Error codes on Rheem RTG-74

Discussion in 'Tankless Water Heater Forum' started by edfiero, Jul 29, 2013.

  1. edfiero

    edfiero New Member

    Jul 29, 2013
    I have a Rheem RTG-74 Indoor LPG Unit. Its about 6 years old, and has worked flawlessly until a few months ago.

    1st problem - Water would never get hot on random occassions. Could not reproduce problem at will. Turning water off and back on usually solved issue. No error code seen on display, but no one around read the display while problem was happening.

    2nd Problem - a few weeks ago, Error code 13 on display. Would not re-set with simple Water on , Water Off, had to power on and off the main control. Error 13 reappeared next day. Took unit apart. Removed and reset Thermocouple on PCB and vacumned out the burner chamber. Issue has NOT returned.

    3rd problem (or maybe same as problem 1). I have now learned to look at the display when water does not get hot, I've observed ERROR CODE 12 multiple times. I have checked main gas pressure at 11+wc. (Since unit functioned in the same spot, unobstructed for 6 years, we can assume venting is all correct).

    What is my next step to resolve error 12? Is it the thermocouple that needs to cleaned, or is it the flame rods, or both? Can you describe the cleaning procedure? If cleaning is not an option and I need to replace these parts, can anyone provide the part number and a good source to purchase them at?
  2. edfiero

    edfiero New Member

    Jul 29, 2013
    4 years later and no reply? Lets bump this to the top and see if anyone has seen ERROR 12 on one of these Rheem units before?

    I cleaned off the front 3 flame sensing rods, but that did not solve the problem. Still get random error 12 which is resolved by shutting down the water and restarting it. Not much fun when you are in the middle of a shower.
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  4. Reach4

    Reach4 Well-Known Member

    Sep 25, 2013
    You have probably seen this list of codes and things to check:

    Some of them seem to point to power supply or electrical connections as a possible problem. If I had that symptom, I might wiggle connectors, and maybe power the system through my uninterruptible power supply that I use on my computer as a test for a while. I am not saying those are likely to help, but they seem like things I could try without knowing much about the system.
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