| 摘要 |
Apparatus for protecting solar water-heating equipment against frost damage comprises a copper tube (14) within which an electrical heating element extends and a thermal switch connected to the heating element and disposed in a junction box (11) to switch on the heating element when the ambient temperature falls below, say, 2 DEG C and switches the element off again when the ambient temperature rises above, say, 5 DEG C. The tube may be coiled or bent to suit the shape of the item to be heated. The tube 14 may be clamped to or wound around the item, a heat conducting filler being interposed between the tube 14 and the item. Alternatively the tube can be inverted into the item. <IMAGE> |
