From Japan to Your Home, a Takagi Tankless Water Heater Won’t Disappoint

If you’re reading this, you are either most likely aware of the value a premium-quality tankless water heater offers or you’re interested in learning more about tankless water heaters. The evolution in water heating technology now enables you to get hot water in no time, from a tankless water heater.

Takagi tankless water heaters, as the name suggests, enable you to enjoy hot water without the need to store it in a tank. 

These easy-to-install and use Takagi tankless water heaters take up minimal space and deliver instant hot water whenever you need it. They may take a little investment upfront, but in the long run you will save on your utility bills as they are highly energy-efficient. Plus, they are durable and long-lasting, so you can rely on them longterm. 

Takagi “The First” in Tankless Water Heating Technology

Takagi has earned its reputation by bringing innovation and value into the category of water heating and has been providing users with hot-water solutions since 1952, throughout the world.

Takagi was actually the first to focus on “tankless-only” products when it entered the North American market. It won the race in delivering the most energy-efficient tankless water heater with a thermal-efficiency rating of 95%. In addition, it was the first to use the air-fuel ratio rod. 

Takagi, by focusing on eco-friendly, high-quality, innovative designs, delivers value and wants to play its part in the alleviation of global warming. 

The Takagi Tankless Water Heaters

With the Takagi tankless water heaters you won’t have to limit your hot water usage; these are on-demand water heaters and would provide you with hot water as much as you want, whenever you want it.

They take up significantly less space than storage tank water heaters and save you a lot of fuel costs down the road, because they only consume energy when needed. To sum up, a Takagi tankless water heater is energy-efficient, takes up less space, and delivers you unlimited hot water on demand.

Takagi Tankless Water Heater Reviews

In order to let you make an informed, and in turn, confident decision, we are going to review the best Takagi tankless water heaters with their positives and negatives. While you can find a lot of information on the internet, it won’t clear the clutter in your mind and land you on a practical purchase.

Let’s dig into the details of Takagi tankless water heaters now. 

If you believe in investing upfront and saving longterm, this Takagi tankless water heater, which is the 2nd Generation for this model, will highly interest you. 

It has a 92% efficiency when running on natural gas and 95% efficiency when on propane gas; propane provides more energy per unit than natural gas. Due to propane capability this unit can satisfy all off-grid living dreams of trading in your traditional storage tank water heaters.

Two heat exchangers work side by side for efficient delivery of hot water; the primary copper heat exchanger heats up the water, while the secondary stainless steel heat exchanger transfers the heat released from the exhaust gases to the incoming groundwater, minimizing the energy loss, utilizing most of the energy, and making it one of the most efficient machines out there. 

Another advantage is that you can install the cheaper PVC venting pipes as the condensation and utilization of excess energy to heat the incoming water brings down the temperature of exhaust gases, alleviating the pressure on the vent. 

Additionally, it uses a power vent, which makes sure the exhaust gases are propelled out effectively. The water heater also equips a built-in flow rate, diagnostic, and temperature display. 

With 130,00 BTU/hour to 199,000 BTU/hour variable gas input, the Takagi tankless water heater offers 9-GPM of flow rate. This makes it suitable and efficient for a large household. Impressively, this tankless water heater has a compact size and would easily fit in a tight spot. 




The Takagi T-H2S-OSLP tankless water heater provides constant hot water whenever you want. It’s ideal for those who can invest some upfront coin for a comfortable and economical future. The heater is highly-efficient with energy; the input gas is 90% utilized for heating the water. 

This is accomplished by two heat exchangers; one heating the incoming water through direct fuel energy whereas the second utilizes the excess heat generated from the exhaust gases, minimizing energy loss. 

Greenhouse gases are continuously playing their part in increasing the temperature of the earth. Takagi is playing its part by making low-emission water heaters like this one. The double heat exchanger design allows the utilization of exhaust gases, which makes you a good environmentalist. 

