US2039910A - Dual oil burner control system - Google Patents

Description

May 5, 1936. J. P. KRIECHBAUM DUAL OIL BURNER CONTROL SYSTEM Filed Oct. 16, 1933 JOHN P. KRIECHBAUM' Patented May 5, 1936 UNITED STATES PATENT OFFICE DUAL OIL BURNER CONTROL SYSTEM John P. Krlechbaum, Minneapolis, Minn.

Application October 16, 1933, Serial No 693,756 7 Olaims. (01.158-28) The present inventlon relates to the art of automatically burning fuels particularly for the heating of homes and the heating of water to be used therein for domestic purposes.

One of the objects of the present invention i's the provision of means for controlling the supply cf fue1 to any one of a, plurality of burners and simultaneously supplying combustion supporting air t at least those burners which are in operation, together with means rendt'ered operative upon operation cf any' one of the burners for maintaim'ng the supply of combustion supporting air for a, period after cessation of operation of all cf said burners.

More particularly, the means for maintalnlng the supply 0\f combustion supporting air to the burners comprisias a thermostatic switching mechanism responsive to the temperature of combustion produced by any or all of the burners and which includes a, switch which opens upon a fall in temperature Whereby the supply of combustion air is malntained until the temperature of combustion -falls ab least a predetermined amount a.s a result"of cessaion o'f operation of all of said burners.

A further. object of the invention 15 the provision of two or more heaters f or heating different devices, objects er mediums and means for coutrolling the supply 0f fuel to each of the burners in accordance With changes in the ccmditions produced er controlled by the burners and simultaneously supplying combustion supporting alr thereto together with auxiliary means rendered operative upon operation of any one o:t' the bumers for maintaining the supply o& combustion supporting air for a period after cessation of operatiofi of all oftheburners.

A further objectof the invention is the provislon of two er more heating devices which are all connected to a common stack for the passage of the gases of combustion f1 um the various bumers and means respcnsive to conditions produced by operation of the burners for controlling the supply of fuel a.nd cqmbustion supportlng air thereto, together with means responsive to the temperature cf the gaseS of combustion passing through the common stack for the various bumersfor maintaim'ng the supply of combustion supporting air to at least those burners which are in operation for a period after the c8ssation of combustion of the last of the burners to be in operation. Sr cifically, one of the heating devices is utilized to heat a space or dwelling and the other' of the heating devices heats a supply 0I hol: water Ior use in thespac e or dwelling heated by the other of the heating devices. Also, preferably, the control system is completely electrical and the means responsive to thetemperature cf the gases in the common stack is a combustion temperature responsive switch which is operated upon temperature reversals and o:pens when the tempera-. ture of the .combustion gases passing through the stack has decreased at least a.- predetermined amount.

Another object of the invention is the provision 10 of a simple inexpensive control system by means 0f which the supply of fuel 130 a hea.ter is varied or stopped or started in accordance with the beating demands but in which the supply of combustion supporting air is initiated when the heater is placed in operation and is prolonged fo1 a. period after the supply of fuel is decreased or shut oif.

Other objects will be found in the following detalled descripticm, the accompanying drawing and the appended claims.

Referring to the single fig'ure of the drawings, a. heating device generally indicated at I0 for heating a space such as a dwelling is herein shown as eomprising the usual warm air furnace,

but lt is to be understood that any other wellknown type cf heating apparatus could be utilized in its place. The warm air furnace I0 is Drovided with the usua1 combustion chamber II ahd an air heating chamber I2. The frnace I0 is herein illustrated as being heated by a liquid fuel burner generally indlcated at I3 which comprises a circular combustion pot I4, located within the combustion chamber II and. .adapted 150 receive a supply 015 liquid fuel from a, pipe I5 which is controlled by an electric valve I6 of any wellknown constructlon.

