CA2426723C - Megwaheater - Google Patents

Abstract

In a domestic gas water heater, it is necessary to exhaust the product of combustion through a flue. In this invention, combustion products generated by a burner pass through a flue, generally circular in cross section, is helically and coaxially composed of within the tank. This then comprises an upward spiral path for the combustible gases to be discharged. Properties of this embodiment cause the flue to provide excellent heat exchange with the water therein and to be heated through the large surface area exposed to the water. The gravitational flow of the exhausting hot flue gases causes high efficiency and markedly diminishes the overall gas consumption. In order to prevent heat loss in the standby mode, a damper provided in the flue on top of the water containing tank will be closed. This will maintain the heat retention within the flue and to cause the heat therein to further dissipate within the water to be heated.

Description

REFERENCES AND BACKGF:OUND ART
It is common with gas-operated war heaters to die the flue centrally through the crater tank, so that the hot gases from the combustion chamt~er are cooled as the rise up the Sue which is in contact with the water being heated. In order to enhance a letter best exchange befvreen the exhaust flue gas and the water within the tank, attempts have been made with ba6les in the exhaust fine. A
patent teaching such methods is U.S. Pat. No. 953,958 isseied in 1910. Sirxe then a great number of baffle structures have teen constructed. Examples a1 these are numerous and can be seen in U_S. Pat.
Nos. 4.742,8013, d,953,51t3, 1,859,745 and 5,544,625 these retard the hat gas in the Sue for a better heat exchange.A disadvantage of known flue baffles is that the xre mmpiex in oonstructian and many errors do ocau. t3Ren, not enoc;gh or boo may bathes can cause a very dar~rous oortdit'ron and can be costly to produce.
According to Jatana U.S. Pat. No. 4,641,631 and R>pka U.S. Pat No. 4,993,402 helical flues in a hot water heating apparatus ( as in hydronic heating systems j employ means such as an electrically operated tan to induce a draft through the flow path. The ac~diiional equipment is not a desirable arrangement to conserve energy. tt is,therafiora, a feature of the pre~M
invention to provide a flue for a gas-fired water heater which substarttialty overcomes the above-mentioned disadvantages witfiout any mechanical aperalirx~ embodirtrants.
Refs is made to a flue damper in Dietscha et <~1, U.S. Pat. No. 4,205,783 and outer related priorart applications as in Franker U.S. Pat. No. 4,039,123, Feinberg U.S.
Pat. No. 4,102,269 arid Sartac et al, U. S. Pat. No. 4,535,93!, disdasirrg a flue or vent damper in which the damps blade doses by an erectrically energized actuator when the furnace or water hNater is in the standby mode. Aecordirgly, during periods of no heat demand, the electrical actuator will be Wider a continuars toad of electrical currern until a demand for hot water or heating warrants the opening of the damper by interrupting the etectricat currant. This could involve fengthy peryads of strain on the electrical achsator.1n the event of a tnr~t-out actuator nr of de4aGMng ~ acxuetnr fa a signific:ent period of time, provision has been made to open the damper blade by a torsion spring for safety reesor~s.lt would be desirabre that the homer still operates.
This arrangenrertt is trot a wary desirable procedure for energy rvat'ron because much of the heat energy contained in the input fuel is not available to transfer efficiently and is cost "up the flue".
ft is, therefore, a fof the present invention to provide a flue for a gas-Erred water heater which substantiaity overcomes the above-mentioned disadvantages of the prior art.

