In what type of system is unused hot water reheated along with cooler incoming water?

In a recirculating system, unused hot water is typically reheated along with cooler incoming water to maintain a consistent temperature and supply of hot water. This type of system is designed to provide hot water quickly and efficiently by continuously circulating water through the system. The mechanism allows for the reheating of remaining hot water that hasn't been used, ensuring that warmer water is readily available when needed.

In addition, recirculating systems help reduce water waste since they minimize the wait time for hot water at the faucet, since cooler water is mixed with the heated water before being sent to the tap. This system operates on the principle of maintaining water at a desired temperature, combining unused heated water with incoming cooler water to achieve that goal.

The other systems mentioned, such as direct, batch, and closed systems, do not typically involve the same process of continuous reheating of the unused hot water with incoming cooler water. Each of those systems has different characteristics and methods for delivering hot water that do not align with the mechanism described in the question.