US3096754A

US3096754A - Furnace fireplace

Info

Publication number: US3096754A
Application number: US10805A
Authority: US
Inventors: Mildred L Solomon
Original assignee: Individual
Current assignee: Individual
Priority date: 1960-02-24
Filing date: 1960-02-24
Publication date: 1963-07-09
Anticipated expiration: 1980-07-09

Description

July 9, 1963 H. c. HOWREY FURNACE FIREPLACE 2 Sheets-Sheet 1 Filed Feb. 24. 1960 2 A: g T

A 8 B l w 9 37 INVENTOR. HAROLD C. HOWREY BYWM ATTORNEY July 9, 1963 H. c. HOWREY 3,09

FURNACE FIREPLACE Filed Feb. 24, 1960 2 Sheets-Sheet 2 INVENTOR. HAROLD C. HOWREY NW6 W ATTORNEY This invention relates generally to heating apparatus adapted to heat a single room or plurality of rooms in a building and more particularly to a prefabricated fireplace so constructed as to heat by radiation and convection and capable of utilizing either solid or liquid fuel. The

application is a continuation in part of application Serial Number 606,109 filed August 24, 1956, now abandoned.

Fireplaces in common use are usually constructed to operate independently of the heating equipment provided to maintain the rooms or buildings at comfortable temperatures. Generally, such fireplaces rely on radiation from the flame and walls to heat the rooms in which they are disposed. The resulting heat is intense immediately in front of the fireplace and falls rapidly away with distance so that at six or eight feet in front or to the sides of the fireplace very little warmth is obtained. Another disadvantage of the common fireplace is the lack of provision of adequate temperature regulating means so that the fuel bums either too fast or too slow. The damper when provided must be manually regulated, is frequently inaccessible for manual operation during the time a fire is burning, and permits inefficient loss of heat through the flue even when partially closed by reason of the smallness of the exhaust area it controls with consequent rapid draft and fast burning flame. Unless a second supply of fuel, wood or charcoal is maintained at all times, the fireplace cannot be operated since it cannot burn the primary heating fuel, oil. Because of these disadvantages, the average fireplace is more ornamental than utilitarian and in fact many owners, for these reasons, maintain a simulated fire in the fireplace and thus convert it to an entirely ornamental function.

The principal object of this invention is to construct a fireplace which will avoid the disadvantages enumerated above. This is accomplished by the provision of a fireplace which burns either solid or liquid fuel, which heats by convection as well as by radiation, which is equipped with thermostatically controlled regulating means, and which may be install-ed as a furnace to heat a plurality of rooms or an entire building.

Another object of the invention is to provide a combina ti-on fireplace and furnace with an enlarged damper and enlarged firebox exhaust pass-age into the chimney, which will reduce the velocity of the combustion products and allow a slower burning fire with consequent reduction of heat loss.

A further object of the invention is to structurally combine a fireplace and furnace in a prefabricated unit capable of use with air ducts in a building to provide a hot air circulating system capable of maintaining the entire building heated to a regulated temperature.

A still further object of the invention is to provide within a combination fireplace and furnace capable of burning solid and liquid fuel, a thermostatic unit having separate elements for regulation of the liquid and solid fuel fires and each being manually preset to maintain a selected temperature range.

Still another object of the invention is to provide in a liquid burning fireplace the means for properly feeding the liquid fuel, maintaining a proper and varying level of the liquid in the burner in accordance with variations in damper positions together with provisions for cutting off the supply of liquid when temperature or safety con- 3,096,754 Patented July 9, 1963 ditions so require including such times as a solid fuel is substituted;

The novel features that are considered characteristic of the invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and its method of operation, together with additional objects and advantages thereof, will best be understood from the following description of a specific embodiment when read in connection with the accompanying drawings wherein like reference characters indicate like parts through the several figures and in which:

FIGURE 1 is a perspective view of a prefabricated fireplace and furnace combination constructed in accordance with the invention, partially broken away for convenience of illustration;

FIGURE 2 is a reduced scale section taken along line 22 of FIGURE 1 and adding portions of a building to show the fireplace and furnace combination installed therein;

FIGURE 3 is a vertical central section taken along line 33 of FIGURE 1 and showing the oil burner;

FIGURE 4 is a fragmentary perspective view of the oil burner, looking toward its right end as removed from FIGURE 1 and showing the oil shut off control associated therewith;

FIGURE 4A is a fragmentary vertical section, taken midway the width of the fireplace and illustrating the central, upper air passages;

FIGURE 5 is a diagram in perspective of the damper, and thermostat control and oil regulator unit corresponding to FIGURE 1 but omitting structural features of the fireplace, furnace combination;

FIGURE 6 is a sectional view of the oil regulator unit taken vertically from front to rear thereof and toan en larged scale;

FIGURE 7 is an enlarged vertical section of the safety shut off valve of the oil burner;

FIGURE 8 is a side view of the thermostat control unit shown partially in vertical section;

FIGURE '9 is a section taken on line 9-9 of FIGURE 8, with parts broken away for convenience of illustration;

FIGURE 10 is an end sectional view of the oil burner control section of the thermostat unit, taken on line 1010 of FIGURE 8, parts being broken away to better illustrate internal features;

FIGURE 11 is an end sectional view, taken on line 1111 of FIGURE 8, looking in the direction of the arrows toward the hard fuel thermostat control housing and spring, with parts broken away, and

FIGURE 12 is an enlarged fragmentary section taken on line 1212 of FIGURE 9.

The illustrated combination fireplace and furnace comprises an outer box-like chamber or shell S. The shell S has side or end walls 2, a rear wall 3, a bottom wall 4, and a top wall 5. A fine opening 8 for passage of combustion products and a duct 9, comprising a warm air outlet, for passage of hot air open through the top wall 5. The bottom of the shell has an opening 10 through which air is introduced by way of an air duct 11. An auxiliary fresh air intake 39 is provided through the end wall 2 of the shell S and is opened and closed by the gate 40 in a manner to be later described. This air intake may lead from any suitable location, as from the outside of the building through a duct not here shown. An ash disposing opening 12 leads through the bottom wall 4 to an ash receiving chamber in the building wall. Ashes may be removed by opening the door 38 on the exterior of the building. A trap door 35 is located in the bottom wall 14 of the firebox and communicates with the ash opening 12 by way of the spout 36 which enters the ash receiving chamber or trap 37 adjacent the clean out door 38. The front faceof the shell S has a large opening 6 for passage of. radiated heat .to the .room in which the fireplace is located and a smaller opening 7 closed by a grill 34, preferably of the louver type which permits the grill-openings who opened, closed or partially closed The opening 7 and grill 34 permit convection currents of warmed air to passed from the combination fireplace and furnace into the room.

A firebox F is disposed within and spaced from all of the walls of casing S, except the front wall. The firebox comprises a bottom wall 14, a rear wall 15, side walls 16 and a flat top 17. The front'of thefirebox comprises an upper front partial wall or closure 18. This wall extends upwardly and connects with. a pair of discharge passageways O, each having an inclined portion 18A which extends upwardly andrearwardly into a relatively flat portion 18B terminating in theflue nozzle 19. The flue nozzle 19 enters into the'flue stack 20.

The flue nozzle 19 has a bottom wall 27 which is fixedly secured to the top wall.1'7 of the firebox F at 28, see FIGURE 2. This bottom wall is inclined downwardly towards the back of the chimney so as .to provide space for mortar 29 to be received to prevent moisture from getting on the bottomwall 27uand also to prevent such water as condenses in the stack from running over into the firebox. The inclined wall 27 also serves to turn back downdrafts-oc-curring in flue 8 to increase the efficiency of the apparatus as will be explained more fully hereinafter.