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Thts lnVentiOn f9lat2S tf3 an i=n9rgy BffiCiBnt gaS wet&r YteatBf_ ~t t~a CoiTirt3on iii tf6YlC$S Such aS
gas water heaters that resultant exhaust gases Pram combt,stion must be vented through a flue. To dispose of combt~stic~n prc~duGfs produced i?y the burning g~3s, Ccanverrtiona! water heater flues are centrally located and contain a very inefficient vertical conc'uit to exhaust the product of combustion.
There is thus a need to improve the efficiency of gas water heaters in order to increase the overall efificiency of gas use. To extract heat energy firom relatively high temperature combustion gases, attempts are being made to increase efficiency by instaltirEC_: flue baffles to create turbulence and resistance of these gases to enhance heat exchange betwe~er: the flue and the water by having direct contact with an exterior surface tit the flue-ln U.S.Pat. No. 5,544,fi25, Riverr~ shows such a rrte~thod to absorb heat and exchange it with the liqc~id disposed thereabout with flue baffles- Nurr~erouS ofhE~r patents present irtventiQns in this regard, A
disadvantage of known flue baffles is that they are complex in construction and various errors do occur calculating the proper amount of baffles to ensure safe pasaage of exhaust gases.
! have found that these disadvantages may be overi:ome by providing an energy efficient clue to extract the heat energy from products of combustion discharged from me combustion chamber. The flue in this invention ex~ses a greater surface area; employinf! the ,~ Coanda"
effect ~wheras hot gases cling to a rising surface on their way up} thereby absorbing heat ~anergy and causing th>3 #!ue to provide excellent heat exchange with the gravitational flow for the water thereabout to be heated.
The ct~rrtbusfion products produced by burning pf t.!te gas-air mixture within the Gomt~tstion chamber pass through a flue of helical configuration extending upwardly from the combustion chamber, wheras the axis of the helical section coincides with the axi;> of the tank.
ii will be noted that the rising helicaf coil is of unifflrm cross-section from the beginning to the exi#ing location on top of the water tank.
Depending on the capacity of the water heater tank, the helical flue, preferably about three inches outside diameter O_D_ {about 7_6~ crrt.} has a #ent~th before exitirx~
tank of oboist 'l7.5r1 feet X5_34 meters}. The indicated length and diameter combined and s~ gas feed rate corresponding to about 4t3,0:~
BTUlffr. for a 42 Gallon U.S. water heater tank. provides ve y ef#icient heat transfer from the carrtbustion products tt~ the wafer to be heated. in drawing ~Fig: 1 } a tank draifl as wt'ii _as a corrtk~ination temperatureipressure relief valve are showing but are not numbered. In the preferred embodiment, the tank and the flue are either fabricated from a corrosion rest:>tant material or to be coated with a preferred iit>erglass-resin on those surfaces which are in contact with the water.
The flue camper assembly irt this invention ciffers in construction from illustrations of Dietsche et at_ U_S_ Pat. 4;20,783 in which an electrically energized actuator holds a flue damper on a pivotal shaft ceased during periods of no heat demand, opening the damlser in the absence of energiza6on_ To provide a particular texture in the application for insurance of fail-safe operation in the event of an eiectriGai failure in the damper circuit, a tiarsior~ spring wilt y?en tfie damper- T;rte arrangement to tepid a damper assembly of the type in which electrically energized actuator means holding a flue damper closed during periods of no heat demands, provides urtnecEtssary strain an components of electrical actuator in extended standby periods, warranting opening damper arrangement position by torsion spring for safety reasons-In this invention the electrically energized actuator, when energized, rotates the damper from closed to open and holds the damper plate open as long as energization continues, to the satisfaction of the temperature controller, i~nown as aquastat, to those skilled in the art.
Upon de-energization of the actuator, the electrical current to the damper motpr is interrt~tpted and an iraternaliy mounted retraction spring in the actuator reverses the motor to the arigina! states and causes the darriper plate on the pivotal shaft to be moved to the closed position. This eliminates ths~ flaw of the hot exhaust gases and retains them within the helical flue for an extended heat transfer to the water within the tank, efficiently conserving heat energy during periods of no-heat demands.

