How do you vent the water heater? Any concerns about it scorching/igniting the wood above?
I have the same heater and mounted it in a similar location, not sure if it’s safe to use without the rear doors wide open.
The Excel Tankless heater is designed for inside use. No venting required. Not all tankless heaters are for inside use so pay attention to the requirements. I maintained all required clearances per the installation manual.