Takagi AT-KJr3U-OS - User Manual

Questions and Answers:

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nkingAug 13, 2025
Why does my Takagi AT-KJr3U-OS not ignite when water runs through it?
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  John WolfAug 14, 2025
  If your Takagi Water Heater doesn't ignite when water flows through it, ensure the flow rate is over 0.5 GPM. Check the filter on the cold water inlet for any blockages. Inspect for reverse or cross connections. If you're using a remote controller, ensure it's powered on. Verify that the inlet water temperature isn't too close to the set temperature. Confirm the gas supply is turned on and that the unit has power, with the power button on either the controller or inside the water heater activated.
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Elizabeth GilbertAug 17, 2025
Why is my Takagi AT-KJr3U-OS water not hot enough?
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  Shawn WelchAug 18, 2025
  If your Takagi Water Heater isn't producing hot enough water, several factors could be the cause. Begin by comparing the flow and temperature using the charts. Check for cross plumbing between cold and hot water lines. Ensure the gas supply valve is fully open and the gas line is properly sized, with the supply pressure within specified limits. Verify that the set temperature isn't too low and that the Easy Link or Multi-Unit system is correctly configured.
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Bryan SuttonAug 21, 2025
What to do if hot water is not available from my Takagi Water Heater?
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  David WillisAug 21, 2025
  If you're not getting hot water from your Takagi Water Heater when you open a fixture, check the following: ensure the unit has a 120 VAC, 60 Hz power supply and that the power button on the controller or inside the water heater is turned on. Also, verify that both the gas and water supply valves are fully open, and the filter on the cold water inlet is clean. Make sure the hot water fixture is sufficiently open to draw at least 0.5 GPM through the water heater, and check that the unit is not frozen. Finally, inspect for cross plumbing between the hot and cold water lines, and ensure the Easy Link or Multi-Unit system is set up correctly.
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wmurrayAug 25, 2025
How to get hot water faster from my Takagi AT-KJr3U-OS?
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  Jennifer DickersonAug 26, 2025
  The time it takes for hot water to reach your fixtures from your Takagi Water Heater depends on the length of piping and the pipe size between the two. The longer the distance or the bigger the pipes, the longer it will take to get hot water. If you want hot water more quickly, consider a hot water recirculation system.
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Jessica GoodwinAug 28, 2025
Why is the hot water temperature fluctuating with my Takagi AT-KJr3U-OS Water Heater?
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  Tonya MccannAug 28, 2025
  If you are experiencing temperature fluctuations with your Takagi Water Heater, ensure the filter on the cold water inlet is clean. Check that the gas line is properly sized and the supply gas pressure is within specified limits. Also, check for any cross connection between the cold and hot water lines, and verify that the Easy Link or Multi-Unit system is set up correctly.
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Robert EvansSep 1, 2025
What to do if my Takagi AT-KJr3U-OS's hot water turns cold and stays cold?
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  Mackenzie GarciaSep 1, 2025
  If the hot water from your Takagi Water Heater turns cold and stays cold, first check if the flow rate is enough to keep the water heater running. If you have a recirculation system installed, ensure the recirculation line has enough check valves. Also, verify that the gas supply valve is fully open and the filter on the cold water inlet is clean. Lastly, ensure that your fixtures are clean of debris and obstructions.
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Brandon ThomasSep 5, 2025
Why is the display not working on my Takagi AT-KJr3U-OS controller?
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  Bradley GreenSep 5, 2025
  If the built-in or remote controller of your Takagi Water Heater doesn't display anything when turned on, first ensure the unit is receiving power. For the remote controller, check that the connection to the unit is correct. Note that when the built-in controller is turned on, the STAND BY LED should be lit. Also, if the unit hasn't been used for five minutes or more, the display might turn off to save energy. Finally, in an Easy-Link System, only the parent unit's controller will display the set temperature.
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Michele DanielSep 8, 2025
Why does the fan motor keep spinning on my Takagi AT-KJr3U-OS after it stops?
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  hwilsonSep 9, 2025
  It is normal for the fan motor of your Takagi Water Heater to continue running for 15 to 70 seconds after operation has stopped. This allows for quick re-ignition and purges exhaust gas from the flue.

Takagi AT-KJr3U-OS Specifications

General

Type	Tankless
Fuel Type	Natural Gas
Flow Rate	6.6 GPM
Weight	38 lbs
Maximum BTU Input	140, 000 BTU/h
Efficiency	82%
Maximum BTU	140, 000 BTU
Energy Efficiency	82%
Input (BTU/h)	140, 000
Venting	Direct Vent