Start with the water-heater model, energy source and whether the issue is no hot water, a leak or a control fault. Do not open gas, electrical or pressurized parts to gather information.
For a propane alarm or gas odor, evacuate without operating switches, the engine or generator, and get emergency or gas-supplier help from a safe place. For fire or suspected carbon monoxide, leave for fresh air and call 911. Stay out until emergency responders allow return.
