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Anonymous Posted on Apr 22, 2012

991 error code on a Takagi T-K3 Flash gas tankless water heater

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  • Contributor 1 Answer
  • Posted on Dec 24, 2012
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Re- set code!!!!
We have a Takagi TH3 DV 540 model.Air intake got blocked with snow, condensation etc.Once we cleared that then you just have to re-set it to clear the 991. On our model there are 4 tiny buttons across the bottom (Take off front cover) to find them. of the computer board assembly bottom left corner. Push the two buttons on the right simultaneously hold for 15-20 seconds or so, then turn the Takagi off then on again- should work now!
If you have a different model then those buttons will be in the bottom left corner still but running vertically- try doing as above with the bottom two buttons. We had to go without heat and hot water for 2 days until we could get hold of someone to tell us this. We called Seneca Supply 716-852-4744. Good luck

  • Tim Strepek
    Tim Strepek Jan 15, 2015

    This worked perfectly... as my plumber sat and read them manual, i found this solution, showed him, we did it and it totally fixed the problem! Thanks for posting!

  • Kirk Maes
    Kirk Maes Jan 02, 2018

    Super helpful. I could not find this solution in the installation or Service manual. Could be really frustrating if you perform other fixes but don't know about this final step.

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4 Related Answers

Anonymous

  • 43501 Answers
  • Posted on Mar 05, 2011

SOURCE: turn on power,15-20 seconds later,get

Hi,
First things... you have checked the inler filter andthe gas pressure, but have you checked and cleaned the thermistor(s)??? Also the flame sensor... clean that with a soft cloth...
Next turn down the temp with th dip switches that should tell you if it is the high limit...
Has the unit been cleaned with vinegar or CLR lately or ever??? there maybe buildup internally in the unit...
Is the flame a nice blue color or is it yellow???
Does it go out just before the unit cuts out???
Do the flames lift from the burner???

These are all things that I would be checking if I was coming to your home to check this unit...

Comment back with any other questions or comments...

heatman101

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Rod Davies

  • 150 Answers
  • Posted on Feb 22, 2010

SOURCE: Tankless water heater not meeting the need

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

Anonymous

  • 250 Answers
  • Posted on Oct 24, 2009

SOURCE: tankless on demand water heater.

Tankless water heaters normally take a little longer than a regular heater to provide hot water because they have to start and get warmed up. I'm guessing the heater uses a pilot light and that the short amount of hot water when you turn on the tap is hot because when the water is sitting still in the heater the heat from the pilot light is enough to get it hot. The tub faucet will get hot a lot faster than the shower because it lets a lot more water through and empties out the pipes faster than the shower. You could probably speed things up by letting the tub faucet run on completely hot for like 10-15 seconds and then turning on the shower.

Anonymous

  • 43501 Answers
  • Posted on Mar 26, 2011

SOURCE: Hello, i have a Takagi

Hi,

Not sure if you have the manual for that so here it is.....

http://www.takagi.com/download/product_manuals/T-M1.pdf

It however does not mention how to reset that code...to reset it I know that you need to push a specific set of buttons on a specific order...i do not know what they are or the order...

They are supposed to have full time customer support... here is the page for the numbers..you will have to call them for the reset code as it is not public knowledge...

http://www.takagi.com/?p=contact_us.php&page_id=7


heatman101

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Code 211 comes on but vent is clear of any debris or blockage. Sometimes can go days without alarm sounding sometimes alarm sounds 3-4 times in 10 minutes.

Generally tankless must be maintained on yearly basis.
Error codes are usually stored in the computer memory until they reach a threshold and then the error code is displayed... it is possible the control board is bad.. or the sensor that feeds information to the control board is bad.
Contact manufacturer or installer.
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Also on a T-K3 12 isn't a Code but a partial Code. You need an R/C to make this easier as counting led flashes produces wrong codes.
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My Takagi TK3 isn't heating as it should. Had a tech out and he adjusted the dip switches to 140 degrees, which worked for a while but now it barely heats to 100 degrees. Gas flow rate appears to be...

Is tankless computer older than 5 years? Imagine how well a 5-year old laptop computer works.

Setting temperature to 140 degrees might be the basic problem:
Read following resource:
http://waterheatertimer.org/Troubleshoot-Rheem-Tankless-water-heater.html#temperature

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http://waterheatertimer.org/Troubleshoot-Rheem-Tankless-water-heater.html#de-lime

Since you are not getting error code, the problem might be crossover, or some other plumbing problem:
http://waterheatertimer.org/Troubleshoot-Rheem-Tankless-water-heater.html#no-error
http://waterheatertimer.org/Crossover.html

I always recommend replacing tankless computer with tank-type water heater for $385 for same-day do-it-yourself solution and to save the endless expenses that arise with computer-driven water heaters.
http://waterheatertimer.org/How-to-install-gas-water-heater.html

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Hi,
First things... you have checked the inler filter andthe gas pressure, but have you checked and cleaned the thermistor(s)??? Also the flame sensor... clean that with a soft cloth...
Next turn down the temp with th dip switches that should tell you if it is the high limit...
Has the unit been cleaned with vinegar or CLR lately or ever??? there maybe buildup internally in the unit...
Is the flame a nice blue color or is it yellow???
Does it go out just before the unit cuts out???
Do the flames lift from the burner???

These are all things that I would be checking if I was coming to your home to check this unit...

Comment back with any other questions or comments...

heatman101
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