MIZUDO Natural Gas Tankless Water Heater Indoor, Max 4.3 GPM 100,000 BTU CSA Certified 3/4" NPT On Demand Instant Hot Water Heater for 2-3 Fixtures Whole Family or Apartment Use
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Material Type: 4.3 GPM, 100,000 BTU, Indoor
Style: Natural Gas
Features
- Continuous Hot Water for Multi-Tasking: Mizudo tankless water heater provides hot water within 10 seconds at 4.3 GPM and 100,000 BTU, suitable for homes with bathrooms using 2-3 low-flow fixtures
- Energy Efficient Operation: On-demand heating, tankless water heater only consumes gas during use. Oxygen-free copper heat exchanger provides faster heating than standard steel models
- Third-Party Certified Safety: All tankless water heaters gas are UL listed and CSA certified to meet US safety standards for gas appliances. Includes 2-year whole unit coverage and 5-year for heat exchanger
- Integrated Protection System: This natural gas tankless water heater is provided with built-in safeguards such as freeze protection, leak detection, overheat cutoff, and wind-resistant ignition
- US Home Compatibility: The gas water heater indoor is compact 20.5 x 13.0 x 7.0 in. Natural gas powered indoor unit. Operates on 120V power with 3/4" NPT connectors. UEF >0.81
Brand: MIZUDO
Product Dimensions: 13"W x 20.5"H
Special Feature: 2 Years Support for Whole Unit, 5 Years Support for Heat Exchanger, Automatic Anti-Freezing Protection, CSA Certificated, Temp Self Modulating See more
Color: White
Voltage: 120 Volts (AC)
Brand: MIZUDO
Product Dimensions: 13"W x 20.5"H
Special Feature: 2 Years Support for Whole Unit, 5 Years Support for Heat Exchanger, Automatic Anti-Freezing Protection, CSA Certificated, Temp Self Modulating
Color: White
Voltage: 120 Volts (AC)
Maximum Flow Rate: 4.3 Gallons Per Minute
Heat Output: 100000 BTU per Hour per Foot per Degree Fahrenheit
Efficiency: UEF > 0.81
Mounting Type: Wall
Is Electric: No
Manufacturer: Mizudo
Item Weight: 26.1 pounds
Item model number: FDG-CS100W-NG
Special Features: 2 Years Support for Whole Unit, 5 Years Support for Heat Exchanger, Automatic Anti-Freezing Protection, CSA Certificated, Temp Self Modulating
Included Components: Tankless Water Heater, User's Manual, Quick Installation Poster, Assembly Kit, Warranty Card
Batteries Included?: Yes
Batteries Required?: No
Date First Available: October 31, 2024
Frequently asked questions
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This item is non-returnable:
Non-returnable. Transportation of this item is subject to hazardous materials regulation
View our full returns policy here.
Non-returnable. Transportation of this item is subject to hazardous materials regulation
View our full returns policy here.
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Top Amazon Reviews
Material Type: 3.6 GPM, 80,000 BTU, Indoor
Style: Propane Gas
I installed this hot water heater on a 400sq foot cabin where the old hot water heater had died. Local hot water heaters at Lowes cost over $1000 minimum for identical specifications due to lack of availability on big island. This heater arrived and was identical in size, appearance, and function to the previous heater, except it's digital now, so hookup was quite simple. The led displays are fairly bright, and it's simple to select the desired temperature. This hot water heater is able to sustain extremely hot water fairly indefinitely to a single shower, which was my target. The water flow is good at that volume, and it's operation is fairly silent. Overall quality of the unit seems fine, though time will tell. All in all, I would definitely buy this heater again for a small application like this.
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Reviewed in the United States on December 5, 2024 by Critical Insights
Material Type: 3.6 GPM, 80,000 BTU, Indoor
Style: Propane Gas
UPDATE: I have abused this machine for almost a month now running it at max temperature taking 2 10 minute showers each day between me and my partner. It is extremely efficient, we use small 5 gal propane tanks that and they last roughly 2-3 weeks of us using them a lot. We also hand wash our dishes and it still manages to last super long. This is one of the few indoor built instant propane water heaters on this app and website. It does not disappoint, the price tag reflects the quality. It gives instant hot water and works amazingly as advertised. I've been using this for showers over the past week and it works great. It is super easy to mount and although it doesn't come with the fittings and proper connections for gas or water you can easily find these at your local hardware store. It will cost a little extra but I guarantee after you try it you will love it. I have this unit mounted in my camper that I live inside all year around and it is the greatest upgrade I've done to this place.