The furnace I0 is provided with a fan I'I for producing a clrculation 0f air through the 2.11

heating chamber I2, 0 1i; headers I8 and to the 40 room or spa.ce to be lieated. The fan I'I is herein shown as located in the cold .LiI intake I9 of the furnace I0 and is adapted po be driven by an electric motbr 20. v

A the1mostatlc switching mechanism'iesponsive to the temperature of the air in the a.ir heating chamber I2 is generally indicated. ab 2I and comprises a casing 22, a tubular extension 23 by means of which the switching mechanism is' ser ranged that II; is normally closed, as shown in the drawing and on1y opens when the temperature of the air in air heating chamber I2 becomes excessive and will hereinafter be referred to as the high limit switch. The switch 21 is so airanged that it opens and remains open whenever the temperature of the air inair heating cha.mber I2 is at or below some predetermined minimum value say, 150 F. and will hereinafter be referred to as the fan switch. Such switching mechanisms are well-known in the art and need no further detailed explanation.

A water heater is herein shown as a furnace 30 within which is located a liquid fuel burner having a circular combustion pot 3I adapted to receive a supply of liquid fuel from .a pipe 32 which is controlled by an electrioally operated valve 33 of any of the usual constructions. Wlthin the heater 30 'is located a pipe coil 34, the upper end of which commumcates with the upper end of a water storage tank 35 and the lower end 015 which communicates with the lower end the1eof. The water storage tank 35 is provided with an in1et pipe 36 by means of which the tank 35 and pipe coil 34 are provided with a supply of cold water as needed. The storage tank 35 is further provided with a hob water outlet pipe 31 which may be connected to the domestic bot water supply pipes in the usual manner. A thermostatic switch, generally indicated at 38, is quite'similar in construction to the switching mechanism 2I in that II: oomprises a casing 39 havin'g atubular extension 40 by which the casing 39 is secured. 1:0 the water tank 35, a helically coiled thermostatlo element 4l located within the tank 35 and having one of its ends secured to extension 40, and a torsion rod 42 which extends into and terminates 'within casing 39 am]. is seeured to the other end of thermostatic element 4I. Within the casing 39 and operated by torsion rod 42 Is a mercury switch 43 of well-known construction, the mercnry switch 43 being so arranged that II. closes a circuit when the temperature of the water in the water tank 35 is at or below some predetern'iined. minimum temperature say 160'-F;

A common stank 45 is connected to the combustion chamber of the warm air furnace I by means of a pipe 46 and is connected to the combustion chamber of the w'ater heater 30 by means of a. pipe 4I. Associated with the common stack 45 is a draft concrolling device herein shown as a draft fan 48 located within the common stack 45 and. driven by an electric motor 49. Also associated with the common stack 45 is a thermostatic switching mechanism generally indica.ted at 50 which comprises a casing I, a, tubular extension 52, a, helically coiled thermostatic element 53, and a torsion rod 54. One end of thermostatic element 53 is secured to tubular extension 52 and the other end thereof Is secured 130 torsion rod 54. The torsion rod 54 terminates within casing 5I and is conneeted to a. mercury switch 55 located therein by the usual welI-known neu-positive transmission means o1 slip friction connection whereby the mercury switch 55 Is operated upon temper'ature reversals rather than at predetermined temperature values in a. manner wellknown in the .art. The mercunf switch 55 is so Iplaced and the usual stop mechanism associated 12herewith in such manner that the mercury jsfoialenswhenthe temperature of the gases in the 'cic xnin'onstack 45 lowers a1; least a predetermined .afi'mlint The switch 55 will be hereinafter refer:e d to as the Stack switch.

