Takagi T-KRj Burner does not fire

Please reach out to your local plumber.

Most on demand or tank-less units require a minimum flow rate before the unit will fire up, they designed them that way so small water leaks (drips etc.,) keeps the unit from going on needless;y. Try opening the shower hot water fully and see if it comes on, If it does, try closing it slowly to see where it shuts off. Make sure your shower head is clean and not blocked with calcium, which will restrict the water flow. You could also try changing the shower head to one that allows more gallons per hour flow rate. Also make sure the cold inlet and hot outlet valves on the unit are fully open and the diverter on the shower is fully open as well.

on start up the clicking noise is normal as well as knocking noise ....one important item with fan , if the fan was removed cleaned and then reinstalled with power to unit could have ruined the fan and it will have to be replaced..... Cant tell you why is wasn't firing before with no codes...other than flow sensor not working( most likey stopped with sand fragments or trash) the flow sensor detects hot water demand and ignites heater and if clogged it will not light up but doesn't give error code and the water running through hot side will be cold..... flow sensor is a turbine that detects water movement and lets heater light..... may want to get serviceman to check this out and clean turbine.... hope this helps...

There are several things I would look for:
-Flashing burner light (indicates an error code)
-Trying flowing more hot water. In the summer alot of times you'll flow less hot water because your cold water is warmer. If you flow additional hot water at your shower, it will ensure the unit stays firing
-If the unit doesn't fire at all, you may have debris in your cold water filter or a stuck flow sensor. Call tech support to help you with cleaning a flow sensor.

If you are the technical type you can take it apart and clean the burner, the thermocouple and the chamber....This may fix it. If it is the orface that needs to be cleaned, call the gas company, they will clean it for you for a small fee.
good luck,
James.
----PLEASE CLICK ON 4 THUMBS UP 4 ME----

Yes the faucet could be a problem. Try changing for one which you know is ok.
The long run of pipework - each bend, elbow or joint all have a reducing effect on the flow, maybe enough to matter with a restricted outlet. none of this can be altered except by renewing with larger bore pipe - expensive!
Also there should be a dirt filter in the mains water input line/pipe. Try removing & cleaning. Try also removing , reconnecting and then the hot tap [faucet]

The boiler will have an actuator valve which fires it up when a certain flow of water is reached. If the flow is reduced AND the valve is worn, maybe a replacement. Not sure about it's USA construction but in the UK [it's called a diverter valve] many have a rubber diaphragm which is cheap to replace
Check also if it uses a flow sensor switch
Had a look at the Takagi web site and there are pdf's of manuals
takagi.com
Overall I am still thinking that the main prob is in the flow.
Hope I've helped - come back anytime
Rod.Davies

You're most likely getting a pressure wave (spike) that is generating momentary flow across the flow sensor. The heater is registering this "instant" flow and beginning its firing sequence. Once the flow dissipates, the unit then goes into a purge cycle. I'd recommend having your water pressure tested to make sure it isn't abnormally high (above 60 psi) or abnormally low (below 30 psi). Assuming the pressure is normal, you can use a pressure reducing valve or pressure regulator to absorb the spikes and stop the unit from cycling.

It's your water flow sensor! The gray thing inside the unit connected to the chrome inlet line. Take it apart and clean it so the propeller spins again. I had the same problem and cleaned the sensor and it works great! Good luck.

I have the same problem with a T-K3. The Takagi support site recommended cleaning the burner. When the plummer arrived to attempt the cleaning, he was not convinced that it would help. He called the Takagi 800 number and let them hear the problem over the phone. They had him set the fan speed dip switch (#4 on the upper left bank of switches) to the up ("on") position and reset the system. Problem resolved! Why they didn't recommend this when I contacted them, I haven't got a clue. Anyway, the system hasn't vibrated in several days of use.

THE WATER IS RECIRCULATING IN THE UNIT. MAYBE CAUSED BY THE ACID. TRY INSTALLING A BACK FLOW PREVENTER