Mr Fix It Plumbing 4320 Atlantic Ave #230, Long Beach, CA 90807 (562) 988-2454 http://www.mrfixitplumbing.com/ A combustion air opening within an exterior wall of 1-square-inch for each 4000 Btu rating of drinking water heater is required inside the higher and decreased 12 inches of your enclosure. J&D Plumbing & https://maps.app.goo.gl/JAqevuQwVnnK5SJu6