Abstract: A differential-temperature-sensitive device particularly useful for controlling an electrical switch in response to a difference in temperature comprises a first lever arm pivotably mounted at one end to a base member, a second lever arm pivotably mounted to the opposite end of the first arm, and a pair of temperature-sensitive elements each coupled to one of said lever arms for pivoting same in response to the temperature sensed, the control member, preferably an electrical switch, being actuated by the opposite end of the second lever arm.

Abstract: A solar collector using a basic element suitable for modular construction is described, comprising an absorber panel including a plurality of metal extrusions attached together in the direction of the width of the panel, and further metal extrusions each cut along a diagonal line and attached to the opposite ends of the absorber panel to form the inlet and outlet manifolds. The solar collector further includes transparent window panels attached to the housing frame by a mounting having a resilient partition facing the absorber panel to partition the space between the transparent panel and the absorber panel and thereby to reduce convection losses.