Abstract: Coupling sleeve for the interconnection of hollow prismatic objects from sheet material, such as channel segments of an air heating device, said sleeve having a U- or W-shaped cross section, the limbs of this cross section having different length for facilitating the insertion of the edge of said prismatic objects into said coupling sleeve.

Abstract: A gas-heated hot water reservoir comprising a supply connection for fresh water and a discharge connection to an insulated distribution line for hot water leading towards a plurality of taps, said reservoir further comprising a gasburner and a pilot burner, the latter being positioned under a vertical passage through the reservoir with an annular space around it, bounded by an insulating wall secured to the bottom of the reservoir, an open-ended thin pipe accomodated within the distribution line between the annular space and a zone near the farthest tap.