Question about Rinnai RHFE-431FAIII 16,700 BTU Direct Vent Furnace Energy Saver Heater - Natural Gas

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Rinnai Heater - error message "12"

Hi, we have a Rinnai 516TR. After the heater has been on a short while it stops and flashing a error message of "12" on the display. Nothing in our user guide says anything about error messages. We're lost and are sick of getting up every 5 mins to turn the heater back on! Help!

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  • drafang Jul 26, 2008

    We have the same probl;em and have cleaned the scren at the back - the online manusl says that we should check the thermocouple output, what is a thermocouple?

  • vanhaght Aug 03, 2008

    I have the same problem. I have cleaned (and washed) both the screens, the heater will work for a day or two then fault again. ??

  • ColdInKansas Aug 20, 2008

    Same problem: either code 11 or 12. Repair man came out and changed some board. Failed a few hours later, but now running 24 hrs without fault. Had the same problem with the boiler that the 53i replaced. I suspect problem with gas service. Guess I need to have them check pressure variations somehow before winter. Installer a bit short tempered about this.


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An error code of 12 on your heater means a flame failure has occured. It could be the following: Flame Rod dirty, Obstruction in burner, improper gas pressure, or a bad ignitor board. I am suggesting you get a technician who is familiar with Rinnai products to check out the above items.

Posted on May 27, 2008

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I fix Toyo's which are related to your heating unit. When a Toyo Laser 30 has an error code of 12, it means that the screen in the back is plugged up with lint, dust, or something causing the unit to over heat. A screen with what appears to be a little fuzz can be a significant clogging of the cooling air passive design of the system. Look for a lint screen and try cleaning it! Also, check out any info is the book about screen filters, fan shrouds etc in case your wording is diffrent. Toyo Tech

Posted on May 26, 2008

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I get this problem from time to time. It makes no sense. It happens randomly, and if I shut it off and turn it back on it comes right back up. Unfortunately this doesn't give us any peace of mind when leaving the house in the winter for a few days, or even when going to sleep when it's in the teens or single digits at night.

Posted on Jan 07, 2010

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