The damp9f plate COntffllling afm dlSengageS elBCtriCBl C~fIfaCtS in miCfo Switch when ttlB
damper plate is if: the dosed position, and interrupts the eti,ctricat current to the gas contro# valve extirtg~tishing the flame on the c~as burner to slap energy production in the hof water tank. This arrangement proves to be a potentially safe condition and rakes it impassible for the gas buyer to operate when the damper plate is in the closed position. Accordingly, no means of unnessesary strain is on the e3ectrica# components of the damper motor during periods of no-heat demands. #n this preferred arrangement the a#ecfica##y operated actuator is a premaru3factured embod#ment mouvir~g one-eig#~ of a turn stack-w#se through engrgization and returns to the original position employing the internal retraction spfing_ Accordingly, the aim of the invention is not only a v~sry high efficient heat exchange provided through the extra Length of the helical flue design, but also the desireable safety feature of the Closed damper plate in the standby periods when the entire a#ectric:at circuit automatica##y disrupts electrical currents through the satisfaction of the temperature controller.
#t is to be understood that cross references to Re#ated Applications have a#so contributed to the structure of me assemb#y as a who#e arsd the portico#ar cha~'actaristics of this irnrervt~on as a most 8fficient gas water heater_ DESCRIPTit~N 4F DRAi~iJtNG~
tn the drawings which i##ustrate embodiment of the invention, Fig_ 9 is an a#evation of the embodiment. trig. 2 is a side view Of the embodiment, Fig. 3 is the top view of the embodimen#, and Fig. 4 is the embodiment of the motorized damper assemt~ly. The:;e drawings were made with different aspects for better understanding and c#a~cation. All hidden compo~ients on the drawings afe indicated by perforated lines.
DETAILED DESGRIPTit~(~i ~~F CJi~AVIItNGS
Th8 gaS wat9r hBatBf tlluStfat~d by fefei9fiGe 1'7ilfrtt?~3f '~ COmpfiSBS 8 CfflSS-SACtiOn C3f t#ie wat$f heater elevation. Utilising gas, either natural or propane suftptied by a gas company, the gas #tows through the gas supply pig ~, regulating and controlling thf~ amount pf gas reqcrired by the gas 5urner for proper combustion is gas valve 3. This then employs gaa supply tubing 4 to the gas burner 5 into the combustion chamber 6 where the fuel is consumed by bumesr 5 and produces a product of combustion by uti#izing a gas pi#ot for ignition to ignite the combustib#e gay-air mixture emerging from the gas burner 5.
The comt~ustiOn products produced by burning Of the gas-air mixture within ttlA comtsustion chamber 6 pass through a heticatty and coaxial#y composed f#ue T
c~nranunicatir~g with the comtaustion chamber 6 is genefa#ty cifcu#af in crass-section wheras the ~~cis of the he#ica# flue coincides with the axis of the tank tt will be noted that the hellcat flue within the tack is of a substantially uniform cross-section from beginning to the end on top of tank at $_ l-leat energy is produced by burner ~ in combustion chamber 6 efFecting heat exchange as hot combustion gases pass through the helical flue 7, trasferring heat by conduction through the walls of the helical flue i to :~e exhausted on top of tank at 8.
The water temperature sensor 1'# assumes a purely mechanical form, such as an enclosed vo#ume of f#uid or bimeta##ic materia#, sa that at higher tempfsratures the f#uid or bimeta##ic materia#
expands and moves in one direction, whi#a at tower temperatures, the vo#urree decxeases,and the f#uid or bimeta##ic matefial moves in an opposite direction. >=xpansion of this afrafigement will open atsctricat contacts in temperature sensor 11 when the water temperature in the water tank ~ reaches the cut-out temperature, and closes the electrical cflrttacts in the tempe~_at~re sensor '! f as the water temperature in the hot water tank ~

reaches the cuf-in temperature and energizes the damper motor ~#Ci as explained heretofor has shown in Fig. 4~, to rotate tfle trldtt~fi 5tlaft of the electrical actuator with a permanently mounted metal arm 14 one eight of a turn in a ctoctc-wise direction trfitizing interrrtedi _atf; arrrt 't ~ tp contro# the damper p#afe cantrQ!ling arm 16 and relates tl~e damper plate 9 to the fully open position.
When ttte damper plate 9 reaches the fully open position, damper piste cantm#iing inn 16 will close contacts in the normally open micro switch 'i 7, energizing gas valve 3 to supply gas burner 5 with the gas-air mixture in corrabustican chamber 6 and starting the process of ersecgy product#on.
As hat water is being drawn from the water heater 1 through the hat water supply pipe 12, the same amount wi## be replaced by the city or water company under pressure through the cold water inlet pipe 13 which enters the hot water tantc 1 at atwut the same level as the temperature sensor 11. As sho~ttd be apparartt, this causes a very good mjxture of the wafer to be heated in the hot water tank 9, whereas the temperature sensor 11 closes the etectrica! co~~tacts immediately on the cut-in temperature sensing.
The energy source for the contro# system shown in Fig. 1 is in the form of a direct current at a re#ative#y #aw vo#tage from the standard housho#d current of '# 2U vo#t A.C.
which wi## be used as the voltage source, preferab#y stepped down by means of an is~~lating transformer to a retativety safe taw potential (on the order of 2~. volts). By using a low voltage, piny possibility of fatal atec#ric shock to the consumer should tae avoided, even if the water heater is located in a damp environment and even if some car all of the electrical CarnpOnentS of the control System have been improperly instattad, Such that tl~e operational voltage is exposed to the consumer.
In any event, the construction of the power supply reed not depart from conventional practices and may also be readily apparent to those ski#led in the art ~~rithQUt departing from the scope and spirit of the present invention.