To ensure high-efficiency and low emissions, Takagi uses an air-fuel ratio sensor. The AFR sensor maintains a proper air-fuel ratio by adjusting the fan speed. You don’t need to worry about the unit overheating either; in a potential overheating event, the overheat cutoff fuse takes care of it, giving you peace of mind and letting you take stress-relieving hot baths without fretting. 

The device adds real value to your bathing experience, however, it’s expensive for obvious reasons; the technology is sophisticated, allowing it to heat the water only when it’s needed. Plus, you get to save a lot of space as it heats the water without a tank. 




If you are looking for a small-space tankless water heater, this one’s for you. This Takagi tankless water heater is ideal for residential application, because of its small and compact size, making it perfect for your home use. It can easily provide hot water for 2 bathrooms at a time. 

One of the most important factors to consider before buying a tankless water heater is its installation cost. You can use PVC pipes for venting, which drops down the installation costs significantly. 

The condensing Takagi tankless water heater utilizes two heat exchangers; one is copper and the other is stainless steel. The secondary stainless steel one converts the energy from the exhaust gases into heat and utilizes that energy to heat up the water, making the most out of the available energy. This makes this heater highly-efficient as the loss is minimum, resulting in an energy factor of 0.93 with liquid propane fuel. 

6.6 GPM is the flow rate when working at 35°F temperature rise. Nitrogen oxide is a greenhouse gas, which plays a part in adding to the temperature of the earth. Heat exchangers emit NOx, however, this heater complies with ultra-low NOx regulations, making it safe for the environment. 

With freeze and overheat protection, it virtually requires no attention being paid to it, and you can enjoy hot baths without fretting about safety. Plus, it has a remote control, making it further convenient to use. 




Tankless water heaters have a major plus as they typically provide you on-demand water with no tank storage. You can get a hot steaming bath anytime you want without fretting about the water running out or temperature falling down. 

This Takagi tankless water heater provides you with a stress-free lifestyle when it comes to thinking about your homes water situation, as it will deliver as much hot water you need whenever the hot water is needed.  

Another impressive feature is its small size; it’s a powerful little machine that doesn’t take much space, so you can easily place it anywhere in the home as long as you can vent to the outdoors. 

If you have the money and would like to minimize energy bills in the future, this Takagi tankless water heater’s 0.95 efficiency-rating will not disappoint you. It utilizes two heat exchangers to minimize the energy losses and exhaust gases and complies with regulations of ultra-low NOx emissions, a major greenhouse gas, which makes it minimize the environmental footprint as well. 

Plus, propane is a more efficient-burning fuel than gasoline, adding to the efficiency of the device. The heater also has a high flow rate; with 8 gallons/minute, you can use 3 bathrooms at a time in a warm climate and 2 bathrooms in a colder climate. 

With condensing technology, this Takagi water heater allows you to use PVC venting, cutting down your installation costs. Plus, with the computerized surge, overheat, and freeze protection, you have an additional peace of mind. 




Takagi tankless water heaters are manufactured to offer long-term service. On top of that, the company offers impressive warranty for their residential tankless water heaters, 15-years on the heat exchanger and five years on all of the other parts, except for fuses, to make you feel at ease while using their devices. 

This Takagi water heater comes with an impressive 15-year limited residential warranty. So, even if something malfunctions in the heat exchanger, you can get it fixed without hassle. 

The self-diagnosis feature Takagi offers is great, however, the technicians may not be highly skilled enough to provide an effective fix to a malfunction, so giving Takagi a call may be needed. 

The Takagi T-H3-DV-N is equipped with an easy-link system, so if you ever want to add up to 3 more water heaters to your homes system, you can do that.

Similarly, the multi-link system allows you to make a whole 20 unit system, but that would be ideal for a commercial setup.  

While the heater is pricey, you can use the relatively cheaper PVC vents to drop the installation costs as the setup won’t need stainless steel vents due to the condensing technology used. 

