essentially, it should be elevated anytime there is a possibility for combustibles(paper,liquids, etc.), to be stored adjacent to it. In practical terms that means that it should always be elevated except when in a dedicated closet.: A few months ago I saw a new program concerning the dangers of having hot water heaters installed on the floor because vapors from spilled materials could reach the flame. Are there any standards as to when the tank should be elevated? Our heater is in the basement next to the garage with a connecting door. Thanks