Mike,
My Aqua Hot is model 450-DE. It’s not original to the coach, it came with a Hydro-Hot I believe. I do have the manual for the Aqua-Hot.. In circuits 32,28,33 there are two high limit switches wired in series. Are these what monitor the temperature in the boiler and signal it to run and shut off? I’m assuming one is like a thermostat that cycles on and off and the other a safety feature that shuts the burner off if it reaches an unsafe temperature. Would these be found under the removable cover near the burner? I need to determine if these are working properly to so I can eliminate them as a possible cause, so I can determine if my “new” control board is defective. The burner worked fine for hot water with the old board, I just didn’t have coach heat.
Keith,
The antifreeze is at the proper level. I did have to hit the reset button to turn off the red fault light when I replaced the board.