CA2499775A1 - Water heater flue gas heat recovery system - Google Patents
Water heater flue gas heat recovery system Download PDFInfo
- Publication number
- CA2499775A1 CA2499775A1 CA002499775A CA2499775A CA2499775A1 CA 2499775 A1 CA2499775 A1 CA 2499775A1 CA 002499775 A CA002499775 A CA 002499775A CA 2499775 A CA2499775 A CA 2499775A CA 2499775 A1 CA2499775 A1 CA 2499775A1
- Authority
- CA
- Canada
- Prior art keywords
- pipe
- assembly
- heat exchange
- flue
- water
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
- F28D7/00—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall
- F28D7/0041—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall the conduits for only one medium being tubes having parts touching each other or tubes assembled in panel form
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES
- F23J13/00—Fittings for chimneys or flues
- F23J13/02—Linings; Jackets; Casings
- F23J13/025—Linings; Jackets; Casings composed of concentric elements, e.g. double walled
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES
- F23J15/00—Arrangements of devices for treating smoke or fumes
- F23J15/06—Arrangements of devices for treating smoke or fumes of coolers
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
- F24H1/00—Water heaters, e.g. boilers, continuous-flow heaters or water-storage heaters
- F24H1/18—Water-storage heaters
- F24H1/186—Water-storage heaters using fluid fuel
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
- F28D21/00—Heat-exchange apparatus not covered by any of the groups F28D1/00 - F28D20/00
- F28D21/0001—Recuperative heat exchangers
- F28D21/0003—Recuperative heat exchangers the heat being recuperated from exhaust gases
- F28D21/0005—Recuperative heat exchangers the heat being recuperated from exhaust gases for domestic or space-heating systems
- F28D21/0007—Water heaters
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
- F28D7/00—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall
- F28D7/02—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall the conduits being helically coiled
- F28D7/024—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall the conduits being helically coiled the conduits of only one medium being helically coiled tubes, the coils having a cylindrical configuration
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES
- F23J2900/00—Special arrangements for conducting or purifying combustion fumes; Treatment of fumes or ashes
- F23J2900/13001—Preventing or reducing corrosion in chimneys
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES
- F23J2900/00—Special arrangements for conducting or purifying combustion fumes; Treatment of fumes or ashes
- F23J2900/13004—Water draining devices associated with flues
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24D—DOMESTIC- OR SPACE-HEATING SYSTEMS, e.g. CENTRAL HEATING SYSTEMS; DOMESTIC HOT-WATER SUPPLY SYSTEMS; ELEMENTS OR COMPONENTS THEREFOR
- F24D2200/00—Heat sources or energy sources
- F24D2200/16—Waste heat
- F24D2200/18—Flue gas recuperation
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E20/00—Combustion technologies with mitigation potential
- Y02E20/30—Technologies for a more efficient combustion or heat usage
Abstract
A flue gas heat recovery system for improving the thermal efficiency of a water heater. The flue gas heat recovery system is applied to a tank-type water heater. The flue gas heat recovery system comprises of a heat exchange assembly, a circulating pump, draft fan, piping, and a condensate drain pipe.
The circulating pump and draft fan start automatically when the water heater is in operation.
The draft fan allows the flue gas to overcome the pressure drop through the heat exchange assembly. The pump circulates water in a closed pipe loop between the water heating tank and the heat exchange assembly located in the flue pipe. Sensible and latent heat in the flue gas is transferred through the heat exchanger to the cold water being drawn from the water heating tank by the pump. The warm water is then returned to the water heating tank by the pump. Condensate in the flue pipe is directed to a drain pipe.
The flue gas heat recovery system could also be applied to an tankless water heater. No circulating pump is required since water heater operation and subsequent heat recovery only occurs when cold water is flowing. The preheated water is further heated as necessary by the tankless water heater.
The circulating pump and draft fan start automatically when the water heater is in operation.
