Abstract: Methods and apparatus for manufacturing solar heating devices of a type having bonded together sheets of thermoplastic material forming a flexible wall container for fluid to be heated. The methods and apparatus involve advancing first and second elongate indeterminate lengths of sheet material longitudinally along respective paths while heating, bonding and sealing the sheets. Specific arrangements and steps for heating, bonding, and sealing are described.
Abstract: A solar heating device wherein a flexible-walled container of reinforced thermoplastic material serves as a solar fluid heater. The flexible-walled container is formed of fabric reinforced sheets of fluoroplastic material, such as polytetrafluoroethylene (Teflon) fusibly bonded together to provide fluid flow passages therebetween. Fluoroplastic materials are unaffected by outdoor weathering and have almost complete chemical inertness and are the slipperiest of all solids to provide low resistance to flow of fluid through the passages.