Question about Rheem RTG-66DVN Direct Vent Natural Gas

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Tankless water heater error code 11

I continue to get an error code 11 in the digital temp setting display. I was on the phone with customer tech support several times yesterday- Inlet Gas = 7" w.c.; gas supply lines are 3/4" (24" of flex); shutoffs are all fully open; GFCI outlet grounded properly; 3"x5" Rheem concentric venting system. This is a RGV-66DVN unit. Any suggestions?

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  • gsx1000r02 May 05, 2009

    I have the same problem. The book says that the gas line isnt opened all the way. But mine is and both my stove and furnace work fine. So im not sure what the problem is or if there are any adjustments that can be made. If you find out anything please let me know



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I was having the same problem untill I reallized it was my venting system. Test the water heater with no vent on top. Disconnect the vent pipe from the water heater and try turning on the hot water. the water heater needs a special adapter to vent the direct vent water heater. One other thing you can check is the gas pressure in your home. You have to have between 7 and 8 WC (water Column) for the tankless water heaters. You can call your gas supplier to find out what you have.

Posted on Jul 04, 2009

  • Paul Apr 28, 2016

    You all have only 3 lbs f gas pressure through your house and is suficent to run your heater , the venting system is basic but critical to use the proper venting for it to work, it sounds like everything else you mentioned is correct


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I had the same code 11 with my Richmond tankless hot water heater.
The problem was with exhaust gasses getting sucked back into the intake tube. This robbed the combustion chamber of oxygen causing it to shut down. A simple adjustment to make sure those gasses could not mix at the intake/exhaust port fixed it.

Posted on Oct 25, 2009

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  • zmarshall81 Nov 09, 2010

    What did you do to make the adjustment?

  • sjboo May 10, 2011

    what did you do to fix it?

  • Danx73 Aug 13, 2011

    The code 11 on most Richmond tankless water heaters means that is is not getting gas. But, that is not the actual problem. The problem is actually just some dust on the sensors inside the unit; this is what rheem, the makers of these water heaters told me. If you call them they will email you the step-by-step instructions to fix it; it will be a PDF. I have it but cannot upload it here so you will have to call them. It will take about an hour, start to finish to get done.


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Do you have enough gas comming from the meter, just because the size is right doesn't meen the volume is there, you need to have 2lbs of gas going into the unit, the vent must be installed properly and locked together at each connection and out side the vent can not have anything in fornt of it to where the cold air intake wold pull the exhaust fumes back in when it is fired up, if it detects the burnt gas it will go into default and shut down because of the carbon minoxide comming thru the fresh air return good luck

Posted on Jun 06, 2009

  • zandar3 Aug 31, 2010

    2 pounds of gas pressure????? are you serious????

    propane gas pressure = 11 to 13 inches of water collumn.
    natural gasl pressure = 3 to 5 inches water collumn

    please get some training on gas systems and appliances!!!


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Had code 11 called rheem and they told me to toke the clear rubber hose that has an inner hose off the regulator thingy on the right hand side of the unit, look for any traces of water if there is even a misting of water push and hold the max butten on the circiut board while tube is disconneced and straightend towards the floor after several attempts i finnally got a hair dryer and got all of it out it now works fine. as for customer service i hgive them a a+

Posted on Feb 28, 2013

  • 391412 Jun 09, 2013

    #1 Thanks for the tip my richmond just went c2-11 just took a shower earlier just fine. I look here and yes the clear rubber hose was installed with a loop on purpose, I unlooped it and I cleared the water out and it started right up. It seems with the exhaust going up the same pipe as the air intake (double Stainless pipe goes to th roof) can suck down exhaust / blocking required combustable O2. from the fact it is working now, it must be pull O2 from the clear hose


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I fully opened the damper on my Rheem Tankless system, that seems to have fixed the problem. I guess it comes half closed. Anyone know why?

Posted on Oct 12, 2012

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  • Bill Oct 24, 2012

    Well, it is better, but not what it was/should be. Still have some issues once in a while.

  • TomG Feb 16, 2013

    How do you fully open the damper?

  • TomG Feb 16, 2013

    So where is the damper, and how do you fully open it?


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