What condition should always be reported as a safety hazard in a gas water heater?

A TPR (Temperature Pressure Relief) valve without a proper pipe to the floor is critical to report as a safety hazard in a gas water heater. This valve is designed to prevent excessive pressure from building up within the tank, which could lead to an explosion. Without a proper discharge pipe directed to the floor, any discharge of hot water or steam from the TPR valve could cause scalding injuries or create a dangerous environment. The pipe is intended to safely direct the release away from occupants and structures, making the absence of this feature a significant safety risk.

While the other conditions such as a leaking tank, rusting in the heating chamber, and missing union fittings can pose issues—like potential water damage or reduced efficiency—they do not present the immediate and acute danger that a malfunctioning TPR valve does. A leaking tank can lead to water damage over time, rust may affect the longevity and performance of the heater, and missing union fittings may complicate repairs but do not constitute an immediate hazard. Thus, the absence of a proper discharge pipe for the TPR valve stands out as a top safety concern.