Mr Fix It Plumbing 4320 Atlantic Ave #230, Long Beach, CA 90807 (562) 988-2454 http://www.mrfixitplumbing.com/ A combustion air opening in an exterior wall of 1-sq.-inch for each 4000 Btu ranking of h2o heater is required in the higher and decreased 12 inches with the enclosure. Confirmed Workmanship: We stand https://holdenkexog.wikinstructions.com/930300/helping_the_others_realize_the_advantages_of_long_beach_plumbing