| 摘要 |
<p>Water heating apparatus of the invention comprises an inlet section (10, 140), an outlet section (11, 141) and a body (14, 139) between the two sections, the body (14, 139) containing a heater unit (26, 45, 124, 134, 137, 142, 149, 151, 155, 156, 160, 161, 162) including printed circuit heater means. In a preferred embodiment the heater unit (26) is in the form of a printed circuit heater (27) sandwiched between a pair of metal plates and rolled into a spiral. This gives a large contact area for water flowing around the spiral as well as an increased contact time, thus giving improved heating efficiency. In addition the printed circuit heater can be kept relatively short and compact, so that the water heating apparatus itself does not become bulky or expensive.</p> |