An oil supply pipe 60 is oonnected to the In1et of valve I6 by means of a pipe 6I and Is likewise connected to the inlet of valve 33 by a pipe 62. Ignition means fozthe burner I3 is herein shown as comprising a by-pass pipe 63 having a needle valve 64, therein, the by-pass pipe being connected to pipes 6I and I5 so as to s hunt valve I6 and the needle va1ve 64 being so adjusted that there is always a relatively small flow of oil to the combustion pot I4 whereby a small pilot flame is maintained at all times. In a similar man ner, a by,-pass pipe 65 which is p'rovided with a needle valve 66 connects pipes 62 and 32 whereby a small supply of oilis constantly fed to combustlon pot 3I 0f water heater 30 so as I:o maintain a small pilot flame at all times. II: is to be understood that this oil pilot type of ignltion means has been shown herein as merely exemplary of one type of ignition means and that any of the other wellknown types of ignition means could be utillzed if desired.

The control system includes a room thermstat which is herein diagrammatically indicated as comprising a. mercury switch 68 which closed a circuit when the temperature of the room or space to be heated falls to some predetermined minimum, say '70 F. The control mechanism also includes a relay generally indicated at 69 which relay comprises a relay coil I0, an armature II, a switch arm I2, and a. coope'rating contact I3. The arrangement is such that upon energlzation ofrelay 0011 I0 the armature II is attracted and moves switch arm 12 into engagement with conta.ct I3 and upon deenergization of relay coil I0, armature II moves to the positi0n shown In the drawings under the influence cf gravity whereby switch arm I2 is movedaway from coutact I3. A slmllar relay generally indicated at. 14 is also included in I;he control system and comprises a relay coil I5, an armature I6, a switch arm II controlled thereby, and a cooperating oontact I8. In this particularembodiment of the invention, the control system is also sho'wn as including a manual switching mechanism I9 which indudes a. manually operable switch am 80 which normally engages a contact button III but may be moved into engagement with a couta.ct button 82. Power is supplied by line wires 83 a.nd 84 which may include the usual manually operated line switch 85.

Operation With the parts in the position shown, the space or room temperature is above the desired polnt; inasmuch as room therm0stat switch 68 Is shown in its open position and the water temperature 35 is at or above the desired point inasmuoh as mercury switch 43 is also in open position. Oil valves I6 and 33 are therefore both clos'ed am] the furnace I0 and water heater 30 are inoperative except for the hereinbefore mentioned small pilot flame which is herein shown for the purpose cf ignition. The temperatur6 of the gases in the stack 45 has dropped since the last operation o1. either of the heaters with the result that stack switch 55 is in open position. Likewise, the temperature of the air in air heating chamber I2 has dropped considerably since the last operation of the furnace I0 so that high limit swit'ch 26 is closed and fan switch 21 is open. Fan motor 20 and draft motor 49 are both inoperative and relay coils and I5 are deenergized.

The temperature of I;he room dr space t;o ba heated will, after a. period, drop below the desired value whereupon room thermostat switch 08 will niove 130 closed circuit position. =Movement cf room thermostat switch 68 to closed circuit positlon establishes a circuit for.oil valve I6, a circuit for relay coil I and conditions a. circuit for fan motor 20. The oil valve circult ls as follows: line 83, wire 80, room thermostat switch 68, wire 9I, high limit switch 26, wire 92, wire 93, oil valve I6, wire 94, wire 95, and wire 96 to line 84. The energizing circuit f0r relay 10 is as follows: line 83, wire 80, room thermostat switch 68, wire 9I, high limit switch 26, wire 92, wire 91, relay coil I0, and wire 98 to line 84. Energization of relay coil I0 moves switch arm I2 into engagement with conta.ct 13 to establish the following draft motor circu it: line 83, wire 99, contact I3, switch arm I2, wire IOI, wire I02, wlre I03, draft moto'r 48, and wlre I04 to line 84.

