| 摘要 |
This invention mainly consists of a water tank with an additional heat exchanger installed at the exit of the water outlet of the tank. This heat exchanger is located inside the central tube of the water tank so that it receives heat from the same tank burner providing an additional surface area. This extra heat exchanger behaves as a tankless water heater receiving pre-heated water form the water tank. Therefore, the water from the tank receives additional energy as it crosses the additional heat exchanger. This idea incorporates the advantages of both tank and tankless water heaters and allows existing water tank owners to install a much better water heating system that can provide both large amounts of hot water initially followed by a endless limited supply of hot water, similar t o tankless systems. Another advantage of the system is that it increases overall efficiency of tank water heaters with the addition of extra heat exchanger surface. Additionally, it allows lowering the water heater tank average temperature, which reduces the heat losses associated with the hot water stored in the tank for long periods of time. The system needs heat modulation, but different than conventional tankless system that require burner control, it can be simply obtained by mixing utility cold water with warm water from the tank before entering the tankless part of the heater, keeping the outlet water temperature constant. The system provides endless supply of a fixed amount of water even when the water tank temperature has dropped to a certain level. When the burner is operating it heats both the water inside the tank and the water that leaves the tank, already pre-heated and as mentioned above.
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