The two discharge passageways O, O are divided by. a channel 21. Each of these passageways has end walls 22' and 23 converging towards and joining the rear edge of the stack nozzle 19, as best illustrated in FIGURE 1. The passageways O, 0 form apair offireplace smoke outlets which join the flue nozzle 19 at its front and sides. This construction provides a relatively large smoke receiving area at the topv of the firebox which.

gradually tapers into the nozzle 19 and has a relatively large exhaust opening thereto. Furthermore, the

converging walls

22 and 23 establish a path for the updraft of air and are instrumental in directing smoke efiiciently up the flue. rises and is separated into two columns by the channel 21. Each column of smoke upon rising contacts the upper walls 18A as well as the converging

side walls

22 and 23 and is caused to roll forwardly and downwardly and turn into a spiral pattern which leads upwardly to the flue.

Such structure reduces the velocity of the air and smoke being drawn into the stack, -and minimizes the heat loss because of the slower moving draft without impeding the exhaust of a large volume of air, smoke and other combustion products.

Referring to FIGURES 2 and particularly, smoke control dampers D and D are fixedly mounted on the shaft 24 which is pivotally journaled at 25 transversely of the discharge passageways O. The dampers control the exhaust ports 26 between the firebox Fand the smoke outlets O. In FIGURE-2, one damper 24 is illustrated in full lines when fully closed and by dotted lines when fully opened.

The firebox F is reinforced and supported'in spaced relation to the shell S byv a plurality of bars 41 which are secured to the firebox inany desired manner, as by welding, and which do notrestrict the expansion and con traction movement developed within the firebox walls. The bottom wall 14.of the firebox F is supported above the bottom wall 4 of the shell S, providing a space 30 completely across and under the bottom of'the firebox F. The rear wall: of the firebox'is spaced from the rear wall3-of' the shell providing an air space 31 completely across and up to the top of the said firebox. An air space 32 is formed between the top wall 17 of the firebox andthe top wall 5 of the shell and extends toward both sides ofthe firebox at each side o-f'the flue nozzle 19 and discharge passageways O, O, as best illustrated in FIG- More specificaally smoke fromburning fuel;

URE 1. Referring to FIGURE 4A, an air space 33 exists between the top wall 17 of the firebox and the bottom wall 27 of the flue nozzle 19. This space joins with the channel 21 between discharge passageways 0. These various spaces around the firebox provide passageways for air to move in contact with the firebox walls and by convection, pass into the circulating ducts, as will be further explained hereinafter.

A preferred form of burner B is illustrated particularly in FIGURES l, 3, 4 and 5. The burner comprises an elongated boxlike unit 42 having an inner chamber 43 and an outer downwardly extending wall 44 formed integral with but spaced from the chamber. A pair of walls 46 are securely afiixed to the lower portions of walls 44 by any suitable means, such. as the screws 47. In this manner, a pair of air inlet manifolds 45 are formed between the

walls

44 and 46 which extend, along both sides of the burner B and have inlet passages extending below its bottom. A series of holes 43 admit air from the manifolds 45 intothe mixing chamber 49.

The mixing chamber 49'has an adjustable nozz-le N super-imposed thereabove and extending the full length of the burner. The nozzle is formed of a pair of oppositely disposed adjustable gates or grates 54) which are preferably in the form of plates and pivotally mounted on one of their edges within the sockets 51 formed on the upper edge of the unit 42. The opposite edges 52 of gates 50 are adapted :to be moved towards and away from one another by raising and lowering them in regards to the burner. The gates 50 have a series of spaced plates or segments 55 formed on their adjacent faces between which air and flames generated within the mixing chamber 49 can pass and exit through the elongatedopening between edges 52 of gates 50. Each plate '55 extendstoward a mating plate on the opposite gate and is provided with either a tooth 53 or a notch 54. Mating teeth and notches on opposite plates cooperate with each other so thatupon movement of the gates 50' to open-position, the gates will be retained in such adjusted position to provide an opening for exit of the flame.