The draft fan allows the flue gas to overcome the pressure drop through the heat exchange assembly. The pump circulates water in a closed pipe loop between the water heating tank and the heat exchange assembly located in the flue pipe. Sensible and latent heat in the flue gas is transferred through the heat exchanger to the cold water being drawn from the water heating tank by the pump. The warm water is then returned to the water heating tank by the pump. Condensate in the flue pipe is directed to a drain pipe.
The flue gas heat recovery system could also be applied to an tankless water heater. No circulating pump is required since water heater operation and subsequent heat recovery only occurs when cold water is flowing. The preheated water is further heated as necessary by the tankless water heater.
Description
Water Heater Flue Gas Heat Recovery System Background of the.lnvention Most tank-type or tankless water heaters have thermal efficiencies between 80 to 856. The remaining 15 to 20% of input energy is lost up the flue. These water heaters typically keep flue temperatures at a high enough temperature to prevent condensation.
Condensation occurs when water vapour within the flue gas changes from a gaseous state to a liquid state.
This condensate when mixed with other constituents of the flue gas is quite acidic and corrosive to any unprotected metal components. A properly designed flue gas heat recovery system can increase the thermal efficiency of a water heater by extracting useable heat from the flue gas while avoiding damage from condensation.
Various flue gas heat recovery systems have been proposed and commercialized to some degree as shown for example, in the following Canadian patents:
1267818 Granberg 1305897 Daugirda and Haag 2047355 Cifaldi 2430807 Campbell et al Commercial success of these systems has been limited given that most tank-type water heaters are purchased for low initial cost.
This invention has several advantages over other known heat recovery systems.
In particular, this heat recovery system can be retrofitted onto most tank-type water heaters and tankless water heaters. This permits manufacturers and existing users of water heaters to increase the performance of a conventional water heater. Furthermore, all the components of the heat recovery system are integrated together reducing installation cost and time.
Summary of the Invention This invention consists of a heat exchange assembly, circulating pump, draft fan, piping, and a condensate drain pipe. The heat exchange assembly is located external to the tank-type water heater and on the suction pressure side of the induced draft fan. The heat exchange assembly comprises of a section of flue pipe with an inner and outer surface.
The flue gas is in contact with the inner surface of the flue pipe. Fins located inside the flue pipe extend radially outwards and contact the inner surface of the flue pipe for improved heat transfer of energy from the flue gas to the outer surface of the flue pipe. Flue gas enters the inlet end of the heat exchange assembly and exits the outlet end of the heat exchange assembly. A
condensate drain pipe is located near the inlet end of the heat exchange assembly to prevent condensate from flowing back down into the water heater burner section. A
conventional stack pipe is connected to the discharge pressure side of the draft fan for discharge of the cooled flue gas to the outside.
The heat exchange assembly also comprises a section of flexible pipe encircling the outer surface of the flue pipe a multiple of turns. Water enters the inlet end of the flexible pipe and exits the outlet end of the flexible pipe. The flexible pipe is mechanically and thermally bonded to the outer surface of the flue pipe for heat exchange. The discharge pressure side of the circulating pump connects to the inlet end of the flexible heat exchange pipe. The suction pressure side of the circulating pump draws cold water from the water heating tank.
Warm water from the outlet end of the flexible heat exchange pipe is supplied back to the water heating tank. The thermostat in the water heating tank triggers the draft fan and the circulating pump to operate when heating is required.
Another embodiment of the invention has the heat exchange assembly and the draft fan located in the flue pipe of a tankless water heater. No pump is required to circulate water through the heat exchange assembly. When demand for hot water is present, a flow switch in the tankless water heater triggers operation of the heater and the draft fan.
Cold water is first directed through the heat exchange assembly to be preheated prior to entering the tankless water heater.
Condensation occurs when water vapour within the flue gas changes from a gaseous state to a liquid state.
This condensate when mixed with other constituents of the flue gas is quite acidic and corrosive to any unprotected metal components. A properly designed flue gas heat recovery system can increase the thermal efficiency of a water heater by extracting useable heat from the flue gas while avoiding damage from condensation.
