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Natural Gas Tankless Water Heater, MIZUDO Up to 5.1 GPM, 120,000 BTU, CSA Certified, Indoor Installation Instant Hot Water Heater, Gen 2

  • Based on 114 reviews
Condition: New
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$549.00 Why this price?
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Availability: In Stock.
Fulfilled by Amazon

Arrives Saturday, May 3
Order within 14 hours and 2 minutes
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Material Type: 5.1GPM | 120,000BTU


Style: Natural Gas


Features

  • Quality Certification: It has passed CSA certification and has protection functions such as overheating protection and accidental flameout protection. It meets national safety standards and protects the safety of you and your family in many aspects.
  • Endless Hot Water: No need to wait for the water tank to heat up, it provides endless hot water 24 hours a day, allowing you and your family to use a steady stream of hot water at multiple locations at any time.
  • Precise Temperature Control: The internal movement can keenly sense changes in water temperature and intelligently adjust the water temperature to ensure that the temperature difference is within 1F.
  • Quality Material: The built-in oxygen-free copper water tank has excellent thermal conductivity and anti-corrosion effects, allowing the water heater to have a longer service life and achieve durability.
  • Product Information: Dimensions are H 22.8'' x W 14.6'' x D 7.0''. Compared with tank water heaters, it can save more than 50% of space. The interface is universal 3/4"NPT, which is easy to install.

Brand: MIZUDO


Product Dimensions: 14.57"W x 22.76"H


Special Feature: Comfortech 2nd Generation, Built-in Water Proportional Valve 2.0, 2&5 Years Warranty, 24/7 Customer Service, CSA Certified See more


Color: White


Wattage: 37 Watt-hours


Brand: ‎MIZUDO


Product Dimensions: ‎14.57"W x 22.76"H


Special Feature: ‎Comfortech 2nd Generation, Built-in Water Proportional Valve 2.0, 2&5 Years Warranty, 24/7 Customer Service, CSA Certified


Color: ‎White


Wattage: ‎37 Watt-hours


Voltage: ‎120 Volts (AC)


Maximum Flow Rate: ‎5.1 Gallons Per Minute


Heat Output: ‎120000 BTU per Hour per Foot per Degree Fahrenheit


Efficiency: ‎High


Maximum Operating Pressure: ‎150 Pound per Square Inch


Mounting Type: ‎Wall


Is Electric: ‎No


Manufacturer: ‎Mizudo


Item Depth: ‎7 inches


Item Weight: ‎29.9 pounds


Country of Origin: ‎China


Item model number: ‎FDG-CS120BW-NG


Item Package Quantity: ‎1


Special Features: ‎Comfortech 2nd Generation, Built-in Water Proportional Valve 2.0, 2&5 Years Warranty, 24/7 Customer Service, CSA Certified


Included Components: ‎Gas Water Hetaer x 1, Manual x 1, Perforated Paper x 1, Assembly Kit x 1, Warranty Card x 1


Batteries Included?: ‎No


Batteries Required?: ‎No


Date First Available: January 13, 2024


Frequently asked questions

If you place your order now, the estimated arrival date for this product is: Saturday, May 3

Yes, absolutely! You may return this product for a full refund within 30 days of receiving it.

To initiate a return, please visit our Returns Center.

View our full returns policy here.

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Top Amazon Reviews


  • Works well
Material Type: 5.1GPM | 120,000BTU Style: Natural Gas
The heater is easy to install. Heat up water instantly and so far is working well without any problem.
Reviewed in the United States on January 8, 2025 by TL

  • Works Great!
Material Type: 4.0 GPM | 90,000BTU Style: Natural Gas
I have a small 1200ft house with just my fiancé and I. This works great for our needs! Do research on the install as it’s not your normal water heater connections. I placed a larger 4” metal dryer vent hood through the exterior wall then routed the smaller vent pipe for the unit through it (vent pipe is smaller, 3”, so it doesn’t touch the homes walls). Water pressure is great, heat is very good, the only caveat is if your turning on and off your water (say washing your face) it’ll have to shoot out the cold water from restarting before it gets back to hot. Overall great purchase as it also should save money from not having a lite water heater 24/7. If you have hard water (I don’t) then maybe install a filter in line or flush your unit once a year with vinegar. ... show more
Reviewed in the United States on November 20, 2024 by Jordan F. Jordan F.

