Some gas water heaters use temperature cut-outs, such as the Watts 210 valve. This is a valve installed in the ______ line to the water heater.

The temperature cut-out, such as the Watts 210 valve, plays a crucial safety role in gas water heaters. This valve is specifically designed to be installed in the gas supply line to the water heater. Its function is to monitor the temperature of the water and, if necessary, shut off the gas supply to prevent overheating or potential hazards such as a gas leak or explosion.

When the water temperature exceeds a predetermined limit, the valve activates, cutting off the gas flow. This action helps ensure safety and protects both the appliance and the occupants of the home from the dangers associated with excessive heat.

In contrast, the other options refer to components or lines that serve different purposes. The water supply line is responsible for delivering cold water to the water heater, the drainage line is used for removing waste water, and ventilation pertains to the exhaust system designed to expel combustion gases. None of these lines serve the safety function that the temperature cut-out valve provides when installed in the gas supply line.