Various flue gas heat recovery systems have been proposed and commercialized to some degree as shown for example, in the following Canadian patents:
1267818 Granberg 1305897 Daugirda and Haag 2047355 Cifaldi 2430807 Campbell et al Commercial success of these systems has been limited given that most tank-type water heaters are purchased for low initial cost.
This invention has several advantages over other known heat recovery systems.
In particular, this heat recovery system can be retrofitted onto most tank-type water heaters and tankless water heaters. This permits manufacturers and existing users of water heaters to increase the performance of a conventional water heater. Furthermore, all the components of the heat recovery system are integrated together reducing installation cost and time.
Summary of the Invention This invention consists of a heat exchange assembly, circulating pump, draft fan, piping, and a condensate drain pipe. The heat exchange assembly is located external to the tank-type water heater and on the suction pressure side of the induced draft fan. The heat exchange assembly comprises of a section of flue pipe with an inner and outer surface.
The flue gas is in contact with the inner surface of the flue pipe. Fins located inside the flue pipe extend radially outwards and contact the inner surface of the flue pipe for improved heat transfer of energy from the flue gas to the outer surface of the flue pipe. Flue gas enters the inlet end of the heat exchange assembly and exits the outlet end of the heat exchange assembly. A
condensate drain pipe is located near the inlet end of the heat exchange assembly to prevent condensate from flowing back down into the water heater burner section. A
conventional stack pipe is connected to the discharge pressure side of the draft fan for discharge of the cooled flue gas to the outside.
The heat exchange assembly also comprises a section of flexible pipe encircling the outer surface of the flue pipe a multiple of turns. Water enters the inlet end of the flexible pipe and exits the outlet end of the flexible pipe. The flexible pipe is mechanically and thermally bonded to the outer surface of the flue pipe for heat exchange. The discharge pressure side of the circulating pump connects to the inlet end of the flexible heat exchange pipe. The suction pressure side of the circulating pump draws cold water from the water heating tank.
Warm water from the outlet end of the flexible heat exchange pipe is supplied back to the water heating tank. The thermostat in the water heating tank triggers the draft fan and the circulating pump to operate when heating is required.
Another embodiment of the invention has the heat exchange assembly and the draft fan located in the flue pipe of a tankless water heater. No pump is required to circulate water through the heat exchange assembly. When demand for hot water is present, a flow switch in the tankless water heater triggers operation of the heater and the draft fan.
Cold water is first directed through the heat exchange assembly to be preheated prior to entering the tankless water heater.
Detailed Description of the Invention The first embodiment of the invention is directed at recovering usable heat from the flue gas being discharged by a water heating tank (1 ). The water heating tank (1 ) is fueled by either natural gas, propane or oil. Potable cold water enters the water heating tank (1 ) from the cold water pipe (2). Potable hot water leaves the water heating tank (1 ) from the hot water pipe (3). One end of a flue pipe elbow fitting (5) is connected to the flue gas outlet (4). The other end of the flue pipe elbow fitting (5) is connected to branch-end of a tee fitting (6). The lower through-end of the tee fitting (6) is connected to a condensate drain pipe (7) with optional trap. The upper through-end of the tee fitting (6) is connected to the inlet end of the heat exchange assembly (8). The given flue pipe arrangement allows any condensate generated by the cooling of flue gas to properly drain away without dripping inside the water heater (1 ).
The heat exchange assembly (8) comprises of a section of flue pipe (15) with an inner and outer surface. The flue gas is in contact with the inner surface of the flue pipe (15). Fins (16) located inside the flue pipe (15) extend radially outwards and contact the inner surface of the flue pipe (15) for improved heat transfer from the flue gas to the outer surface of the flue pipe.
Flue gas enters the inlet end of the heat exchange assembly (8) and exits the outlet end of the heat exchange assembly (8). To minimize corrosion, the entire heat exchange assembly (8) is fabricated from galvanized steel, stainless steel, bronze or any other heat resistant and corrosion resistant metal. The heat exchange assembly (8) is located with the axial length in a vertical manner.
