What technical order action should be followed to correct the self-help laundry's water heater if the water is too hot?

The correct course of action to take when addressing the issue of water being too hot in a self-help laundry's water heater is to test and service mixing valves. Mixing valves are designed to regulate the temperature of the water by blending hot water with cold water, ensuring that the output temperature remains within a safe and usable range. If these valves are malfunctioning or have not been adequately maintained, they may not properly mix the hot and cold water, leading to excessively hot water output.

By testing and servicing the mixing valves, you can determine if they are functioning correctly and make any necessary adjustments or repairs. This action directly impacts the temperature regulation of the water and addresses the root cause of the problem.

The other options, while they may relate to general maintenance and operations of water systems, do not specifically address the issue of controlling water temperature as effectively as servicing the mixing valves. For example, adjusting the thermostat might seem relevant, but if the mixing valves are faulty, simply adjusting the thermostat won't resolve the issue of water temperature consistency. Similarly, contacting HVAC personnel may not be necessary unless there is a broader issue involving air systems or central heating that is not limited to the water heating system. Partially closing the gate valve could restrict water flow, but it would