Energizatlon of oil valve I6 opens the same whereupon a full flow of oil is fed from oil supply pipe 60 through pipe 6I, oil valve I6, and pipe I t o combustion pot I4. This full flow of oil is ignited by the sn'1all pilot flame already burning in the combust ion pot I4 Whereupon the furnace I0 ls placed in condition to heat the air in air heating chamber I2. Energization of draft m0- tor 49 operates draft fan 48 130 create a. draft in the common stack 45 whereby a draft through furnace I0 and water heater 30 is created. Initial operation of furnace I0 creates an-increase in I:he temperature of the gases passing through ccmmon stack 45 with the result that stack switch 55 quickly moves to closed circuit position to establish a maintaining circuit for draft motor 49 as follows: line 83, Wire I08, stack switch 55, wire I09, wire I02, wire I03, draft motor 49 and wire I04 to line 84.

After the furnace I0 has been in operation for a short tlme, the air in air heatlng chamber I2 will become heated sufficiently'to cause thermostatic element 24 150 close fan switch 21 Whereupon fan motor 20 ls energized by the following circuit: line 83, wire 90, room thermostat switch 68, wire 9I, fan switch 21, wire I05, contact button 8I, manually operable switch arm 80, wire I06, fan motor 20, wire I0'I, nd wire 96 to line 84. Operation of fan motor 20 drlves fan I I whereupon air is circulated through air heating chamber I2 and headers I8 to the rooms or space to be heated.

As long a.s the room temperature remains below the desired point, oil valve I6 Will remaln open un1ess the temperature of the hea.ted air in the air heating chamber I2 rises above the setting of limlt switch 26 whereupon the llmit switch 26 will move to open circuil; position and deenergize oil valve I6 until such time as the temperature of the a.lr in air chamber I2 decreases to 1:0 a point below the setting of the' limit switch 26. Opening 01 hlgh limit switch 26 also deenergizes relay coil whereupon the initial energizing circuit f or draft motor 49 ls opened but the draft; motor 49 will continue in operation for at least a short time until the temperature 0f the stack gases fallssufiiciently to open stack switch 55. Likewise, fan motor 20 will continue in operatlon as long as room thermostat switch 68 is clased unless the temperature 013 the air in a.ir chamber I2 falls blow the setting of the fan switch 21.

Wh en the room temperature has been restored room thermostat switch 68 opens, oil valve I6' lay;coil I0, a.nd fan m0tor 20 will all be deen zed.-l A s abdve pointed out however, draft r'nofoi 49 will be maintained en'erg-ized by stack 'swlt'ch 55 for a shc rt period until the temperature of the gases passing through common stack 45 has dropped at least; a predetermined amount. 'I'his delayed deenergization of draftmotor 49 is provided for the usual purpose of furnishing combustion supporting air to combustion pot I4 for a short period after closure of valve I6 whereby the relatively la.rge amount of oil present in combustion pot I4 at the time oil valve I6 closes is supplie d witl sufilcient combustion supporting alt to provide proper smokeless combustion. By the time draft motor 49 is deenergized as the result of opening of stack switch 55, the quantity of oil in combustion pot I4 will have been reduced to the amount of oil permitted to flow through needle valve 64 in by-"pass pipe 63. Sufiicient air for sup'borting combustion of this sma.ll amount of oil is provided by the natural draft in the system.

In the similar manner, the temperature of the water in storage tank 35 will fall below the desired point whereupon mercury switch 43 Will be closed to establish energizing circuits for oil vlve 33 and relay coil I5. The circuit for oil valve 33 is as follows: line 83, wire IIO, switch 43, wire III, wire II2, oil valve 33, wire H3, wire 95, and wire 96 130 line 84. The energizing circuit for relay coil I5 is as folows: line 83, wire IIO, switch 43, wire lll wire H4, relay coil I5, and wire Il5 to line 84. Energization of oil valve 33 permlts a full flow of oil to combustion pot 3I ancl energization cf relaycoil 15 moves switch arm I'I into engagement with contact I8 1:0 establish the following energizing circuit for draft motor 49: line 83, wire H6, contact I6, switch arm 'II, w1're II'I, Wire I03 draft motor 49 and wire I04 to line 84. Operation of draft motor 49 produce s a. draft through common stack 45 and through furnace I0 and water heater as hereinbefore brought out. Combustion cf the large flow of oil to combustion pot 3I- first serves to raise the temperature of the stack gases whereupon stack switch 55 'closes 150 establish I:he above mentioned maintaining circuit for draft motor 49. This combustion 01 oil in combustion pot 3I also heats pipe coil 34 whereby the water in storage tank 35 ls heated until the temperature of the same returns to the desired point at which time switch 43 opens to deenergize 'oil valve 33 and relay coil I5. Deenergiaztion of relay coil 15 interrupts the initlal energizing circuit for draft motor 48 but; the maintaining circuit therefor will be maintained until the stack gas temperature has dropped at least a predetermined amount to open stack switch 55 whereby combustlon supporting air ls furnished combustion pot 3I until the excess oil therein has been consumed in the manner previously pointed out in connection with thecombustion of the oil in co-mbustlon pot I4.

