Takagi Tankless Water Heater Reviews (2024)

After central heating and cooling, water heating is the second highest energy end use in American homes. It accounts for 25% of domestic energy usage, and it costs homeowners between $200 and $600 per year. As such, it’s necessary for homeowners to consider energy efficiency when purchasing their next water heating system. 

If you’re in the market for a reliable, affordable, and energy-efficient water heater, then a Takagi tankless water heater is your best choice. Investing in a Takagi tankless water heater is one of the smartest and most cost-effective solutions to ensure a steady supply of hot water in your home.

I’ve reviewed the most efficient Takagi tankless water heaters using a painstaking six-step process to help you make the best choice for your home. I’ve listed them in order of energy efficiency.

But first, let’s find out more about the company.

The History of Takagi

Takagi has its origins in Japan. It was established in 1946 as Takagi Machinery Co. and became a limited company six years later.

Takagi established its present headquarters in Fuji-city, Shizuoka Prefecture, Japan, in 1956 and began manufacturing gas and kitchen appliances, including its first collection of single-burner and double-burner tabletop gas stoves.

In 1962, Takagi had a prosperous year after the release of the first auto-igniting hot water heater. In 1980, it was the first company to create a water heater with proportional control gas valves that could remotely reheat water. In 1990, Takagi created the first water heater with a temperature control module and a commercial multisystem.

Twenty years later, on Wednesday, June 16, 2010, Takagi established a joint venture with American manufacturer A.O. Smith to market and manufacture tankless water heaters in North America. Through the joint venture, A.O. Smith will offer a full line of tankless gas water heaters under its own brands in association with the Takagi brand and will assume responsibility for the Takagi brand in the US and Canada.

Takagi Tankless Water Heater Reviews

Takagi has a huge variety of propane and natural gas tankless water heaters. In fact, its product line consists of over 10 distinct model series to choose from. After a long, arduous, and resource-consuming review process, I was able to whittle down the list to the three best Takagi tankless water heaters. These models include both condensing and non-condensing units. 

Here they are in order of power and efficiency:

1. Takagi T-M50 series of non-condensing tankless water heaters

The Takagi T-M50 series of tankless water heaters was developed primarily for heavy-duty applications. It has the largest capacity in the company’s line-up, and it also generates one of the highest GPM (gallons per minute) in the industry. The T-M50 series is ideal for residential and commercial applications that require the most robust and high-demand tankless water heaters.

Despite not being a condensing unit, this hyper-efficient water heater is not only intended to give an unlimited supply of hot water but also to guarantee superior safety and dependability. It is one of the most powerful tankless water heaters available, with a maximum flow rate of up to 14.5 GPM.

These Takagi water heaters are built with low nitrogen oxide (NOx) emissions to lessen the environmental effects brought about by greenhouse gasses. It also contains an internal freeze protection system that guarantees the heater continues to function even in sub-freezing temperatures and maintains a safe and efficient water temperature.

An additional safety feature of this heavy-duty T-M50 tankless water heater is an overheat cutoff fuse that ensures the combustion chamber is not affected in case of any breaches. This indoor/outdoor natural gas water heater has input and outlet thermostats for continuous temperature monitoring.

There are four distinct models in this series:

• T-M50-N (natural gas)
• T-M50-P (liquid propane)
• T-M50-ASME-N (natural gas)
• T-M50-ASME-P (liquid propane)

These models are available in both indoor and outdoor models. Since there are no storage tanks to fill, you can have as much hot water as you want. Depending on the model, these Takagi tankless water heaters deliver close to 500 gallons of hot water per hour, on demand.

The table below shows the T-M50 series’ gas consumption input, thermal efficiency, and maximum flow rate:

All T-M50 Takagi tankless water heaters share the following features:

