Ok.... now I am getting sustained hot water... over 10 minutes hot water in the shower. The only thing I did was move it out of or RV shelter and into the driveway so I could hook up to water and trouble shoot again with the repair people on the phone. It started up and operated normally. Here is my theory.... while parked under the shelter the hydro hot exhaust pile was only about 10 inches away from the shelter wall. This produced higher temps in that area that may have shut the system down. Does that make sense?