Manually operable switch 19 may be utilized in order to operate fan motor 20 and fan I I for ventilating purposes by m0ving manually operable switch arm. 80 from contact button 8I and into engagement Wlth contact button 82 to complete an energizing circuit for fan motor 20 as follows: line 83, wlre II8, contact button 82, manually operable switch arm 80, wire I06, fan motor 20, wire I0I, and wire 96 t0 line 84.

From the fo regcing description, it will be noted that the present invention provides a simple improved cont'rol system by means of which the supply of combustion supporting air for a burner may be maintained for a. periud after thecessation of combustion. II: Will also be rloted that the invention provides a simple control system for a, plurality of burners which are herein shown as each burner is controlled in response to changes in difierent eonclitions. Spiacifically, one of the bu1ners is for the purpose of heating a dwelling er space and the other is for the purpose of supplylng hot water. The burnersare connected to a common stack ar'1d the invention utillzes a single draft controlling device, the arrangement being such tha.t when either burner is operated a supply of combustion supporting air is furnished thereto and this supplyof Combustion supporting air is maintained by means of a, single device responsive to the temperature of the gases passing through the common stack for a timed period after closure of the last to close of the valves-to wit, for a timed period after cessatyion v of combustion at the burner last to be shut down.

It is t be understood that any of the usual safety devices may be provided inconnection with the two burners for preventing operation thereof in the event the pilot flame falls or combustion fails to be established.

A specific embodiment of the invention has been herein shown and described but lt will be apprecialted that many changes and modifica;- tions can be made by those skilled in the a1t and I am therefore t'o be limited only in the purview of the appendecl claims.

I claim:

1. In combination, a pair of heetters each having a burner and a fuel supplying means therefor, a stack common to said two heaters, an eleotrical draft producing means operative to produce a draft throu'gh said common stack and heaters when energized an electrically 0p'erated fuel.sup ply valve in each of said fuel supplying means, t"1ermostatic means responsive to temperature conditions produced by said heaters, energizing circults operative to energize said fuel valves to open the same and- 1:0 energize said draft producing means controlled by said thermostatic means, switching means responsive to the temperature of the gases passing through said common stack and including a switch which closes after combustion is obtained in elther of said heaters and opens when the temperature of'the gases passing A through the common stack falls a predetermined amount alter cessation of combustion in both of said heaters, and a circuit operative to maintain operation of said draft producing means comtrolled only hy said switching means.

2. In cornbination, a pair of heaters each havlng a burner and a fuel feeding means therefor a common stack Ior said two heaters, a draft fan for prbducing a draft through said common stack, an electrie motor for drlving said fan, an electrical fuel valve in each of said fuel feeding means which opens when energized and closes when dee"fierglzed a thermostatic switch responslve to a temperatur'e}- condition produced by one of said heaters andwhich closes when the value of said conditlon decreases to a predetermined value, a relay, a clrcult for said relay and. one of said fuel valves Controlled by said thermostatic switch; a v

second thermostatic switch, parallel energizing clrcults 1'0r said draft fan motor controlled by said relays a switch responsive to the temperature of the gases passlng through said common Stack whlch closes alter combustion is obtained and which opens when the Stack gas temperature falls a. predetermlned. amount after oessation of combustion, and a third circultfor said draft fan motor controlled only by said stack gas temperature responsive switch.

