1. APPARATUS FOR MAKING METALLIC HEAT EXCHANGER CONDUITS WITH A WIRE COIL WOUND THEREON, COMPRISING DRIVE MEANS FOR CONTINUOUSLY ROTATING A CONDUIT TO BE WIRE-COIL WOUND AND FOR SIMULTANEOUSLY DISPLACING THE CONDUIT CONTINUOUSLY ALONG A PATH IN THE DIRECTION OF ITS AXIS, STATIONARY WIRE SUPPLY MEANS FOR SUPPLYING WIRE TO BE FORMED INTO A WIRE COIL, WINDING MEANS FOR FORMING THE WIRE COIL, SAID WINDING MEANS COMPRISING A WINDING MANDREL ADJACENT SAID PATH AND STATIONARY RELATIVE TO THE CONDUIT AXIS, SAID MANDREL HAVING A PERIPHERY COMPRISING A PLURALITY OF SURFACES, EACH OF SAID SURFACES BEING OTHER THAN A CONVEX SURFACE, AND WINDING MEANS ROTATABLE ABOUT SAID MANDREL FOR DRAWING THE WIRE FROM SAID WIRE SUPPLY MEAND AND FOR WINDING THE WIRE ABOUT SAID MANDREL IN THE FORM OF A WIRE COIL AND FOR SIMULTANEOUSLY EJECTING THE WIRE COIL FROM SAID MANDREL TOWARD THE CONDUIT FOR WINDING THEREON, MEANS FOR SUPPLYING A BAND OF SOLDER BETWEEN THE CONDUIT AND THE WIRE COIL SIMULTANEOUSLY AS THE WIRE IS WOUND ON THE CONDUIT, AND HEATING MEANS FOR HEATING THE CONDUIT AND THE WIRE COIL WOUND THEREON TO SOLDERING TEMPERATURE WHEREBY THE WIRE COIL IS SOLDERED TO SAID CONDUIT.