Abstract: An air heating and ventilation system particularly suitable for well-insulated and draught-proof dwellings or buildings, there being provided a supply duct for fresh external air, connected to a main fan, a combustion chamber with an exhaust duct for the flue gases, an air heater disposed in the combustion chamber, a main distribution duct, feed ducts with controllable terminals for the rooms, a dirty air discharge duct provided with a fan, and a heat exchanger disposed between the supply duct for the outside air and the exhaust duct for the flue gases. The dirty air discharge duct is connected to the combustion chamber, so that dirty air at least in part acts as air for combustion and the remaining part is discharged together with the flue gases via the heat exchanger, the latter being adapted for transmitting the resulting condensate to the incoming external air.

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: Gas fired air heater for a central heating system comprising a heat exchanger in which are arranged a series of parallel rows of vertical heat exchange tubes, the lower ends of which are connected to a joint burner compartment and the upper ends of which are connected to a joint flue compartment. Two opposite lateral sides of the heat exchanger are connected to air supply and discharge compartments respectively for feeding the air to be heated transversely through the heat exchanger. The lateral air supply and discharge compartments have air inlet and outlet connections at their top and bottom walls only. One of said lateral air compartments is closed at one end and is connected to a fan at the opposite end, whereas at least one end of the other lateral air compartment is connected to a main duct for discharge of the heated air.