Abstract: This invention provides a thermal energy system comprising a heat exchanger for transferring thermal energy between a source and a load, the heat exchanger having a primary side associated with the source, and a secondary side for conducting a fluid associated with the load, wherein the secondary side of the heat exchanger is passively back-flushed upon consumption of a portion of the fluid. Passive back-flushing prevents fouling of the heat exchanger due to sediments, scale, and mineral deposits which may be present in the circulating fluid.

Abstract: This invention relates to a method and apparatus for a solar collector having intergral control of the maximum temperature that it can reach, thereby avoiding excessive stagnation temperatures in the collector.

Abstract: This invention provides a thermal energy system comprising a heat exchanger for transferring thermal energy between a source and a load, the heat exchanger having a primary side associated with the source, and a secondary side for conducting a fluid associated with the load, wherein the secondary side of the heat exchanger is passively back-flushed upon consumption of a portion of the fluid. Passive back-flushing prevents fouling of the heat exchanger due to sediments, scale,and mineral deposits which may be present in the circulating fluid.

Abstract: This invention relates to a method and apparatus for a solar collector having intergral control of the the maximum temperature that it can reach, thereby avoiding excessive stagnation temperatures in the collector.

Abstract: A thermal energy system including a heat exchanger for transferring thermal energy between a source and a load, the heat exchanger having a primary side associated with the source, and a secondary side for conducting a fluid associated with the load, wherein the secondary side of the heat exchanger is passively back-flushed upon consumption of a portion of the fluid. Passive back-flushing prevents fouling of the heat exchanger due to sediments, scale, and mineral deposits which may be present in the circulating fluid.

Abstract: This invention relates to a method and apparatus for a solar collector having intergral control of the the maximum temperature that it can reach, thereby avoiding excessive stagnation temperatures in the collector.

Abstract: This invention provides a thermal energy system comprising a heat exchanger for transferring thermal energy between a source and a load, the heat exchanger having a primary side associated with the source, and a secondary side for conducting a fluid associated with the load, wherein the secondary side of the heat exchanger is passively back-flushed upon consumption of a portion of the fluid. Passive back-flushing prevents fouling of the heat exchanger due to sediments, scale, and mineral deposits which may be present in the circulating fluid.

Abstract: A door closing device comprises a piston (12) having at one end a seal (21) which seals the interface between the piston and a housing (10). The seal (21) also acts as a one-way valve and carries a pressure relief valve (37).

Abstract: The piston of a door control device is assembled from a channel and cups welded on to opposite ends of the channel. A valve assembly is mounted in one of the cups. Rollers extend between opposite sides of the channel and co-operate with teeth on a rotatable member to which a control arm is secured.

Abstract: The piston assembly of a hydraulically controlled door closer has a tubular wall, plugs secured in end portions of the wall and a separate rack secured inside the tubular wall between the plugs by formations on the plugs.