Suburban 6-Gal Hot Water Heater Emitting CO and minor smoke into cabin

[BagoBrave]

I have a '98 Winnebago Brave SE with a Suburban 6-Gallon hot water heater (propane) that occasionally emits a very minor exhaust smell (similar to what it smells like on the exterior when running) into the cabin. It sets off the CO alarm first, and if I move the CO alarm toward the water heater under the bed, the smoke alarm starts going off (it's a Kidde combo CO/Smoke detector).

This condition doesn't happen all that frequently, but happens when all windows are closed (so, it's not exhaust coming in from outside). There's no visible smoke, but it smells lightly like exhaust from the water heater, as it smells like outsie.

So far, I've looked in the compartment where the water heater is housed (under the bed), felt wires, looked for obvious damage, leaking water, etc; none of which is to be found.

I'm new to RV water heaters, so the problem and solution aren't coming to me intuitively. I've inspected the external hardware, tank, and the compartment, with nothing obvious to note. I just can't figure out how the smell and CO are getting into the cab since the combustion happens outside and the interior is the tank.

Any help would be great -- I could really be missing something obvious, and it's currently a safety concern.

[Shadowcatche]

The first thing to do is look at and understand the manual http://manuals.adventurerv.net/Subur...stallation.pdf
The heater should be sealed to the exterior so that no combustion gases can get inside, see page 3. My bet is this was not done or done incompletely.