Abstract: The present invention relates to the making of an evaporator or condenser construction wherein ends of heat exchange tubes extending through heat exchange plates or fins are joined with return bend connectors. The ends of the tubes are provided with flared cups that telescopically receive the ends of return bend connectors. Nibs are formed on the outer surface of and extend outwardly a predetermined amount from the outer surface of the return bend connectors near the ends thereof. Grooves are formed on said outer surface and extend longitudinally between each nib and the end of the connector. When the end of a return bend connector is inserted into a flared cup, an interference fit between the nibs and the cup centers the end of the connector in the cup and frictionally retains the tube and the return bend in assembled relation when the assembly is inverted and thereafter submerged in a solder bath. The grooves provide vents for hot gases during the soldering operation.