• They have a low NOx gas burner with a minimum capacity of 15,000 Btu/hour and a maximum capacity of 380,000 Btu per hour, enough to provide a flow rate of 14.5 GPM at a 30°F temperature rise and 6.1 GPM at a 100°F temperature rise.
• Unlike other tankless water heaters that have one primary heat exchanger, these Takagi tankless water heaters are available with a dual heat exchanger design that provides redundancy for added reliability.
• The T-M50 series provides hot water to residential systems (directly or indirectly), which can be used with storage tanks, recirculation systems, hydronic heating systems, and radiant heating applications.
• The heat exchangers are built with a commercial-grade copper alloy called HRS35, a heat-resistant alloy with additive elements that make it much stronger and harder than the standard C1220 copper used in most other heat exchangers. The tensile strength of HRS35 is eight times that of regular copper. HRS35 maintains its high strength and fine grain even when heated to extreme temperatures.
• In warmer climates, where the incoming water temperature is around 70°F, a T-M50 Takagi water heater can deliver hot water to up to seven showers (assuming the heaters are set at 120°F). In colder climates, it can provide enough hot water for five showers simultaneously.
• Takagi water heaters have an air fuel ratio rod, a sensor that ensures optimal combustion at all times. This technology works in tandem with the onboard computer to maintain an optimal air-to-fuel ratio, thereby reducing pollutants and increasing efficiency.
• Other built-in computerized safety features include an internal freeze protection system, which protects the heat exchanger from freeze damage, an overheat cutoff fuse, which ensures that there are no breaches in the heat exchanger drum, and a high-limit switch, which ensures that the water temperature does not exceed safe levels.
• The natural gas models have a high energy efficiency rating of 80%, while the liquid propane units have a thermal efficiency rating of 82%.
• T-M50 heat exchanger tubing is 25% thicker to ensure durability. The heat exchanger is put under less heat stress when the drum is thicker.
• Takagi has a proprietary Easy-Link system that allows you to cascade 4 units, and with the addition of a multi-unit controller, you can connect up to 20 Takagi water heaters.
• Optional accessories available with these Takagi models include a temperature remote control, a direct vent conversion unit, a pipe cover, a vent cap, and a backflow preventer.

The T-M50 Takagi tankless water heaters are available for purchase for around $3,500 in select retail stores. This figure might seem high for most people, but considering that this tankless water heater series is guaranteed to last for 20+ years, you’ll get the return on investment within a few short years. 

However, there are a few issues I came across while reviewing the T-M50 tankless water heaters. The warranty coverage is much lower compared to other tankless water heaters on this list. They only cover the heat exchanger for six years and provide a five-year parts warranty.

After a few years of use, several users have complained that their units experienced gas leaks. Takagi attributes this to the use of the typical Type B vent, which, owing to acidic condensation, may rapidly damage the heat exchanger. Improper venting may result in exhaust gas leaks, which would be dangerous. All Takagi non-condensing tankless water heaters must utilize Category III-approved, hermetically sealed stainless steel vent pipes.

The T-M50 tankless water heaters feature state-of-the-art technology and materials to provide superior energy efficiency, performance, and long service life. If you have a large home or small business with a substantial demand for water, the T-M50 is worth checking out as it provides unbridled performance compared to anything the market has to offer.

2. Takagi residential condensing tankless water heaters with X3 technology 

Have you ever seen a crusty white or green material on the walls of your shower, showerhead, or faucet? That’s lime scale. Also known as scale deposits, lime scale is formed when calcium in water separates and starts to build up.

Although not as obvious, this similar process happens to varying degrees within both storage tanks and tankless water heaters, depending on the hardness of the water in your location.

Takagi created the X3 Scale Prevention Technology by combining its experience in water heating and treatment. This technology increases the life of the unit three times longer than other conventional tankless water heaters by preventing scale from accumulating.

As a result, these are the first tankless heaters on the market to maintain peak performance for longer without the need for scale-related maintenance. Takagi backs this groundbreaking technology with the industry’s first “Peace of Mind” limited warranty. This 15-year limited warranty includes coverage for any scale-related problems that might occur.

There are six units within this model series that are distinguished by their maximum gas consumption input and maximum flow rate. These units include the following:

• TK-540X3-NIH
• TK-540X3-NEH
• TK-340X3-NIH
• TK-340X3-NEH
• TK-240X3-NIH
• TK-240X3-NEH

*For propane fueled models, the “N” in the designation is replaced with a “P” 

These Takagi water heaters are Energy Star qualified, which not only means that they meet the strict energy efficiency criteria set by the US Environmental Protection Agency and Department of Energy, but it also means that users who buy these products are eligible for a federal tax rebate on energy-efficient residential tankless water heaters.

