Abstract An illustrative embodiment of the invention is directed to a thermally insulated exhaust duct structure. In this regard, a typical duct comprises an inner stainless steel conduit and one or more sheets of highly-reflective material that are spirally wrapped around and spaced outwardly from the outer surface of the conduit. The adjacent layers of the sheet material, moreover, are spaced from each other a predetermined distance through corrugated strips that are fastened to one side of the sheet material. Thus, when wound about the conduit in an overlaying relationship, the corrugation peaks bear against the sheet of material that is immediately below and thereby estabish a spacing between adjacent layers that is at least equal to the depth of the corrugations. Other features of the inventon include an outer protective stainless steel casing that fits over the spirally wrapped insulating sheet and a roof penetration for the duct structure.
A stack comprising a plurality of stack segments, each of said stack segments having a centrally disposed generally cylindrical conduit, a plurality of foils, each of said foils being individual to a respective one of said conduits, at least one foil wound at least twice about the outer surface of at least one of said conduits in a generally spiral path to produce a plurality of layers, each of said layers in said spiral winding being spaced from the next adjacent layer, said conduits each having at least one transverse end thereof tapered to mate with and engage the transverse end of the next adjacent conduit, at least one expansion joint in communication with said stack segments, said expansion joint having two axially aligned conduits that are axially spaced from each other, a collar bridging across said conduits and said spacing therebetween, said collar being secured to only one of said conduits, another foil wrapped around the outside of said conduits and said collar in a spiral path into a roll of said another foil, each layer of said another foil being spaced a predetermined distance from adjacent layers thereof, and a casing extending beyond the extremities of said foil roll.
Claim 2
Dependent Claim
201 words
A stack comprising a plurality of stack segments, each of said stack segments having a centrally disposed generally cylindrical conduit, a plurality of foils, each of said foils being individual to a respective one of said conduits, at least one foil wound at least twice about the outer surface of at least one of said conduits in a generally spiral path to produce a plurality of layers, each of said layers in said spiral winding being spaced from the next adjacent layer, said conduits each having at least one transverse end thereof tapered to mate with and engage the transverse end of the next adjacent conduit, at least one expansion joint in communication with said stack segments, said expansion joint having two axially aligned conduits that are axially spaced from each other, a collar bridging across said conduits and said spacing therebetween, said collar being secured to only one of said conduits, another foil wrapped around the outside of said conduits and said collar in a spiral path into a roll of said another foil, each layer of said another foil being spaced a predetermined distance from adjacent layers thereof, and a casing extending beyond the extremities of said foil roll.