Abstract: A method of assembling a heat exchanger having spaced fluid flow tubes and a normally flexible serpentine fin in each of the spaces between adjacent tubes in which the normally flexible fin is first assembled in a rigid, easy to handle unit by first attaching a heat conducting, elongated, rigid member to each set of serpentine crests on opposite sides of the fin to produce the relatively inflexible assembly in which the serpentine fin is held by the rigid members against bending followed by inserting each assembly between adjacent tubes and securing the assembly to the tubes. The disclosure also includes the heat exchanger assembled in this manner.

Abstract: A recuperator structure for recovering heat values from a hot gas stream comprising exhaust gases from a combustion burner supplied with combustion air for burning a fuel in which a heat exchanger is used for exchanging heat between the hot exhaust gases and the combustion air for preheating the combustion air and including a variable temperature control for selectively restricting the volumetric flow of either the air or the exhaust gases or both through the heat exchanger in order to control the temperature in the heat exchanger.One of the features of this invention is to provide a recuperator structure for recovering heat values by extracting heat in a heat exchanger from the hot exhaust gases from a combustion burner and using this heat in the exchanger to preheat the combustion air to the burner and including means for controlling the temperature in the heat exchanger by controlling the volumetric flow of either the combustion air or the exhaust gases or both through the heat exchanger.

Abstract: A heat exchanger device for recovering waste heat from a contaminated hot gas that carries solid and precipitable contaminants capable of being liquified by heat. The device has a heat exchanger with a plurality of spaced heat conducting passages for the contaminated hot gas and a plurality of spaced second passages for a cooler second gas with these first and second passages being alternately interleaved for efficient heat transfer and a heat conducting fin in each of the cool gas, such as air, passages for aid in transferring heat between the gases. The disclosure also includes means for selectively applying heat to the outer sides of the heat exchanger for transfer of liquifying heat to the deposited solid contaminants.

Abstract: A heat recovery device for recovering waste heat from a hot gas that carries solid and precipitable contaminants of the type given off from the grill area of a fast food restaurant in which a heat exchanger is provided through which these gases are directed for heat exchange with a gas to be heated such as ambient air. The heated air may then be supplied to the interior of the restaurant or to ambient. The two gases are directed through sets of spaced passages in the heat exchanger in heat exchange relationship with each other. A filter is used ahead of the heat exchanger for filtering the hot gas. This filter is easily removed for cleaning. A liquid receiving container may be periodically used to replace the filter. This receives a liquid such as a hot detergent solution that may be used to clean the contaminated passages of the heat exchanger.

Abstract: A recuperator structure for recovering heat values from a moisture laden hot gas stream and for utilizing these heat values to heat a space such as a room in which the structure comprises first, second, third, fourth, fifth and sixth ducts with the first, second and third ducts being used for conveying air from ambient to the space and having located therein heat exchangers and the fourth, fifth and sixth ducts communicating with the same heat exchangers for conveying a hot moist gas therethrough for heat exchange with the ambient air and then exhausting to the ambient, the result being that the hot moist gas gives up its heat values in the heat exchangers to the ambient air which is then exhausted in the resulting heated condition into the room.

Abstract: A recuperator structure for recovering heat values from a moisture laden hot gas stream that uses a plurality of heat exchangers having separated sets of passages through each in heat exchange relationship with each other, means for directing the hot gas stream through a first set of passages and means for directing ambient air through a second set of the passages and to a space for transferring heat to the space, means for precooling the hot gas stream upstream of the heat exchangers to condense moisture from the hot gas stream, means including separate ducts for arranging the heat exchanger and corresponding precooling means in first and second separate banks, flow control means in each duct for directing the hot gas stream selectively through the separate ducts while maintaining the other duct dormant and means for directing a heating medium through the precool means in the dormant duct to melt any frost remaining on the dormant duct precool means.

Abstract: A heat exchanger for exchanging heat between first and second gases such as for preheating the inlet air to a gas heating unit from exhaust air in which the exchanger comprises a core unit of a stack of generally planar serpentine fins each defining side-by-side gas flow passages between the adjacent side portions of the fins and means for mounting the stack of fins with some of these passages extending in one direction for a first gas and others of the passages extending generally transversely to the first gas passages for flow of the second gas in heat exchange relationship with the first gas, resilient gaskets at the edges of the unit for resiliently mounting the unit for yielding compensation for thermal dimensional changes and for sealing the gases from each other, a frame in which the unit is positioned with the frame comprising edge members engaging and bearing against the edge gaskets to apply pressure thereto and clamps for drawing the frame members together and toward the core unit to provide a rigi