09-05-2012, 04:35 PM
The high limit thermostat that controls the high temperature on your AquaHot is located under the sheet metal cover just above the burner. You might consider joining Roger Berke's forum and asking your question. Roger will help you diagnose your problem.
http://forum.rvhydronicheaterrepair.com/forum.php
Steve Bare
1999 Newell 2 slide #531