The gates Stl may be opened or closed manual-1y by manipulation of-handles 56. The open position is shown in FIGURES 2, 3 and 4 while the closed position is illustrated in FIGURES 1 and 5. When the gates are closed, solid fuel will be used within the firebox, but when the gates are opened, a liquid, preferably oil, is used for fuel.

Referring to FIGURES 3, 5 and 6, fuel oil is delivered into the base of the burner B by means of the supply line 57. The fuel is vaporized in the mixing chamber 49 by heat radiated from the gates 50 land the flame. A pilot flame exists at the point 58, receiving its air for combus tion through the tube 59 from the air manifold 45. As long as this pilot light is on the safety unit 69 will allow oil to enter into the mixing chamber 49.

The oil safety unit 6th comprises a relatively heavy metallic cap 61, having a hollow tubular downward extension 62 forming part thereof and adapted to slide within the tubular nipple 63, extending upwardly from the bottom wall 64 of the mixing chamber 49'. The cap 61 controls the flow of fuel from the supply line 57 through the port 65 within the nipple 63, through the port 66 of the extension 62. A spring-67 holds the cap 61 in its up position as shown in FIGURE 7 when the pilot-flame 58 is off but when the pilot flame is on, heat delivered by the pilot against the cap 61 will reduce the tension of the spring 67 allowing the weight of the cap 61 to lower the extension 62 within nipple 63 so that the port 66 will register with the port 65 allowing fuel to flow therethrough into the mixing chamber 49. In the event the pilot flame goes out, the tension in the spring '67 will increase, raising the cap 60 so as to shut off the supply of oil going to the mixing chamber when the ports '65- and 66 move out of registry.

The flow of oil to the burner B is also controlled bythe oil regulating unit R. Referring to FIGURES 5 and 6, this unit comprises a float chamber 6 8 having a float valve 69 therein which is actuated by the float 70. As the float 70 raises, it will close 'valve 69' and shut off the flow of oil from the supply line 71 into the float chamber 68. Oil passes from chamber 68 into line 57 and thence to burner B, as previously described.

The operation of the float valve 69 is further controlled thermostatically and also by a separate manual means. The supply of oil to the unit R and hence to burner B may be completely shut off by a master shut off valve 72, in supply line 71. Valve 72 is actuated by movement of the burner gates 50 through the connecting rod 73. One end of rod 73 is connected to the crank of valve 72, FIG. 6 and the other end of rod 73 is connected to the crank 74 forming part of one of the gates 59 by way of the stub shaft 75, FIG. 4. When the gates 50 are in lowered position as shown in FIGURES l and 5, the valve 72 will be closed shutting off the supply of fuel oil but when the gates 50 are manually moved to the position shown in FIG-

URES

3 and 4, the valve 7-2 will be opened, admitting fuel oil to burner B.

The thermostatic control of regulating unit R is obtained through regulation of damper movements. A crank 105 is fixedly secured to the transverse shaft 24 of the dampers D and D and is adapted to operate the connecting rod 106. The lower end of this connecting rod is pivotally connected at 1W7 to the walking beam 1138 which operates the plunger 109. The lower end of the plunger 199 engages the float lever 11%, either forcing the said lever down or allowing it to rise, opening or closing the float valve 6-9. When the dampers D and D move to close, the connecting rod 106 is raised. This pivots the walking beam 198 so as to lower the plunger 109 closing down the float valve 69, which shuts off the supply of oil into the burners B by way of the supply line 57. When the dampers D and D tend to open, the connecting rod 196 is lowered, pivoting the walking beam 1128 so as to raise the plunger i199 permitting the float valve 69 to open adding more fuel to the burner B.

