Abstract: A method and apparatus for assembling a fluid conducting tubular member into secure engagement with a channel integral with an elongated solar heat absorbing plate. The apparatus includes an elongated inflatable tube secured to an upstanding wall fastened to a table top. A fixture having a shallow V-shaped concave face is mounted on said table top with the concave face adjacent and parallel to said tube. An elongated plate having a channel parallel with the longer plate edges is positioned between the tube and the fixture with the channel opening toward the fixture. When the tube is inflated, it presses the plate toward the concave fixture surface. Plate edges contact and are restrained by the fixture edges, while the center of the plate is free to move further toward the fixture, flexing the plate in a manner increasing the diameter of the channel. A tubular member having an outside diameter equal to or greater than the unflexed channel diameter is inserted into the channel.