Abstract: In a first aspect of the present invention, a header for a heat exchanger is disclosed that has an inflow side, an outflow side, a bypass port therebetween, and a pressure-sensitive flapper valve proximal the bypass port. As pressure increases at the inflow side of the header, the flapper valve opens proportionally, and, as pressure decreases at the inflow side, the flapper valve closes proportionally. In a second aspect of the present invention, a tube-in-tube heat exchanger is disclosed that includes a helical tube-in-tube assembly adapted for flow therethrough of a plurality of fluids for heat transfer therebetween. In a third aspect of the present invention, a heat system is provided to include an embodiment of the header and an embodiment of the tube-in-tube heat exchanger, so as to provide a bypass of the tube-in-tube heat exchanger under a pressure condition.

Abstract: An underwater light, e.g., for a pool or spa, includes an ordinarily watertight housing, an outer compartment within the housing and floodable by water flowing therein in the event the housing is no longer watertight, a current shield within the outer compartment and at least partially defining an inner compartment within the outer compartment, a light emitter within the inner compartment, a passageway communicating between the inner and outer compartments such that outer compartment flood water can enter the inner compartment and contact the light emitter, and a conductor. The conductor is positioned so as to collect stray electrical current conducted from the inner compartment by water within the passageway, thereby reducing the risk of shock presented by such stray electrical current. The underwater light is installable within a wet niche, and includes a transformer housed in a separate compartment that extends into the wet niche for thorough cooling thereof.

Abstract: An underwater light, e.g., for a pool or spa, includes an ordinarily watertight housing, an outer compartment within the housing and floodable by water flowing therein in the event the housing is no longer watertight, a current shield within the outer compartment and at least partially defining an inner compartment within the outer compartment, a light emitter within the inner compartment, a passageway communicating between the inner and outer compartments such that outer compartment flood water can enter the inner compartment and contact the light emitter, and a conductor. The conductor is positioned so as to collect stray electrical current conducted from the inner compartment by water within the passageway, thereby reducing the risk of shock presented by such stray electrical current. The underwater light is installable within a wet niche, and includes a transformer housed in a separate compartment that extends into the wet niche for thorough cooling thereof.

Abstract: An underwater light, e.g., for a pool or spa, includes an ordinarily watertight housing, an outer compartment within the housing and floodable by water flowing therein in the event the housing is no longer watertight, a current shield within the outer compartment and at least partially defining an inner compartment within the outer compartment, a light emitter within the inner compartment, a passageway communicating between the inner and outer compartments such that outer compartment flood water can enter the inner compartment and contact the light emitter, and a conductor. The conductor is positioned so as to collect stray electrical current conducted from the inner compartment by water within the passageway, thereby reducing the risk of shock presented by such stray electrical current. The underwater light is installable within a wet niche, and includes a transformer housed in a separate compartment that extends into the wet niche for thorough cooling thereof.