The thermostatic control mechanism is best illustrated in FIGURES 1, 5 and 8. The dampers D and D are opened and closed by the action of thermostat unit T. The opening may vary depending upon the setting of the thermostat unit. In the burning of hard fuel, the damper operates more fully opened than does the damper while burning fuel oil, therefore, a dual operating thermostat has been provided.

Thermostat unit T includes a casing 76 adapted to be located within the front portion of the firebox behind the front wall 18, FIGURE 2. Extending forwardly from the casing is a tubular housing 77, terminating in a dial 78. Dial 78 is located outside the firebox on the face 79 of the fireplace, preferably centrally located.

Journaled within the sleeve housing 77 is a sleeve 80 which is rotated by the lever 81, fixedly secured to its outer end. The inner end of the sleeve 80 has a crank 82 fixedly secured thereto at 33, see FIGURE 8. Connected to the crank 82 is a rod 84, which raises or lowers the gate 40 by way of the connecting rod 85 through the bell crank 86, as best shown in FIGURE 5. Thus, manual operation of lever 81 on the thermostat control unit T serves to vary the opening or close the gate 40' which, when open, admits auxiliary fresh air into the circulating air chamber surrounding the firebox B.

The thermostat unit T includes a sleeve 87 journaled within the sleeve 81 A knob 88 is fixedly secured to the outer end of sleeve 87 and bevel gear 89 is fixedly connected by any suitable means to the inner end of sleeve 87. The bevel gear 89 also forms part of the drum or housing 90. Extending outwardly from the drum 90 is a cam flange 91 having an offset portion 92 formed thereon. A thermostat spring 93, preferably of bimetal, has one of its ends secured to the drum 91) at 94. The other end of the spring 93 is secured at 97 to the hub 95 of lever 96. Lever 9-6 and its hub 95 rotate freely on the tubular shaft 98, which is journaled within the tubular shaft 87. Shaft 98 is fixedly secured to the manipulating knob 125.

A second drum 99 is fixedly secured to the end of shaft 98. Within this drum is a second thermostatic spring 100. One end of spring 160 is secured to the drum '99 while the other end is secured to shaft 101 which floats within the tubular shaft 98. A crank 102 is fixedly secured to shaft 101 and is connected to the dampers D and D by way of the connecting rod 103:. The outside face of drum 99 has a fixed stop 104 for arresting movement of lever 96. The drum is held in a manually selected position by the spring loaded 'ball 111, FIGURE 12, which registers with the depressions 112 formed within the flange 91. The ball 111 operates within a plunger 113 which is slidably mounted within the base 114 afiixed to the casing 76. A roller 115 is journaled to the arm 116 forming part of the plunger 113. This roller engages the cam flange 91 of the drum 99, pushing the same against the said spring loaded ball 111. When drum 90 is rotated to a position in which the oflset flange portion 92 is opposite roller 115, the plunger 113 together with roller 115 and the spring loaded

balls

111 and 123 will slide together in the base 114- and cause the ball 123 to engage one of the locking depressions 124 on drum 99.

The operation of the thermostat unit T, when the fireplace is using fuel oil, is rescribed as follows, particular reference being made to FIGURES 8 and 10 illustrating the thermostat unit parts as manually set for consumption of such fuel. The knob 88 is set by hand so that a certain predetermined tension, depending upon desired temperature range, is placed on the thermostat spring 93, the knob being turned clockwise. This turns sleeve 87, drum 90 and spring 93 clockwise, as viewed in FIG- URES 5 and 8, or counterclockwise in FIGURE 10. The lever 96 connected to one end of spring 93 is also moved in a counterclockwise direction, as viewed in FIG- URE 10, causing the said lever to bear against the stop 104 of the drum 99 and move said drum clockwise, as viewed in FIGURE 11. This places a tension on the thermostatic spring which rotates the floating shaft 101 clockwise, as viewed in FIGURE 5, raising the dampers D and D in the direction of the arrow, or to the position shown by dotted lines in FIGURE 2. The amount of clockwise rotation of the knob 88 will govern the amount that the dampers are opened.