The heat exchange assembly (8) also comprises a section of flexible pipe (17) encircling the outer surface of the flue pipe (15) a multiple of turns. Water enters the inlet end of the flexible pipe (17) and exits the outlet end of the flexible pipe (17). The flexible pipe (17) is mechanically and thermally bonded to the outer surface of the flue pipe (15) for heat exchange. The discharge pressure side of the circulating pump (9) connects to the inlet end of the flexible pipe (17). The suction pressure side of the circulating pump (9) draws water from the water heating tank (1 ) through the water heating return pipe (19).
Water from the outlet end of the flexible pipe (17) is directed back to the water heating tank (1 ) through the water heating supply pipe (18). During operation of the water heating tank (1 ) and the circulating pump (9), the temperature of the flue gas decreases while the temperature of the water increases through the heat exchange assembly (8).
The outlet end of the heat exchange assembly (8) is connected to one end of another flue pipe elbow fitting (10). The other end of the flue pipe elbow fitting (10) is connected to the suction pressure side of the draft fan (13). A stack pipe (14) connected to the discharge pressure side of the draft fan (13) directs the cooled flue gas to the outside. The draft fan (13) induces a slight negative pressure at the outlet of the heat exchange assembly (8) to allow the flue gas to overcome the pressure drop through the heat exchange assembly (8). A
dilution air opening (11 ) is located between the outlet of the heat exchange assembly (8) and the suction pressure side of the draft fan (13). The draft fan (13) causes dilution air to mix with the flue gas, ensuring that proper draft is maintained in the stack pipe (14). The draft fan (13) and circulating pump (9) is activated by an aquastat or thermostat in the water heating tank (1). A stand (12) supports the draft fan (13) and heat exchange assembly (8).
The second embodiment of the invention is directed at recovering usable heat from the flue gas being discharged by a tankless water heater (20). The tankless water heater (20) is fueled by either natural gas, propane or oil. Potable cold water enters the tankless water heater (20) from the cold water pipe (21 ). Potable hot water leaves the tankless water heater (20) from the hot water pipe (23). One end of a flue pipe elbow fitting (25) is connected to the flue gas outlet (24). The other end of the flue pipe elbow fitting (25) is connected to branch-end of a tee fitting (26). The lower through-end of the tee fitting (26) is connected to a condensate drain pipe (27) with optional trap. The upper through-end of the tee fitting (26) is connected to the inlet end of the heat exchange assembly (28). The given flue pipe arrangement allows any condensate generated by the cooling of flue gas to properly drain away without dripping inside the water heater (20).
The heat exchange assembly (28) comprises of a section of flue pipe (15) with an inner and outer surface. The flue gas is in contact with the inner surface of the flue pipe (15). Fins (16) located inside the flue pipe (15) extend radially outwards and contact the inner surface of the flue pipe (15) for improved heat transfer from the flue gas to the outer surface of the flue pipe.
Flue gas enters the inlet end of the heat exchange assembly (28) and exits the outlet end of the heat exchange assembly (28). To minimize corrosion, the entire heat exchange assembly (28) is fabricated from galvanized steel, stainless steel, bronze or any other heat resistant and corrosion resistant metal. The heat exchange assembly (28) is located with the axial length in a vertical manner.
The heat exchange assembly (28) also comprises a section of flexible pipe (17) encircling the outer surface of the flue pipe (15) a multiple of turns. Water enters the inlet end of the flexible pipe (17) and exits the outlet end of the flexible pipe (17). The flexible pipe (17) is mechanically and thermally bonded to the outer surface of the flue pipe (15) for heat exchange. During operation of the tankless water heater (20), the temperature of the flue gas decreases while the temperature of the water increases through the heat exchange assembly {28).
