Furnace construction

Claim 1

IN A FURNACE CONSTRUCTION, INCLUDING A CASING, A HEAT EXCHANGER IN THE CASING, MEANS TO PASS AIR TO BE HEATED OVER THE HEAT EXCHANGER THROUGH THE CASING, A BURNER FOR BURING FUEL IN THE HEAT EXCHANGER, SAID HEAT EXCHANGER AND THE ADJACENT VERTICAL WALL OF THE CASING FORMING A FLUE OPENING IN THE HEAT EXCHANGER AND IN THE CASING THROUGH WHICH THE PRODUCTS OF COMBUSTION MAY BE EXTRACTED, MOUNTING MEANS FOR THE HEAT EXCHANGER TO AVOID STRESSES IN THE HEAT EXCHANGER AND IN THE CASING DUE TO EXPANSION AND CONTRACTION OF THE HEAT EXCHANGER RELATIVE TO THE CASING COMPRISING A LOWER SUPPORT CARRIED BY THE CASING AND RIGIDLY FIXING A POINT ON THE HEAT EXCHANGER TO THE CASING AND SUPPORTING ADJACENT AN UPPER EDGE OF THE HEAT AND AN UPPER SUPPORT ADJACENT AN UPPER EDGE OF THE HEAT EXCHANGER COMPRISING A FLANGE LYING IN A VERTICAL PLANE AND SURROUNDING AND DEFINING THE FLUE OPENING IN THE HEAT EXCHANGER, A RECTANGULAR PLATE SECURED TO THE FLANGE, THE PLATE HAVING AN APERTURE REGISTERING WITH THE FLUE OPENING IN THE CASING, AND VERTICAL AND HORIZONTAL CHANNEL MEANS RESPECTIVELY CARRIED BY THE VERTICAL AND HORIZONTAL EDGE PORTIONS OF THE FLUE OPENING IN THE CASING TO HOLD THE VERTICAL AND HORIZONTAL EDGES OF THE PLATE IN SLIDING, SEALING RELATEION AGAINST THE CORRESPONDING VERTICAL AND HORIZONTAL EDGE PORTIONS OF THE FLUE OPENING IN THE CASING SO THAT THE PLATE MAY MOVE VERTICALLY UPWARDLY AND DOWNWARDLY DUE TO EXPANSION AND CONTRACTION OF THE HEAT EXCHANGER RELATIVE TO THE CASING WITHOUT IMPOSING STRESSES UPON EITHER THE HEAT EXCHANGER OR THE CASING.