This Takagi water heater also complies with the NOx emissions regulations, clearing up its name from the list of major environmental pollutants. The double heat exchanger setup helps utilize the heat from the exhaust gases, significantly reducing heat wastage and improving the efficiency of the device for lower gas bills. 

You can get an unlimited supply of hot water with this Takagi tankless water heater, however, the hot water may not be instant if the heater is installed at a distance from your tap. Make sure it’s close so that you don’t have to waste the initial cold-water inlet. 




Takagi Tankless Water Heaters Manual

Each Takagi tankless water heater should come with an installation and operational manual that also has maintenance, troubleshooting, and other necessary information for the user. If your box didn’t have one you can either reach out to the company for them to send you a hardcopy or you can download a manual here

Takagi Tankless Water Heater Warranty

The residential Tagaki water heaters come with a 15-year heat exchanger warranty and a 5-year warranty for other parts, adding to your peace of mind and letting you enjoy the warmth without worry. 

Takagi Tankless Water Heater Troubleshooting

Virtually every service problem can be diagnosed and fixed by external and internal troubleshooting. Takagi tankless water heaters’ troubleshooting guide that comes with every equipment can be used to diagnose and eradicate any problem.

Takagi Tankless Water Heater Maintenance

Maintenance is mainly necessary because of the calcium and magnesium buildup inside the unit. While you can also install a water softener, it’s pretty convenient to descale or flush the system using just vinegar and a small pump. The process will be discussed below. 

Takagi Tankless Water Heaters FAQs

1. How to Clean Takagi Tankless Water Heater?

Cleaning your Takagi tankless water heaters is simple. First of all, you need to make sure you have the right valves. Your heater’s cold and hot side adapter should have isolation valves so that water can enter and exit from the heater only, cleaning up the insides. 

You would need a small pump to propel the cleaning liquid through the system. Get a bucket and put a couple of gallons of white vinegar in it. Turn off the heater and the valves connecting the heater to the water supply and house taps. Attach a garden hose to the isolation valves at both the hot and cold sides of the heater. Place the cold-side hose into the bucket for drain and start pumping the vinegar through the system from the hot-water side valve. 

Let the cycle run for an hour and reverse the process; attach the pump with the hot side and drain at the cold side. 

2. How to Install a Takagi Tankless Water Heater?

While it’s recommended that you contact a professional technician to get it installed, a Takagi tankless water heater is pretty easy to install by yourself as well. You just need to keep in mind certain things before and while installing it. 

Find out if you are getting hard water in your water supply; if it is hard water, you may need to install a water softener. 

First of all, locate a spot where you want to install the heater. Install the PVC or stainless steel vent into the ceiling. 

Give the heater a gas connection, a cold and hot water connection, and a power connection. Electricity is used for controls that operate the appliance, for instance, fans and fuse. 

Install an isolation valve on the cold water inlet and hot water outlet for any future maintenance. You can use the manual given by Takagi to get a deeper insight into the whole process. 

3. How to Descale a Takagi Tankless Water Heater?

It’s recommended that you install a water softener if your water supply contains hard water. Hard water can end up building scale in the copper heat exchanger, reducing its lifespan. Alternatively, you can descale a Takagi tankless water heater once every 12-months to ensure proper working and longterm application. 

Use any descaling chemical to flush out the scale from the insides of the water heater by using the process discussed above for the cleaning of the unit. Make sure to flush out the chemical after descaling by circulating clean water a couple of times. 

4. How to Flush a Takagi Tankless Water Heater?

Turn the Takagi water heater off, close the cold water valve, and let the water inside of the appliance cool for a while. Attach a garden hose or drain to the drain valve and open a couple of faucets to prevent vacuum formation inside the unit. 

Open the drain valve, the water inside will drain out with taking out contaminants with it. You may also use the technique discussed for descaling to flush the Takagi tankless water heaters more effectively.