| 摘要 |
The water heater comprises an upper and lower reservoir 12 and 10 in which cold water is stored in the upper reservoir 12 for feeding the lower reservoir 10 which contains a heater 40. An interconnecting passage 14 transfers cold water from the upper reservoir 12 to the lower reservoir 10 to maintain the level therein. An expansion pipe 16 permits heated water forced out of the lower reservoir 10 by expansion to return to the upper reservoir 12. The expansion pipe 16 is thermally separated from the water in the upper reservoir 12 to prevent heat from the pipe 16 warming up the water in the upper reservoir 12 sufficiently to allow harmful bacteria to form. The pipe 16 may be insulated by means of a sleeve of thermally insulating material surrounding and either in or not in contact with the pipe 16. Alternatively, a sleeve 18 surrounds the pipe 16 with an air gap and a drain may also be provided for draining this gap of any water which collects in it. The pipes 14 and 16 may be made of a material which is resistant to heat flow or be provided with insulating collars (26, 28 Fig. 2). Temperature sensing, audible or visual alarm and control arrangements may also be provided to indicate when the temperature of the water in the upper reservoir 12 has exceeded a predetermined limit. |
