Page 303 of your owners manual shows the Aqua Hot diesel burner switch near the drivers area next to the engine brake and drivers shade switches.
Drvr Shade: Operates the power sun visor located driver’s
Brake: This switch activates the control solenoid for the engine
Aqua-Hot: Turns the Aqua-Hot diesel burner on.
If you download the digital copy of your owners manual you can perform searches by selecting Edit at the top, then about 3/4 of the way down select Find and type in the phrase or words you are looking for.
Link to download Holiday Rambler Manuals: https://www.holidayrambler.com/owners-manuals/