The embodiment of the invention in which an exclusive property or privilege is claimed are defined as follows:
Claim 't - A hot water heater with a cormbustion type heater inclc~ding a combustion ~amt~.r under the tarZk and a flue for combustion gases passing through the tank and exiting the tap of said tank, wherein a motorized damper is mounted ai the exiting part of the flue on top of said tank and thereby extending the heat transfer to the water in said lank.
Ctairn 2 - A system as defined in claim 1 wherein ttse flue originates at the combustion chamt7er between the cEnter and the ~ripheral watt of the tank and passing through said tank exiting the top of said tank Claim 3 - A flue as defined in claim 2 wherein said flue comprising a hellcat configuration and the axis of the t~e_ lice! flue coincides wilts the a~cis of said tank.
Claim ~# = A flue as defined in claim 3 wherein Said helical flue is of uniform crass-section extending upwardly through said tank in a spiral cortfiguratian and exiting top of said tank.
Claim 5 - A hot water tank as defiined in claim i wttsrein a temperature controller in said hot water tank cormols water temperature in said hot water tan ~c and the damper actuator in the flue exiting the top of said hot water tank.
Claim B - A motorized flue damper on a pivotal sha~'k mounted in the exiting section of the hellcat flue arrangement an top of the hat water tank.
Claim 7 - A water temperature controller as cfaimetl in claim 5 which holds a flue damper on a pivotal shaft open in a flue pipe section through energizaticrt of the ftu~e darrtper actuator during periods of heat demand, and closes the flue r~amper by means of al3sence of energization.
Claim 8 - A motorized filue damper on a pivotal shan't as claimed in claim 6 closing by spring return action of electrical actuator on absence of enetgizati~an when water temperature reaches set-point on temperature controller controlling water temperature in t?~e hct water tartk_ Ctsim 9- A temperature controller as claimed irt claim 5 controlling the total electrical system on hat water heater to alt etectricat cammponents involved for the safe operation of the economical production of hot water fey energizingfdeenergizing damper actuator, e~ergizingldeenergizing gas control valve arid having the flue damper closed in the standby mode.

Claims (7)

1. A hot water heater comprising:
a water heating tank having a combustion chamber defining a burner cavity in a lower end of said tank, a combustion-type burner mounted in said burner cavity, wherein said burner cavity is cylindrical and coaxially disposed within said tank and said burner is coaxially disposed within said burner cavity under a cylindrical liquid filled reservoir within an upper end of said tank, a flue mounted within said reservoir so as to form a path for the transfer of combustion gases, which are the product of combustion by said burner, upwardly from said burner cavity through said reservoir to the atmosphere, wherein said flue originates at a flue inlet aperture in said combustion chamber between the centre and the peripheral wall of said tank so as to be offset from said centre of said tank, and wherein said flue is only helically and coaxially disposed along a helical portion within sand reservoir so as to extend helically upwardly through said reservoir to an exit at the top of said tank, and wherein said flue does not include baffles and wherein said hot water heater does not include a mechanical means for urging flow of said combustion gases along said path in cooperation with said flue, whereby said combustion gases flow upwardly through said flue so as to exchange heat to said liquid in said reservoir only by reason of said combustion gases being heated, an automatic flue damper for shutting off said flow when said combustion ceases.

2. The water heater of claim 1 wherein said automatic flue damper is a motorized damper mounted on said exit on top of said water heating tank.

3. The water heater of claim 2 wherein said flue damper is mounted on a pivotal shaft held open through energization of a flue damper actuator during periods of heat demand and closes by means of absence of energization.

4. The water heater of claim 3 wherein said flue damper further comprises an internal mounted return spring in said actuator so as to close said damper when in a standby mode.

5. The water heater of claim 1 wherein a temperature controller cooperating with said liquid filled reservoir controls the temperature in said reservoir and the total electric current to the electrical components on said water heating tank, and wherein a temperature sensor probe is mounted in a side wall of said reservoir adjacent said lower end, and wherein a cold water supply supplies cold water into said reservoir at a lower level also substantially adjacent said lower end.

6. The water heater of claim 5 wherein said lower level and said temperature sensor are substantially below said helical portion of said flue.

7. The water heater of claim 6 wherein said flue inlet aperture and said sensor are mounted so as to be substantially appositely disposed in said reservoir.