Like Second Chance we do not have one and do not know if one can be installed, as we too are very happy with the 12-gallon hot water heater in our 310GK. I will say this, my sister and brother in law have a Truma hot water heater in their trailer (not GD) and it failed on them which can happen to any product, but they had a hard time finding someone to repair it, when they did it still did not work. They finally got it repaired and it was quite expensive. This is only one case, so not saying it is a bad product, but apparently only "authorized" service facilities can handle repairs, while the Suburban hot water heater can easily be repaired. Just something to think about.