The outlet end of the heat exchange assembly (28) is connected to one end of another flue pipe elbow fitting (29). The other end of the flue pipe elbow fitting (29) is connected to the suction pressure side of the draft fan (32). A stack pipe (33) connected to the discharge pressure side of the draft fan (32) directs the cooled flue gas to the outside. The draft fan {32) induces a slight negative pressure at the outlet of the heat exchange assembly (28) to allow the flue gas to overcome the pressure drop through the heat exchange assembly (28). A
dilution air opening (30) is located between the outlet of the heat exchange assembly (28) and the suction pressure side of the draft fan (32). The draft fan (32) causes dilution air to mix with the flue gas, ensuring that proper draft is maintained in the stack pipe (33). The draft fan (32) is activated by a flow switch in the tankless water heater (20). A stand (31 ) supports the draft fan (32) and heat exchange assembly (28).
The heat exchange assembly (8) comprises of a section of flue pipe (15) with an inner and outer surface. The flue gas is in contact with the inner surface of the flue pipe (15). Fins (16) located inside the flue pipe (15) extend radially outwards and contact the inner surface of the flue pipe (15) for improved heat transfer from the flue gas to the outer surface of the flue pipe.
Flue gas enters the inlet end of the heat exchange assembly (8) and exits the outlet end of the heat exchange assembly (8). To minimize corrosion, the entire heat exchange assembly (8) is fabricated from galvanized steel, stainless steel, bronze or any other heat resistant and corrosion resistant metal. The heat exchange assembly (8) is located with the axial length in a vertical manner.
The heat exchange assembly (8) also comprises a section of flexible pipe (17) encircling the outer surface of the flue pipe (15) a multiple of turns. Water enters the inlet end of the flexible pipe (17) and exits the outlet end of the flexible pipe (17). The flexible pipe (17) is mechanically and thermally bonded to the outer surface of the flue pipe (15) for heat exchange. The discharge pressure side of the circulating pump (9) connects to the inlet end of the flexible pipe (17). The suction pressure side of the circulating pump (9) draws water from the water heating tank (1 ) through the water heating return pipe (19).
Water from the outlet end of the flexible pipe (17) is directed back to the water heating tank (1 ) through the water heating supply pipe (18). During operation of the water heating tank (1 ) and the circulating pump (9), the temperature of the flue gas decreases while the temperature of the water increases through the heat exchange assembly (8).
The outlet end of the heat exchange assembly (8) is connected to one end of another flue pipe elbow fitting (10). The other end of the flue pipe elbow fitting (10) is connected to the suction pressure side of the draft fan (13). A stack pipe (14) connected to the discharge pressure side of the draft fan (13) directs the cooled flue gas to the outside. The draft fan (13) induces a slight negative pressure at the outlet of the heat exchange assembly (8) to allow the flue gas to overcome the pressure drop through the heat exchange assembly (8). A
dilution air opening (11 ) is located between the outlet of the heat exchange assembly (8) and the suction pressure side of the draft fan (13). The draft fan (13) causes dilution air to mix with the flue gas, ensuring that proper draft is maintained in the stack pipe (14). The draft fan (13) and circulating pump (9) is activated by an aquastat or thermostat in the water heating tank (1). A stand (12) supports the draft fan (13) and heat exchange assembly (8).
The second embodiment of the invention is directed at recovering usable heat from the flue gas being discharged by a tankless water heater (20). The tankless water heater (20) is fueled by either natural gas, propane or oil. Potable cold water enters the tankless water heater (20) from the cold water pipe (21 ). Potable hot water leaves the tankless water heater (20) from the hot water pipe (23). One end of a flue pipe elbow fitting (25) is connected to the flue gas outlet (24). The other end of the flue pipe elbow fitting (25) is connected to branch-end of a tee fitting (26). The lower through-end of the tee fitting (26) is connected to a condensate drain pipe (27) with optional trap. The upper through-end of the tee fitting (26) is connected to the inlet end of the heat exchange assembly (28). The given flue pipe arrangement allows any condensate generated by the cooling of flue gas to properly drain away without dripping inside the water heater (20).
The heat exchange assembly (28) comprises of a section of flue pipe (15) with an inner and outer surface. The flue gas is in contact with the inner surface of the flue pipe (15). Fins (16) located inside the flue pipe (15) extend radially outwards and contact the inner surface of the flue pipe (15) for improved heat transfer from the flue gas to the outer surface of the flue pipe.
