Takagi T-KJr2 Tankless Water Heaters Review

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Takagi T-KJr2 series is the most popular series from all Takagi tankless water heaters. Compare the old T-KJr model with the new T-KJr2 IN/OS models and see the review of the top features. 

Original model T-KJr was released in 2003 as the smallest unit among Takagi water heaters. In 2010 two new T-KJr2 models have been offered, which are known as T-KJr2-IN, an indoor, and Takagi T-KJr2-OS, as the outdoor model. Both are non-condensing models.

All T-KJr2 models are designed for domestic hot water heating, on-demand and in endless supply, and recommended for smaller homes, apartments, condos, cottages, and households with up to two bathrooms or fixtures.

Takagi TKjrThe small and compact size of approximately 14"x22"x8" and capability for the wall installation, allows Takagi T-KJr2 models to save on the floor space, which would be usually occupied by the tank type heater

These models are not heating water only but can be used with storage tanks, recirculation systems and work with the radiant floor and baseboard systems for space heating.



Takagi T-KJr2-IN is an indoor model that can be converted to a direct vent unit with the sealed combustion, and installation in rooms with the limited amount of fresh air (confined spaces). With the direct vent conversion kit, T-KJr2 can be installed in mobile and manufactured homes too.

The venting system on T-KJr2-IN utilize the 4" stainless steel pipe and based on the installation options it can be terminated horizontally or vertically. The intake pipe can use smaller and cheaper PVC pipe.

T-KJr2-OS is an outdoor model (it cannot be installed indoor) and it does not require venting.


The gas burner has potential to provide approximately 140,000 BTU, which can produce the maximum of 6.6 GPM of hot water, which is sufficient for one to two fixtures operating simultaneously.

Remote control

The remote controller is the standard feature and it allows you to set one of 16 temperature settings, between 99 F and 167 F.

Another advantage of having the remote controller is an easy troubleshooting. Thanks to the electronic circuit board, T-KJr2 water heaters are self-diagnostic, so if anything goes wrong with the unit, the diagnostic error codes, such as 03, 11, 70, 71... will display.

Modulating gas and water valve

The water heater works in the range from its minimum of 19,500 BTU to its maximum power of 140,000 BTU, thanks to the fully modulating burner. The electric circuit board adjusts, based on the inputs, the power on the burner and water valves, while monitoring the incoming and outgoing temperature. This way, you are getting the right amount of hot water at the right temperature, with less fluctuation and reduced energy consumption. As opposed to more advanced non-condensing units, this product cannot be combined in the multi-link system.


To start the heating process, the water heater does not use the old pilot light ignition but the advanced electronic ignition system that automatically lights the burner.

Safety features

  • Built-in freeze protection sensor

  • Hi-limit switch

  • Flame sensor

  • Overheat protection

  • Flue backdraft pressure switch

  • Thermistors for constant temperature monitoring

  • Combustible air sensor will shut the unit off if there is not enough combustible air supply


  • Gas input is from 19,500 to 140,000 BTU for natural gas

  • Gas and water connections - 3/4"

  • Water pressure: 15 psi to 150 psi

  • Weight from 28 to 35 pounds

  • Recirculation pump can be used

  • Water flow: min. 0.75 to max. 6.6 GPM

  • Energy factor for natural gas is 0.82

Small size and capability to heat potable water efficiently, combined with the space heating, is what makes Takagi T-KJr2 models a good buy.

Takagi T-KJr2 are also available as the Ultra-Low NOx models - T-KJr2U, which complies with the strict regulations that deal with the pollution and emission of the products of combustion.

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Pictures are courtesy of Takagi WH company

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