3. In combination; a. heater for heating a. space arid having a burner and a. fuel supplying means therefor; a water heater havlng a burner and a fuel supplylng means therefor; a. common stack f0r said two heaters; a. draft controlling device in control of the draft through said common stack; a space heater fuel supply valve; a water heate't fuel supply valve; a space temperature responslve thermostat; connections between said space temperature responsive thermostat, space heater fuel supplyvalve, and draft controllirlg device operative to open said valve and to operate said device when the space temperature falls to a predetermined minimum; a water temperature responsive thermostat; connections between said walzer'temperature responsive thermostat, water heater fuel supply valve and draft controlling device operative to open said valve and to operate said device when the water temperature falls to a predetermined minimurn; and. a Single device operative to maintain operation of said draft con: trolling device for a time period after closure of the last to close of said fuel supply valves.

4. In combinatlon; a. heater for a space to' be' heated having a burner and fuel feeding means therefor; a water heater having a burner and. fuel feeding means therefor; 9. common stank for said two heaters; an electrlcally Operated draft riroducing device which creat9s a draft through said common stack when energized; an electrically operatecl fuel valve in each of said fuel feedlng means; a, space temperature responsive thermostatic switch; circuit connectlons between said switch, space heater fuel valve, and draft producing device operative to open said valve and energlze said device when the space temperature falls to a predetermined minimum; a water temperature responslve thermostatlc switch; electrlcal connections between said water temperature responslve thermostatic switch, water heater fuel valve, and draft producing device operative to each of said burners, control means operative to selectively open-said valves, a single ineans in control of the dratt for all of said. burners counections associated Wlth said control niearis and valves arranged to operate said draft controlling means to increase the drait to all of said burners upon the opening of any one of said valves by the control means, a slngle stank for all of said burners, a single device res'ponsive to the temperature of eombustion in said stack produced by operation of any of said burners, and connections betvireen said device and draft controlllng means arranged to operate the latter to c ontinue the increased draft to all of said burners, until the temperature of combustion in said stack has decreased at least a predetermlned amount as a Cil result 0f cessation of operatlon 01 all 01 sa1d burners.

6. In comblnatlon, a plurality of hea.ting de'vices each including a. burner, a, separate fuel supply controlllng vallve controlling the supplying cf fue1 to each of said burners, a. thermostat responsive to a. heat condition produced by one of said burners operative to bpen 1ts fuel supply valve when said heat condition reaches a, predetermined minimum, a thermostat responsive to a heat candltion produced by another of said burners operative to open its fuel supply valve when seid lastmentioned hea.t condition decreases to a predetermined minimum, means 111 control of the draft for all of sa.id burners, connections between said thermostats and draft controlling means operative to increase the draufi; to all of said burners when fuel is supplied to any one of said burners, a. common stack for all 013 seid heating devices, a single device responsive to the temperature of combustion in sald stack, and connections' between said device and draft; controlllng means operative to maintain such increased dratt to all of said bumers until the temperature of combustion has decreased at least a predeterm.lned amount upon cessation of combustlon ab all o1 said burners.

7. In combination, a, plurality of heating devices each having a burner and a. fuel supply therei'or, a. separate fuel valve in control of the flow o! Iuel to ea.ch of said burners, a singlemeans in control of the draft fdr all of sa.id burners, control mea.ns, means including connections between sa1d control means and valves and seid single draft control means operative selectively 170 open seid valves and to operaixa said draft controlling means upon the opening 1 any one of seid. valves, and a. Single device operative t;o maintain operation of said draft controlling means for a, periofl after closure of the last to;closeof saig1 fue1 valves.

JOHN P. KRIECHBAUM.

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