Flue gas enters the inlet end of the heat exchange assembly (28) and exits the outlet end of the heat exchange assembly (28). To minimize corrosion, the entire heat exchange assembly (28) is fabricated from galvanized steel, stainless steel, bronze or any other heat resistant and corrosion resistant metal. The heat exchange assembly (28) is located with the axial length in a vertical manner.
The heat exchange assembly (28) also comprises a section of flexible pipe (17) encircling the outer surface of the flue pipe (15) a multiple of turns. Water enters the inlet end of the flexible pipe (17) and exits the outlet end of the flexible pipe (17). The flexible pipe (17) is mechanically and thermally bonded to the outer surface of the flue pipe (15) for heat exchange. During operation of the tankless water heater (20), the temperature of the flue gas decreases while the temperature of the water increases through the heat exchange assembly {28).
The outlet end of the heat exchange assembly (28) is connected to one end of another flue pipe elbow fitting (29). The other end of the flue pipe elbow fitting (29) is connected to the suction pressure side of the draft fan (32). A stack pipe (33) connected to the discharge pressure side of the draft fan (32) directs the cooled flue gas to the outside. The draft fan {32) induces a slight negative pressure at the outlet of the heat exchange assembly (28) to allow the flue gas to overcome the pressure drop through the heat exchange assembly (28). A
dilution air opening (30) is located between the outlet of the heat exchange assembly (28) and the suction pressure side of the draft fan (32). The draft fan (32) causes dilution air to mix with the flue gas, ensuring that proper draft is maintained in the stack pipe (33). The draft fan (32) is activated by a flow switch in the tankless water heater (20). A stand (31 ) supports the draft fan (32) and heat exchange assembly (28).
Claims (20)
1. A water heater flue gas heat recovery system comprising:
- a tank-type water heater with an outlet to discharge hot flue gases - a heat exchange assembly consisting of a section of flue pipe and a flexible heat exchange pipe encircling said section of flue pipe - a circulating pump coupled to the inlet end of said flexible heat exchange pipe a water heating return pipe with inlet end coupled to said water heating tank, and outlet end coupled to said circulating pump - a water heating supply pipe with inlet end coupled to outlet end of said flexible heat exchange pipe, and outlet end coupled to said water heating tank - a draft fan located downstream of said heat exchange assembly
- a tank-type water heater with an outlet to discharge hot flue gases - a heat exchange assembly consisting of a section of flue pipe and a flexible heat exchange pipe encircling said section of flue pipe - a circulating pump coupled to the inlet end of said flexible heat exchange pipe a water heating return pipe with inlet end coupled to said water heating tank, and outlet end coupled to said circulating pump - a water heating supply pipe with inlet end coupled to outlet end of said flexible heat exchange pipe, and outlet end coupled to said water heating tank - a draft fan located downstream of said heat exchange assembly
2. The assembly of claim (1) includes heat transfer area augmentation fins coupled to inner surface of said section of flue pipe, and extending radially toward centre of said section of flue pipe.
3. The assembly of claim (1) includes a said flexible heat exchange pipe, mechanically and thermally bonded to outer surface of said section of flue pipe, encircling the entire length of said section of flue pipe in a spiral manner.
4. The assembly of claim (2) wherein said fins are fabricated from a heat resistant and corrosion material.
5. The assembly of claim (3) wherein said flexible heat exchange pipe is fabricated from a heat resistant and corrosion material.
6. The assembly of claim (1) further comprises of a flue pipe elbow fitting adapted into a flue pipe tee fitting located upstream of said heat exchange assembly.
7. The assembly of claim (5) includes a condensate drain located below the said flue pipe tee fitting.
8. The assembly of claim (1) further comprises of a flue pipe elbow fitting adapted into said draft fan located downstream of said heat exchange assembly.
9. The assembly of claim (8) includes a dilution air hood located upstream of said draft fan.
10. The assembly of claim (1) includes a plurality of members to support said heat exchange assembly and said dilution fan above said water heating tank.