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Reviewed in the United States on March 29, 2024 by Ian Z.
Material Type: 3.6 GPM, 80,000 BTU, Indoor
Style: Propane Gas
Awesome water heater, it heats up fast and gives hot water for a long time. I had an issue that their customer service fixed courteously and fast. This unit is perfect for my one bedroom tiny house. Works great, Thanks
Reviewed in the United States on September 2, 2025 by C
Material Type: 3.6 GPM, 80,000 BTU, Indoor
Style: Propane Gas
I paid more for this product than many of its competitors with the thought that you get what you pay for. I installed it in late spring of 2024 and it worked great through the winter. This is heating a tiny house and serves one shower, and one sink, neither are used at the same time. Winter hit and it started shutting down on me and after some research, I discovered that the propane tank needed to be kept warmer. Keep in mind I live in the desert of New Mexico. Once I built a heated compartment around the propane tank, I was sure that would fix the problem. WRONG! Now it gives a different error code and will produce 60-90 seconds of hot water before turning cold. Then you turn the water off and immediately back on, wait for it to heat up again and get another 60-90 seconds of hot water. After going through this mess of a cycle 3 to 4 times, you can actually get several minutes of hot water, up to about 5 and a half minutes before it gets cold again. According to the error code it could be one of 3 different problems, none of which make any sense. I bought this because I needed a DIY unit with no plumber fees. What I got was a mess. Shower time should be relaxing but my showers are now the worst part of my day…. Don’t buy this unless you don’t mind a product that is not dependable and doesn’t work as they said it would…. UPDATE 2-11-2025 After posting the above review, the company reached out with a misleading email which stated that they were offering me a full refund for my trouble. I wasn’t looking for that, I just wanted to post my experience with this product. When I responded to their message, they offered me customer support instead of a refund which I was very happy about. I need a working water heater, not my money back. I utilized the help from customer support and though the problem got better, It was still persistent. So I let them know this, hoping for more fix options. Instead they ask for my elevation which I gave to them. Now they have come back with a screen shot of their Q&A stating that the unit is not recommended for use above 2000 ft above sea level. I’m in the desert at 3600. Their offer now is to send me a shipping label and return the unit. I get that chemical reactions like cakes rising and things like that are affected by altitude but I worked 8 years a s a plumber and never once did we instal a water heater that had an elevation requirement on it. This is nonsense and completely unacceptable. I don’t know anyone who would ask about an elevation requirement on a water heater and more than that don’t understand why they would make a unit that can’t work at all elevations… don’t waste your time or money, there are far better products out there.
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Reviewed in the United States on February 3, 2025 by Daniel
Material Type: 3.6 GPM, 80,000 BTU, Indoor
Style: Propane Gas
We’ve used on-demand gas water heaters for years and watched the technology evolve with considerable progress. Twenty years ago, a top of the line tankless heater (in the US) cost >$2000 and required much higher propane or gas pressures and flow rates and much larger venting systems. Fast forward to the present. With all vents, flashing, pipes, and other hardware, this unit cost me <$500 to install and does cartwheels around the older models I’ve installed and used before. So simple, a non-plumber could easily do it. Easy to install, easy to operate, good safety profile, great price. Love it.
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Reviewed in the United States on July 16, 2025 by James Li
Material Type: 3.6 GPM, 80,000 BTU, Indoor
Style: Propane Gas
We just opened this yesterday to see what parts would be needed for the installation. Everything was very well packaged, but I noticed that when we opened the plastic bag, the unit was in was wet! It looks like someone else used it and then decided to return it. I paid for a new unit!! Unfortunately, my husband insisted on going ahead with installing it on Sunday instead of sending it back!! If all goes well tomorrow, I will reevaluate my review. Why was it wet??? I truly am upset since this is an early Christmas present for my son and his family! UPDATE: Oct12, 2023- It works great! So far no problems. Though if you run the water too fast it turns cold! Guess you don't need high pressure when filling tub, but a nice shower has lots of hot water with pressure...unfortunately, this is just OK for showers.
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Reviewed in the United States on June 24, 2023 by Deb
Material Type: 3.6 GPM, 80,000 BTU, Indoor
Style: Propane Gas
Easy to install, and with a couple of fittings propane hooked up in no time. Very easy to adjust the temperature too. And it works with my 12-v water pump.
Reviewed in the United States on July 6, 2025 by pia cummins
Material Type: 3.6 GPM, 80,000 BTU, Indoor
Style: Propane Gas
easy to install, works great
Reviewed in the United States on July 15, 2025 by Amazon Customer