You had me at that frightening photograph ... that nearly happened to my church ... someone hadn't tightened a gasket after doing some work outside the church, and at the same time the hot water heater was malfunctioning, getting hotter and hotter while gas was floating around it. The electric heater didn't have a pilot, thank God, but the externals could have gotten up to 120 Fahrenheit. Gas ignites around 112, if memory serves! Any kind of spark -- a short in a light switch, for example -- would have been enough! Thank God that picture is not what happened to my church -- the deacons called the utility company and they got right out to help us!