  • Good product
Material Type: 5.1GPM | 120,000BTU Style: Natural Gas
The first one that I ordered had some electrical defects when I hooked it up. The system continued to beep on and off constantly and would not work. I filed for a replacement through Amazon and it was a good interaction. I received a replacement model which works perfect!! It's quiet and heats water in seconds.. I'd buy again! ... show more
Reviewed in the United States on December 20, 2024 by Brett

  • Surprisingly small and light weight.
Material Type: 3.6 GPM | 80,000BTU Style: Natural Gas
My five-star rating could change as this unit has only been up and running for a week. It was on sale for an irresistible price so I took a chance. It is rated higher than others at its non-sale price point, but it lacked the number of feedbacks that I would normally like to see. I eliminate dumb 1 and two star ratings but still pay attention to them. At 4.3 with no issues that seemed to be a roadblock for me, it was worth a try. I live alone so 3.6 gpm is more than enough flow rate, and 80,000 btu is plenty. Even two people could be using hot water simultaneously provided those outlets are low flow imho. It responds fast for my plumbing distances and stays on point with no temperature waffling...yet. My slight lack of confidence is based on the age old "you get what you pay for" mantra, but sometimes you get a gem. Other than awkward grammar at times, the instructions were pretty clear. MAKE SURE you have a gas line that matches or exceeds the btu rating of the unit. That was not clear in the instructions ... show more
Reviewed in the United States on August 25, 2023 by Carl Baldwin

  • Not worth the trouble
Material Type: 5.1GPM | 120,000BTU (Outdoor Ins... Style: Natural Gas
I'm experiencing multiple issues with this water heater. It heats up for about a minute before turning cold, requiring us to repeatedly switch it off and on. I noticed that another customer mentioned a similar issue in their review. Additionally, there is a noticeable delay in getting hot water to the faucets throughout my home, and the unit cannot support two people showering at the same time. This is already our second unit—the first one had an electrical issue and had to be returned. Unfortunately, this replacement is also not functioning properly. Given that this is a brand-new construction home, I expected better performance. At this point, I'm seriously considering requesting assistance or a refund. ... show more
Reviewed in the United States on March 12, 2025 by Chatoya

  • Works well
Material Type: 3.6 GPM | 80,000BTU Style: Natural Gas
Get the 100k btu. You will appreciate the extra flow when the incoming water is really cold and the faster heat up time.
Reviewed in the United States on February 1, 2025 by Jim in OH

  • Arrived Fast. Easy to Install. Great Seller
Material Type: 5.1GPM | 120,000BTU Style: Natural Gas
This arrived very fast, which is good because my tank water heater died. After reading the instructions and looking at the unit I realized that the installation is very straight forward and fairly simple for any good DIY'er. The hardest part was removing my old 50 gallon Tank Water Heater. It fired up the first time and is working perfectly. I am adding a 2 Stage water prefilter in a few days to prolong the life expectancy of the unit.I only had to deal with the seller 1 Time since purchased, and they were quick to respond and solved my only issue immediately. For those that live in high altitude areas, I would recommend this unit for a 2-Bath home. Both of my showers run very well at the same time @ 6000 ft above sea level. I had to get a 1/2"NG to 3/4"NG converter and new 3/4' NG Line to connect to the unit, and am having no issues with NG Supply under heavy load. It only takes up 1/4 the space that my old water heater did. I am very pleased with the uniy, the seller and the service. :-) ... show more
Reviewed in the United States on July 22, 2024 by Amazon Customer Amazon Customer

  • Great water heater
Material Type: 5.1GPM | 120,000BTU Style: Natural Gas
this water heater works great. only complaint is if there is a power outage you must push power button on front control panel to turn it back on.
Reviewed in the United States on December 12, 2024 by sgt spicoli

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