1. Introduction
This manual provides essential information for the safe and efficient installation, operation, and maintenance of your MIZUDO Gen 2 4.0 GPM Propane Indoor Tankless Water Heater. Please read all instructions thoroughly before installation and use. Retain this manual for future reference.
The MIZUDO Gen 2 tankless water heater is designed to provide on-demand hot water, featuring advanced temperature control and energy efficiency. It is UL listed and CSA certified, meeting all applicable US safety codes.
Figure 1: MIZUDO Gen 2 4.0 GPM Propane Indoor Tankless Water Heater.
2. Product Overview and Features
The MIZUDO Gen 2 tankless water heater offers a maximum flow rate of 4.0 Gallons Per Minute (GPM) and a heat output of 90,000 BTU, suitable for homes or apartments with 1-2 bathrooms, supporting simultaneous use of two showers and one sink.
Key Features:
- Upgraded Temperature Control: The Gen 2 model features a self-modulating system with a gas proportional valve and built-in chip, ensuring a constant temperature with fluctuations within ±1°F.
- Energy Efficiency: With a Uniform Energy Factor (UEF) greater than 0.81, this unit consumes gas only when hot water is demanded, potentially saving up to 20% on gas bills compared to traditional tank heaters.
- Comprehensive Safety Protections: Includes windproof, waterproof (IPX4), leakage, overheat, anti-freeze, dry-combustion, and flame-out protections to enhance safety and extend product lifespan.
- Durable Heat Exchanger: Equipped with an oxygen-free copper heat exchanger for efficient heat transfer and longevity.
- User-Friendly Interface: Features an LED screen for easy temperature monitoring and control.
Figure 2: Product highlights including 4.0 GPM flow and 90,000 BTU heating power, alongside CSA certification.
Figure 3: Illustration of the three major temperature control components: temperature control chip, water flow sensor, and gas regulating valve.
Figure 4: The 4.0 GPM capacity supports multiple hot water outlets simultaneously, such as a master bathroom, auxiliary bathroom, and kitchen.
3. Setup and Installation
Proper installation is crucial for the safe and efficient operation of your tankless water heater. It is recommended that installation be performed by a qualified professional.
3.1 Package Contents:
- Gas Water Heater x 1
- Instruction Manual x 1
- Perforated Paper x 1 (for mounting template)
- Assembly Kit x 1 (screws, anchors)
- Warranty Card x 1
3.2 Required Accessories (Not Included):
The following items are typically required for installation and must be purchased separately:
- Valve Kit (water shut-off valves, pressure relief valve)
- Vent Kit (appropriate for indoor propane tankless water heaters)
- Gas line fittings (3/4" NPT to appropriate size for your gas supply)
- Mounting hardware (if not using included assembly kit or for specific wall types)
Figure 5: Overview of product specifications, included accessories, and additional items required for installation.
3.3 Connection Requirements:
- Power Supply: 120 VAC, 60 Hz (standard 3-prong plug).
- Water Connections: 3/4" NPT for both water inlet and outlet.
- Gas Connection: 3/4" NPT for propane gas inlet.
Figure 6: Detailed installation diagram showing electrical and plumbing connections.
3.4 Sizing and Selection Guide:
Refer to the selection guide to ensure the unit meets your household's hot water demands based on your local ground water temperature and desired flow rates.
Figure 7: Tankless Water Heater Selection Guide. Use this chart to determine the appropriate GPM based on your inlet water temperature and desired hot water usage.
4. Operating Instructions
The MIZUDO tankless water heater is designed for straightforward operation via its integrated LED control panel.
4.1 Initial Startup:
- Ensure all water and gas connections are secure and leak-free.
- Open the water supply valves to the unit.
- Purge air from the water lines by opening a hot water faucet in your home until water flows steadily.
- Plug the unit into a grounded 120V AC outlet.
- Turn on the gas supply to the unit.
- Press the power button on the control panel.
4.2 Temperature Adjustment:
Use the 'Up' and 'Down' arrow buttons on the LED display to set your desired hot water temperature. The unit will automatically adjust its heating output to maintain this temperature.
Figure 8: LED control panel for temperature adjustment.
4.3 Precision Heating Modes:
The unit features a 4-stage precision heating mode that automatically selects the most appropriate heating level based on the season and incoming water temperature, optimizing comfort and efficiency.
Figure 9: The 4-stage precision heating mode adapts to seasonal temperature changes for optimal performance.
5. Maintenance
Regular maintenance ensures the longevity and optimal performance of your MIZUDO tankless water heater.
5.1 Anti-Freezing Protection:
The unit is equipped with automatic anti-freezing protection. However, in extremely cold climates or during prolonged power outages, additional measures may be necessary to prevent freezing. Consult a professional for advice specific to your climate.
5.2 General Care:
- Keep the area around the water heater clear of obstructions.
- Periodically inspect gas and water connections for any signs of leaks.
- Ensure the ventilation system is clear and unobstructed.
- For optimal performance and to prevent scale buildup, consider annual flushing of the unit, especially in areas with hard water.
Figure 10: The unit incorporates multiple safety features, including anti-freeze and scale-proof heating chamber design, which contribute to its durability and safety.
6. Troubleshooting
If you encounter issues with your MIZUDO tankless water heater, refer to the following common problems and solutions. For complex issues, contact customer support.
| Problem | Possible Cause | Solution |
|---|---|---|
| No hot water | No power, no gas, water supply off, unit error code | Check power connection, gas supply, water valves. Refer to LED display for error codes and consult manual. |
| Water not hot enough | Temperature setting too low, high flow rate exceeding capacity, cold inlet water temperature | Increase temperature setting. Reduce simultaneous hot water usage. Refer to selection guide for GPM limits. |
| Unit cycles on/off frequently | Low water flow, air in system, minor leak | Ensure adequate water flow. Purge air from lines. Check for leaks. |
| Error code displayed | Internal fault, sensor issue, external condition | Note the error code and consult the full user manual or contact MIZUDO customer support. |
7. Specifications
| Attribute | Detail |
|---|---|
| Brand | MIZUDO |
| Model Number | FDG-CS90AG-LP |
| Product Dimensions | 16.3"W x 25"H x 7"D (approximate) |
| Color | White |
| Power Source | Propane Gas, 120V AC (for electronics) |
| Wattage | 20 Watt-hours |
| Voltage | 120 Volts (AC) |
| Maximum Flow Rate | 4 Gallons Per Minute |
| Heat Output | 90,000 BTU per Hour |
| Efficiency | UEF > 0.81 (Energy Efficient) |
| Maximum Operating Pressure | 150 Pound per Square Inch |
| Mounting Type | Wall |
| Item Weight | 29 pounds |
| Certifications | UL Listed, CSA Certified |
| Special Features | 2 Years Support for Whole Unit, 5 Years Support for Heat Exchanger, Automatic Anti-Freezing Protection, Upgraded Temp Control |
8. Warranty and Support
MIZUDO stands behind the quality of its products.
8.1 Warranty Information:
- Whole Unit: 2-year support from the date of purchase.
- Heat Exchanger: 5-year support from the date of purchase.
Please retain your proof of purchase for warranty claims. The warranty does not cover damage caused by improper installation, misuse, or freezing.
8.2 Customer Support:
For technical assistance, troubleshooting, or warranty inquiries, please contact MIZUDO customer support:
- Phone: (781)-887-0291
- Email: service@mizudo.com
Figure 11: MIZUDO contact information for support.