Patent ID: 8747105

Claim:
A method of repairing a pre-heating tube arranged in an exhaust gas pathway of a fuel burner, comprising: providing an insert tube, having a first elastic sealing ring and a second elastic sealing ring disposed on an outside periphery surface of the insert tube, the insert tube having grooves defined therein on the outside periphery surface at each end on the outside periphery surface of the insert tube, the insert tube having an inlet and an outlet defined therein; providing a heated pre-heating tube having an inlet and an outlet; passing air, having a first temperature, from the inlet through the heated pre-heating tube and out through the outlet; leading air at the first temperature from the inlet channel at one side of the exhaust gas pathway and heating the air passing through the pre-heating tube by hot exhaust gases flowing externally to the pre-heating tube; the pre-heating tube heating the air for the fuel burner to a second temperature being higher than the first temperature; the preheating tube eroding, sliding the insert tube, having the first and second elastic sealing rings disposed in the grooves thereof, into the eroded pre-heating tube while compressing the first and second elastic sealing rings during insertion of the insert tube into the eroded pre-heating tube; the inserted and compressed first and second elastic sealing rings of the insert tube sealing air disposed in an insulation layer formed between the insert tube and the eroded pre-heating tube; the sealed air in the insulation layer raising the first temperature of the air at the inlet to a raised temperature, the insertion of the insert tube repairing the eroded pre-heating tube; and passing air, having the raised temperature, through the inlet of the insert tube disposed inside the eroded pre-heating tube and out through the outlet of the insert tube.