. |
| Unit making unusual noises | Mineral buildup, loose components, fan issues. | Perform annual flushing. If noise persists, contact MIZUDO support. |
Figure 5: Tankless Water Heater Selection Guide (GPM vs. Temperature Rise).
Specifications
Detailed technical specifications for the MIZUDO FDG-CS120BW-LP Tankless Water Heater.
| Feature | Specification |
|---|---|
| Brand | MIZUDO |
| Model Number | FDG-CS120BW-LP |
| Product Dimensions (W x H x D) | 14.57" x 22.76" x 7.0" |
| Item Weight | 30.6 pounds |
| Fuel Type | Liquid Propane (LP) |
| Maximum Flow Rate | 5.1 Gallons Per Minute (GPM) |
| Heat Output | 120,000 BTU |
| Electrical Power | 120 Volts (AC), 37 Watt-hours |
| Maximum Temperature | 121 Degrees Fahrenheit |
| Maximum Operating Pressure | 150 PSI |
| Efficiency | Energy Efficient (UEF > 0.81) |
| Mounting Type | Wall Mounted |
| Certifications | UL Listed, CSA Certified |
| Included Components | Gas Water Heater x 1, Manual x 1, Perforated Paper x 1, Assembly Kit x 1, Warranty Card x 1 |
Figure 6: Specifications and Included/Required Accessories.
Warranty and Support
Warranty Information:
MIZUDO provides a 2-year warranty for the entire unit and a 5-year warranty for the oxygen-free copper heat exchanger. This warranty covers defects in materials and workmanship under normal use and service. Please retain your proof of purchase for warranty claims.
Customer Support:
For technical assistance, troubleshooting, or warranty inquiries, please contact MIZUDO customer support:
- Phone: (781)-887-0291
- Email: service@mizudo.com
Our support team is available to assist you with any questions or concerns regarding your MIZUDO tankless water heater.