The following table shows the gas consumption input, uniform energy factor rating (UEF), and maximum flow rate of these condensing water heaters:

*For propane models, the minimum Btu/Hr is 13,000

The X3 condensing units have the following salient features:

• Just like the previous T-M50 models, the X3 models also have a dual heat exchanger design. The primary heat exchanger is constructed of commercial-grade copper that is more resilient to corrosion, while the secondary heat exchanger is made of 316L stainless steel to protect against corrosion.
• The X3 anti-scaling technology ensures that annual descaling maintenance is not necessary.
• All X3 condensing models can support a maximum of four simultaneous showers in warm climates and three showers in cold climates. 
• All X3 Takagi water heaters have several safety features, including an overheat cutoff fuse, an air-fuel-ratio rod, and an internal freeze protection system.
• Optional extras also available for purchase include a multi-unit controller that is capable of handling up to 20 units at one time and also works as a diagnostic tool that provides troubleshooting diagnostic codes, a temperature remote control, and a neutralizer kit that connects to the condensation drain.
• These water heaters are available in both outdoor and indoor models.
• Tankless water heaters with X3 Technology may be used with an external recirculation pump and a crossover valve.
• These tankless water heaters are available with a 15-year residential warranty on the heat exchanger, and a 5-year residential warranty on parts. As mentioned earlier, the 15-year warranty also extends to any scale-related issues that may occur. 

Retail prices for the X3 series vary from $1,200 to $1,600 at select retailers. This is a bargain compared to the price of the M-T50 series and if you consider the extensive warranty period, high energy efficiency, and anti-scaling technology, these heaters really do provide more value for your money compared to most brands. 

While reviewing this tankless water heater series, I didn’t encounter a large number of customer complaints. However, a handful of users I talked with complained about temperature fluctuation issues with the units they purchased.

In response to my inquiry, Takagi advised them to check for “cross flow” in the plumbing, which indicates there’s a connection somewhere between hot and cold water supply.

This may be as unassuming as a single-handle faucet with a damaged seal. To test this, turn off the cold water supply to the heater and either open the pressure relief valve or any hot-water faucet. If water continues to flow from the fixture after the pipe has been emptied, there is a cross flow in the plumbing that must be repaired. This is a plumbing issue that a certified plumbing contractor can fix really quickly.

The X3 tankless water heater series are some of the most highly efficient and highly durable residential heating solutions on the market. They can provide hot water to up to four showers simultaneously and no yearly maintenance is needed! 

Check out the website for more information.

3. Takagi H3 residential condensing tankless water heaters

If you live in a town apartment, condominium, or smaller household where the hot water demand is not as high, the Takagi H3 tankless water series has models that can provide enough hot water to up to three fixtures simultaneously. These include the following:

• T-H3J-DV-N (indoor model)
• T-H3J-OS-N (outdoor model) 
• T-H3M-OS-N (outdoor model)
• T-H3M-DV-N (indoor model)

*For propane fueled models, the “N” in the designation is replaced with a “P” 

These units are perfect for any homeowner who needs uninterrupted hot water supply to up to two showers and a kitchen faucet. The table below shows the maximum gas input, energy factor, and water flow rate capacity of these H3 tankless units:

Other important features include the following:

• These Takagi tankless water heater series can be used for both residential and commercial applications. Using Easy-Link, you can connect a maximum of 4 additional water heaters and if you opt for the optional Multi-Link controller, you can connect up to 20 units.
• They include computerized safety features, such as an air fuel ratio sensor, an exhaust and water temperature safety control system, and an overheat cutoff switch.
• All H3 models are Energy Star qualified, which means users are eligible for federal tax rebates on residential energy-efficient heating systems.
• Accessories available with every purchase include a neutralizer kit, a pipe cover, isolation valve kits, and a remote temperature controller.
• This tankless water heater series has a double heat exchanger design. The primary heat exchanger is constructed of highly durable commercial-grade copper while the secondary heat exchanger is made of type 316L stainless steel to protect against corrosion.
• Since they are direct vent units, they provide for flexible venting with PVC, CPVC, or ABS pipes for intake and exhaust (solid core only).
• These units are available with a 15-year residential warranty on the heat exchanger (5 years in commercial applications), and a 5-year limited warranty on parts.

The H3 tankless water heater series is available for purchase for a price range of between $800 and $1,200. These are some of the most affordable units in the market. The only problems that some customers have with this unit is the water not getting hot enough. As I mentioned earlier, this can be an installation issue where there is a crossflow connection that disrupts the flow of hot water. Takagi advises its customers to seek the help of a licensed plumber when installing its units, otherwise they risk voiding the warranty.

The Takagi H3 series of condensing tankless water heaters is well suited for residential/ commercial applications, such as small restaurants and beauty salons. Like other high-efficiency natural gas tankless water heaters, this direct vent unit has a condensate discharge port to which you need to attach a 1/2″ PVC line. To learn more about this tankless water heater series, visit the website today.

The Bottom Line

Takagi is one of the top manufacturers of on-demand gas tankless water systems in the world. They have almost 60 years of experience in producing hot water systems.

