Takagi as a company only caters to the Tankless water heaters range. Along with assurance and durability, it is also known for its quality amongst its regular customers. The add-on is that the accessories and venting options are also provided by them which save you from the hassle of looking here and there for your tankless water heater parts.
Choosing is relatively a mundane and a tedious task. But, don’t worry; we have got all of it covered up for you. We will summarize some simple steps laid out by Takagi itself on how to choose the best tankless water heater as per your needs.
One of the main points of consideration is the calculation of the temperature depending upon the input temperature and the desired output temperature. The size you wish to purchase for your household purely depends on this number. Here’s a quick reference.
If you want to avoid fluctuations in the temperature in case of multiple connections, you have to keep in mind the number of gallons of water your heater will be able to pump in a minute. This further also depends upon your desired flow rate. The chart as given by Takagi is as follows- Ima
The last function you’ve gotta watch out for is the source of power. Tankless heaters are powered both by gas and electricity. Both comes with their own set of pros and cons. Gas heaters are more efficient as they heat up faster while the Electric ones saves your fuel.
We would suggest you to consider all the above mentioned factors closely as you want it to be a long-term investment without any latter foes in your decision. As a company, Takagi is a good buy with affordable heaters it has to offer and again not to miss out on its quality.
Here are some of the Best Takagi Tankless Water Heaters-
#1. Takagi T-KJr2-IN-NG 
You might have repeatedly seen this model from Takagi on the top list for a reason. It perfectly fits in the budget for a small household of upto 2 bathrooms and a faucet. Which means upto 4-5 adults can have hot water bath without any prior schedule. Additionally, it is environment friendly and saves those errands you need to run for your annual fuel bills. The smart heater turbines work only when the shower or the faucet is turned on. Apart from all this, the model is compact and sleek which is easy to install.
#2. Takagi T-H3-DV-P
As the name suggests, this unit is highly efficient which can give you around 10 gallons of water per minute. This small little machine is enough to heat water for upto 2 sinks and 3 showers without any fluctuation in the set temperature. Takagi specifically assures low emission of NOx propane heater which makes it upto 93% more efficient in nature. Besides, it has automatic shutoff to avoid over-heating and freezing protection.
#3. Takagi T-H2- DV
A bit pricey as compared to the others in this range, but this is the perfect buy which promises an efficient yet resourceful feature. Being one of its kinds amongst its releases, it comes with PVC fittings which offer continuous flow of water to entire household, bigger ones to be precise. It is very powerful with higher efficiency which one cannot overlook while considering its price. Don’t forget, its environment-friendly.
#4. Takagi T-K4-IN-NG 
This one is a bit more efficient as compared to the ones listed above- upto 80% efficient which is a green signal already. It also has some of the same but super-good features such as freezing protection, automatic switch off mode if not used for 20 minutes, and safety from any kind of power surges. It can run upto 2 showers and a sink or other connection easily in warm and cold climates. The only difference here is that it adapts to the cold temperature conditions and heats up the water much more efficiently in about 15 seconds.
#5. Takagi T-K4-OS-NG
This one is for your outdoor purposes. It is compact and hence can be easily accommodated without any fuss. It has built in breeze protection and DOES NOT require any kind of venting. Also, the thermostat installed in the unit is smart enough to monitor the temperature of the water on regular intervals. It can heat water in large amounts perfect for your outdoor hot water needs.