Wood burning boiler

Heating apparatus comprising:

• a) stove means having a plurality of side, top and bottom walls, wherein said walls enclose a first cavity and wherein at least one of said walls includes an acess port to the first cavity and at least one of said walls includes an exhaust port to the first cavity, for containing a fire within the first cavity;
• b) heat exchange means having a plurality of walls secured to and surrounding said stove means to define a second cavity for containing a thermal transfer medium to contact the walls of said stove means without communicating with said access and exhaust ports;
• c) door means for covering said access port and comprising 1) an external metal panel, 2) a first metal panel including first and second intersecting bends, 3) a first pin extending from the external panel and through a first aperture at an intersection of the bends panel and wherein the first panel subtends an air space between the first and external panels, 4) a second metal panel having second and third apertures, 5) an insulator layer mounted between the first and second panels, 6) second and third pins offset from said first pin and extending between the first and second panels through said second and third apertures, and 7) wherein at least one of the first and second panels flexes along said first, second or third pins with thermal changes in said first cavity, whereby said external, first and second panels are substantially thermally insulated from one another and said first and second panels are able to flex independent of one another without transferring panel flexion to cause warpage of the external panel;
• and
• d) flue means communicating with said exhaust port for exhausting combustion gases.

Heating apparatus comprising:

• a) stove means having a plurality of side, top and bottom walls, wherein said walls enclose a first cavity and wherein at least one of said walls includes an access port to the first cavity and at least one of said walls includes an exhaust port to the first cavity, for containing a fire within the first cavity, wherein a plurality of conduits extend through the first cavity above a fire space, wherein each conduit has a bore exposed through one of said side walls, and wherein the top wall includes a recess which extends into the first cavity in a space between said conduits and the exhaust port;
• b) heat exchange means having a plurality of walls secured to and surrounding said stove means to define a second cavity for containing a thermal medium to contact the walls of said stove means and to flow through the bore of each of said conduits without communicating with said access and exhaust ports;
• c) door means for covering said access port and comprising 1) an external metal panel, 2) a first metal panel, 3) a second metal panel, 4) means for thermally insulating said external panel from said first panel and the first panel from the second panel, 5) first fastener means for restraining said first panel to said external panel, 6) second fastener means offset from said first fastener means for restraining said first panel to said second panel, and 7) wherein at least one of said first and second fastener means comprises a pin which projects from one of the external or first panels and loosely extends through an aperture at the other of the first or second panels such that the other of the first an second panels flexes along said pin with thermal changes in said first cavity, whereby said external, first and second panels are substantially thermally insulated from one another and said first and second panels are able to flex independent of one another without transfering panel flexion to cause warpage of the external panel;
• and
• d) flue means communicating with said exhaust port for exhausting combustion gases and including means for removing liquids formed within said flue means.