Abstract: Disclosed herein is a heat exchanger for altering the temperature of water from a fluid circulation line of a recreational body of water. The heat exchanger includes a helical tube-in-tube assembly adapted for flow therethrough of a plurality of fluids for heat transfer therebetween, and the heat exchanger further includes a tank defining a chamber in which said helical tube-in-tube assembly is positioned. In an exemplary embodiment, the chamber is an annular chamber, and the tank includes a cylindrical wall defining an external cavity extending through said tank.

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: A fin and tube heat exchanger includes fins shaped along dynamically, empirically determined isothermal lines. The fins preferably have deflectors along a trailing edge thereof to concentrate heat flux into a back row of tubes. The deflectors bridge adjacent fins to define baffles. The preferred fin shape may be obtained empirically by trimming fin areas exhibiting excessive temperatures during operation.

Abstract: A fuel/air mixture control for an induction heater having a tube-type burner includes a side-venting fuel nozzle for introducing fuel into an induction air stream entering the burner. A multi-speed blower draws combustion air into the burner and an air flow constrictor disposed proximate the fuel nozzle increases the velocity of the induction air stream proximate the fuel nozzle, increasing the volume of fuel introduced into the burner conduit. The fuel/air mixture depends upon the speed of the blower, which can be thermostatically controlled to increase speed upon sensing higher temperature combustion products, thereby maintaining a steady mass air flow and air/fuel mixture.

Abstract: A fluid heater includes a housing, a burner unit disposed in a bottom portion of the housing for burning combustible fuel, a combustion chamber disposed within the housing where the fuel is burned and a heat exchanger disposed substantially within the housing over the combustion chamber. The heat exchanger absorbs heat generated from burning the fuel and conducts the heat to a fluid to be heated. The heat exchanger includes a pair of spaced, parallel, stainless steel tubesheets with a plurality of tubes running therebetween and sealingly received within mating apertures in each of the tubesheets. A plastic front header and a plastic rear header are removably attached to the tubesheets distal to said tubes. The apertures in the tubesheets preferably have forged flanges for increasing the surface contact area with the heat exchanger tubes. The heat exchanger is corrosion resistant due to the combination of corrosion-resistant tubesheets, tubes and headers.

Abstract: The present invention is an access panel for a roof top air conditioning unit. The access panel edges interfit with edges of the air conditioner cabinet to form a tortuous path for entry into the cabinet interior. The tortuous path inhibits air, water, and moisture penetration. Also, insulating material is trapped between the interfitting edges to further block the penetration and insulate the cabinet interior. At the top edge, a lip extends downwardly to provide a positive stop to keep the removable access panel from laterally falling.