After repairs or extensions to an existing hot water system, what is typically checked for leakage?

When repairs or extensions are made to an existing hot water system, it is important to check the system for leakage to ensure safety and functionality. Normal working pressure is the standard pressure at which the system operates under normal conditions. This is the pressure that the system is designed to withstand during regular use.

By checking for leakage at this pressure, technicians can identify any weak points or damaged fittings that may not have held during the initial installation or repair. This is crucial because leaks can lead to significant water loss, damage to the property, and potential hazards. Regularly operating pressure tests help ensure that the system can handle the volume and pressure it will experience during everyday operation without failures.

The other options, such as high-pressure testing, vacuum pressure, and substantial flow rate, are not the standard assessments used for this purpose. High-pressure testing is more about checking the strength and integrity of the system beyond normal operating conditions, vacuum pressure might pertain to specific applications rather than general leak testing, and flow rate is not directly associated with detecting leaks but more about system performance. Thus, focusing on the normal working pressure is key to maintaining the hot water system's reliability and safety.