11. A water heater flue gas heat recovery system comprising:
a tankless water heater with an outlet to discharge hot flue gases - a heat exchange assembly consisting of a section of flue pipe and a flexible heat exchange pipe encircling said section of flue pipe - a cold water supply pipe coupled to inlet end of said flexible heat exchange pipe - a preheated water supply pipe with inlet end coupled to outlet end of said flexible heat exchange pipe, and outlet end coupled to said tankless water heater - a draft fan located downstream of said heat exchange assembly
a tankless water heater with an outlet to discharge hot flue gases - a heat exchange assembly consisting of a section of flue pipe and a flexible heat exchange pipe encircling said section of flue pipe - a cold water supply pipe coupled to inlet end of said flexible heat exchange pipe - a preheated water supply pipe with inlet end coupled to outlet end of said flexible heat exchange pipe, and outlet end coupled to said tankless water heater - a draft fan located downstream of said heat exchange assembly
12. The assembly of claim (11) includes heat transfer area augmentation fins coupled to inner surface of said section of flue pipe, and extending radially toward centre of said section of flue pipe.
13. The assembly of claim (11) includes a said flexible heat exchange pipe, mechanically and thermally bonded to outer surface of said section of flue pipe, encircling the entire length of said section of flue pipe in a spiral manner.
14. The assembly of claim (12) wherein said fins are fabricated from a heat resistant and corrosion material.
15. The assembly of claim (13) wherein said flexible heat exchange pipe is fabricated from a heat resistant and corrosion material.
16. The assembly of claim (11) further comprises of a flue pipe elbow fitting adapted into a flue pipe tee fitting located upstream of said heat exchange assembly.
17. The assembly of claim (15) includes a condensate drain located below the said flue pipe tee fitting.
18. The assembly of claim (11) further comprises of a flue pipe elbow fitting adapted into said draft fan located downstream of said heat exchange assembly.
19. The assembly of claim (18) includes a dilution air hood located upstream of said draft fan.
20. The assembly of claim (11) includes a plurality of members to support said heat exchange assembly and said dilution fan above said tankless water heater.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002499775A CA2499775A1 (en) | 2005-03-15 | 2005-03-15 | Water heater flue gas heat recovery system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002499775A CA2499775A1 (en) | 2005-03-15 | 2005-03-15 | Water heater flue gas heat recovery system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2499775A1 true CA2499775A1 (en) | 2006-09-15 |
Family
ID=36998120
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002499775A Abandoned CA2499775A1 (en) | 2005-03-15 | 2005-03-15 | Water heater flue gas heat recovery system |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2499775A1 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE202009011326U1 (en) | 2008-08-20 | 2010-03-18 | Gwerder, Eugen | Heat exchanger for the flue gas duct of a furnace |
| CN111520913A (en) * | 2020-05-13 | 2020-08-11 | 重庆雨幻科技有限公司 | Water heater gap cold and hot water treatment device and control method |
| CN114322322A (en) * | 2021-12-29 | 2022-04-12 | 芜湖美的厨卫电器制造有限公司 | Gas water heater and control method, device and storage medium thereof |
-
2005
- 2005-03-15 CA CA002499775A patent/CA2499775A1/en not_active Abandoned
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE202009011326U1 (en) | 2008-08-20 | 2010-03-18 | Gwerder, Eugen | Heat exchanger for the flue gas duct of a furnace |
| AT12668U1 (en) * | 2008-08-20 | 2012-09-15 | Gwerder Eugen | HEAT EXCHANGER FOR THE SMOKE GAS CHANNEL OF A FIRE |
| CN111520913A (en) * | 2020-05-13 | 2020-08-11 | 重庆雨幻科技有限公司 | Water heater gap cold and hot water treatment device and control method |
| CN114322322A (en) * | 2021-12-29 | 2022-04-12 | 芜湖美的厨卫电器制造有限公司 | Gas water heater and control method, device and storage medium thereof |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Dead |