Gas fired fluid heating apparatus

Claim 2

Heating apparatus comprising an elongated upstanding combined exhaust stack and heat exchanger assembly having a plurality of generally coaxial elongated upstanding tubes including a first inner exhaust tube for receiving hot exhaust gases and to provide a longitudinally extending exhaust stack therefor, a second tube surrounding the first tube and defining therewith an inner longitudinally extending fluid passageway around the first tube, the first inner tube being formed with at least one helical convolution extending along a substantial portion thereof and providing corresponding helical grooves on the inner and outer surface thereof for causing generally swirling motion of the hot exhaust in the inner exhaust tube and generally helical flow of fluid around said inner exhaust tube, a third outer tube and a fourth tube intermediate the second and third tubes and defining therewith respectively longitudinally extending intermediate exhaust and outer fluid passageways.

Claim 3

Heating apparatus according to claim 1 wherein the fourth tube is formed with at least one helical convolution extending along a substantial portion thereof and providing corresponding helical grooves on the inner and outer surface thereof for causing generally swirling motion of the hot exhaust in the intermediate exhaust passageway and generally helical flow of fluid in the outer fluid passageway around said fourth tube.

Claim 4

Heating apparatus according to claim 1 further comprising a fluid inlet conduit connected to the loweR longitudinal end of the outer fluid passageway, a fluid outlet conduit connected to the lower end of the inner fluid passageway and a transfer conduit for conducting fluid between the upper ends of the outer and inner fluid passageways.

Claim 5

Gas fired apparatus comprising a gas fired water heater having an elongated combined exhaust conduit and heat exchanger assembly with exhaust inlet and outlet openings at first and second opposite longitudinal ends thereof respectively, a fire box with a fire chamber connected to the inlet opening, and means for conducting air and gas into the fire chamber for burning the gas therein, the combined exhaust conduit and heat exchanger assembly comprising a plurality of generally coaxial elongated tubes including an inner exhaust tube, an outer tube and first and second intermediate tubes defining therebetween an intermediate longitudinally extending gas passage and defining with the inner and outer tubes inner and outer longitudinally extending water passages respectively, water inlet and outlet conduits connected to the outer and inner water passages respectively at said first longitudinal end of the combined exhaust conduit and heat exchanger assembly, and a transfer conduit connected to conduct water from the outer water passage to the inner water passage at said second longitudinal end of the combined exhaust conduit and heat exchanger assembly.

Claim 6

Gas fired apparatus comprising a gas fired water heater having an elongated combined exhaust conduit and heat exchanger assembly with exhaust inlet and outlet openings at first and second opposite longitudinal ends thereof respectively, a fire box with a fire chamber connected to the inlet opening, and means for conducting air and gas into the fire chamber for burning the gas therein, the combined exhaust conduit and heat exchanger assembly comprising a plurality of generally coaxial elongated tubes including an inner exhaust tube, an outer tube and first and second intermediate tubes defining therebetween an intermediate longitudinally extending gas passage and defining with the inner and outer tubes inner and outer longitudinally extending water passages respectively, water inlet and outlet conduits connected to the outer and inner water passages respectively at said first longitudinal end of the combined exhaust conduit and heat exchanger assembly, and a transfer conduit connected to conduct water from the outer water passage to the inner water passage at said second longitudinal end of the combined exhaust conduit and heat exchanger assembly.

Claim 7

Gas fired apparatus according to claim 4 wherein the inner exhaust tube is formed with at least one helical convolution extending along a substantial portion thereof and providing corresponding helical grooves on the inner and outer surface thereof for causing generally swirling motion of the exhaust in the inner exhaust tube and generally helical flow of water around said inner exhaust tube along the inner longitudinally extending water passage.

Claim 8

Gas fired apparatus according to claim 5 wherein the second intermediate tube is formed with at least one helical convolution extending along a substantial portion thereof and providing corresponding helical grooves on the inner and outer surface thereof for causing generally swirling motion of the exhaust in the intermediate longitudinally extending gas passage and generally helical flow of water around said second intermediate tube along the outer longitudinally extending water passage.

Claim 9

Gas fired apparatus according to claim 4 wherein the outer tube and second intermediate tube have depending portions providing a housing of the fire box with a longitudinally extending water passage in communication with the outer longitudinally extending water passage.