| 摘要 |
Disclosed is a water heating system comprising: a hot water storage tank having a first port located in a lower region of the tank and a second port located in an upper region of the tank; a water flow pathway extending from the first port through a heating chamber to the second port; electrical heating means (for example a heating element) arranged to heat water within the heating chamber, when required, so that water within the water heating system will circulate from the first port to the second port through the heating chamber, by convection, when water is not drawn from the water heating system; a water supply outlet communicating with the water flow pathway intermediate the heating chamber and the second port; and a check valve arranged to restrict the flow of water out of the hot water storage tank by way of the second port when water is drawn from the water heating system through the water supply outlet. Therefore, when water is drawn from the system, the flow of water from the tank to the water supply outlet is restricted, and a much higher proportion of water passing through the water supply outlet has flowed directly from the heating chamber. Since water received at the water supply outlet directly from the heating chamber will have been more recently in contact with the electrical heating means than water received from the hot water storage tank via the second port, less electrical heating energy is required in order that water at a given temperature may be drawn from the system, or water drawn from the system will be at a higher temperature, than water drawn from a system lacking a check valve. Therefore, the system of the present invention is more efficient than a system lacking a check valve.
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