In this video I’m walking through how I inspect an Aqua-Hot (and really, any hydronic heater like Oasis/ITR, Hurricane, Alde, even Truma-style systems) in a way that actually proves it’s working correctly—not just “it made hot water once.” I filmed this as part of my preventative maintenance series with Darren from My RV Works, because a lot of inspectors and owners never get a real step-by-step process in formal training. And let’s be honest: these systems are expensive and exotic—one control board can be hundreds of dollars—so you want to do this right. I start with the quick checks: electric element testing at the breaker panel with a clamp meter (I want to see current draw, around 10 amps), and a simple engine preheat check where you listen for the pump. Then we get into the money side: the diesel burner. I show you what I’m okay with (a little startup smoke for 10–15 seconds) and what’s a fail (smoke that keeps going after a couple minutes). From there, the inspection is about proving proper cycling and logic: it should heat to about 180°F, shut off, stay enabled, and not fire again until around 115°F. Finally, I force a demand by cranking all thermostat zones up (I go to 90°F), verify pump logic (stir pump vs loop pumps), and confirm the cozy heaters are actually producing heat—because the system has to do more than just “turn on.”