In contrast to antiquated, wasteful electric storage systems, Takagi on-demand hot water systems only heat water when it’s needed. There is no inefficient heat loss because there is no storage tank that constantly recirculates hot water. They produce 25%–33% fewer greenhouse gas emissions than other gas water heaters, making them more environmentally friendly.

Takagi is renowned for its groundbreaking inventions and developments in on-demand hot water heaters. They designed the first completely computerized controlled tankless gas water heater, a breakthrough automated gas control valve system, and a safety system for its tankless hot water heaters, among many other significant achievements.

Takagi provides natural gas tankless water heaters that are dependable, robust, cost-effective, and highly efficient to meet your hot water demands.

Takagi Tankless Water Heaters Review Methodology

This section describes the steps I used to evaluate the best Takagi tankless water heaters.

Step 1: A list of all Takagi water heaters

I began my investigation by compiling a list of the Takagi tankless water heaters with the highest distribution rates in the United States. It took hours of research on websites such as Amazon, Home Depot, and Target to determine the most popular Takagi tankless water heaters among US consumers.

Step 2: Online reviews

For this step, I analyzed consumer feedback on key review sites, such as the Better Business Bureau, TrustPilot, Google Business, and Amazon Reviews. It was essential that I gather customer feedback to establish whether the manufacturer’s claims were supported by customers.

Step 3: Product analysis

Third, I made a wish list of essential features for my ideal tankless water heater. To be fair, I also looked at how the Takagi water heaters fared in comparison to electric tankless water heaters and other forms of storage tanks. My requirements and the questions I needed answered are outlined below:

• What makes a tankless water heater better than a conventional storage water heater?
• What are the advantages of a gas tankless water heater over an electric tankless unit?
• How does a Takagi natural gas model stack up against what other brands have to offer?
• What safety features are incorporated into a Takagi tankless water heater?
• What proper ventilation techniques are required during installation?
• How much hot water does each Takagi water heater series supply during peak use periods?
• How does the Takagi product warranty compare to that of other brands?
• Does Takagi provide both indoor units and outdoor units in every model series?
• Are Takagi water heaters competitively priced?

Step 4: Interviews with real customers

Next, I spoke with actual users who had firsthand knowledge of the Takagi brand. So, I called a few buddies and organized a door-to-door survey within a 30-mile radius of my location. I also talked with a few plumbers about their experiences with Takagi water heaters, specifically the problems they’ve come across while installing these units. I also conducted an online poll on Facebook and Twitter to increase my reach. After five days of intensive legwork, I had collected adequate information to start my review.

Step 5: Getting in touch with Takagi

Next, I contacted Takagi to get a reaction to the unfavorable customer reviews I had seen on internet review sites. This enabled me to examine how staff interacted with customers and how they responded to extreme pressure.

Step 6: Test drives

I then requested Takagi send over a few of its tankless water heaters for a detailed evaluation. I was uncertain about the outcome, but figured it was worth a shot. Surprisingly, I got a prompt answer, and Takagi promptly sent all of its tankless devices along with a service team. Therefore, I rented a warehouse, hired two water bowsers, and began rigorously testing each water heater.

Final Thoughts

A Takagi tankless water heater is one of the most cost-effective and energy efficient hot water systems to purchase, install, and run. Because hot water accounts for around 25% of home energy use, improvements in the efficiency of your hot water system flow directly impacts your overall gas bill.

The market for tankless water heaters is particularly difficult since there is seldom a single best heater. As for me, I tend to be quite fanatical about versatility. This is why I rank the Takagi H3 model series as my number one choice.

It does everything, including light commercial applications (which very, very few tankless water heaters from any brand can boast of). It’s affordable, it’s suitable for any form of residential or commercial building in any climate, and it’s also fitted with a host of safety features and has one of the best warranty coverages in the industry.

If you need a water heater that is durable, efficient, and has great warranty coverage, Takagi has a model that will suit your needs. Check one out today.

Also, if you want to find out what the competition has to offer, check out my review of the seven best tankless water heaters for your home.

Furthermore, if you’re seeking reviews on water heaters from different brands, our comprehensive collection of water heater reviews offers an extensive range of options available on the market. These reviews are designed to provide detailed information and valuable insights that will assist you in making an informed decision.

Whether you’re considering specific brands or exploring a variety of options, our reviews can help you gather the necessary information to choose the right water heater for your needs.

• Navien Water Heater Reviews
• Rinnai Tankless Water Heater Reviews
• Eemax Tankless Water Heater Reviews
• Paloma Tankless Water Heater Reviews
• Stiebel Eltron Tankless Water Heater Reviews
• Ecosmart Tankless Water Heater Reviews