The 3-burner stove with oven is also the heater! It is a Duette brand unit. It is vented to the exterior, with a lower intake (combustion) vent and a shielded upper (exaust) vent located just below the kitchen window.
The Duettes were a very good idea, I had one. They were discontinued a long time ago, as quite a few trailers, and motorhomes, caught fire, from the Duettes.
The exhaust pipe through the wall, got dislodged, accidentally, due to road travel, or by mistake, or was too near the wall for such a hot exhaust pipe !
Also the vent didn't need to be anywhere near a window, that might be open. It needed a lot of non-flammable insulation.
Please be very careful with it.