As the

springs

93 and 100 are heated 'by combustion products of the burning oil, they will expand, causing the shaft 101 to turn counterclockwise, lowering the connecting rod 103 and the dampers toward the closing position of the said dampers. This reduces the draft and lowers the flame. When the thermostatic springs 93 and 1% cool, they will contract, revolving the shaft 101 clockwise rotating the lever 102 clockwise, raising the dampers D and D' against their weight toward open position thus increasing the draft and consequently increas ing the flame.

When the knob 88 is preset by hand, it controls the general average temperature to be maintained in the following manner. Referring to FIGURE 5, the shaft 87 revolves the bevel gear 89 therewith. The bevel gear 89 revolves the bevel gear 117 rotating the universal shaft 118, bevel gear 119, vertical shaft 120 which is raised or lowered by means of the threads 121 within the casing 68A of the float chamber 68. This causes the lower end 122 of the rod 120 to engage the lever of the float 70 holding the float valve 69 to a predetermined level of the float for opening, but will permit the said valve to close.

When hard fuels are to be burned, the gates 50 are closed by the levers 56. This will operate the connecting rod 73 leading to the shut ofi valve 72, completely shutting oif the oil supply to the regulator unit R. The knob 88 is then manually turned counterclockwise rotating the drum 90 counterclockwise until the offset por- 7 tion 2 of the flange 91 makes a partial revolution and engages the roller 115 and the ball 111, which forces the plunger 113 to the position shown in FIGURE 12. This movement causes the spring loaded 'ball 123 to engage one of the depressions 124 of the drum 99.

As the drum 90 is revolved counterclockwise, the lever 96 will leave its contact with the stop 104 of the drum 99, there being no further need of contacting the said stop with the am. In order to set the damper for hard fuel, the knob 12.5 is then rotated clockwise. This will rotate the tubular shaft 8, including the drum 99 clockwise tightening the thermostatic spring 1W. Tension in spring 100 rotates the floating shaft 181 clockwise, which will turn the crank 162 clockwise, raising the connecting rod 103, together with the dampers D and D opening the same to any desired position.

The spring loaded ball 123 will hold the drum 99 when the operator stops rotating the knob 125. As the fire increases due to the heated draft, the thermostatic spring 1% will be heated and expand so that the shaft fill will rotate counterclockwise together with the crank M2, lowering the dampers and tending to close them. In this manner, the dampers are first set for a desired tempera ture range and then are automatically moved toward closing when the flame and heat from the fire act on the thermostat unit to reduce the draft with resulting lowering of the flame. This in turn causes the thermostatic spring to contract moving the dampers to increase the draft. The flame is thus regulated in a restricted temperature range.

Therefore, as is apparent from the above, when the fireplace is burning liquid fuel, thermostat T, by operation of knob 88, combines both thermostat elements for the purpose of closely controlling the operation of the dampers D and D. That is, by the use of the extra long bimetallic strip, resulting from the combination of the two elements, the sensitivity of such elongated strip to variations in temperatures operates the dampers upon only a small change in temperature.

On the other hand, when solid fuel is being burned in the fireplace, such accurateness of damper control is not necessary or desirable. By the use of the single thermostat element 10%) damper control is less sensitive and such dampers operate through a greater degree of rotation.

The principal draft of the present fireplace furnace is through the front opening, although a side draft may if desired be provided through intake 39. Air duct 11 is a cold air return from rooms heated by the fireplace through duct 9.

The air to be heated by the firebox F enters by way of the duct 11 and opening 10, passing along the bottom wall 4 of the shell S. This warmed air travels up both sides of the shell around the firebox through the spaces 30, and around each side of the smoke outlets O, as indicated by the arrows in FIGURE 1. Warm air also moves between the smoke outlets through the channel 21 into the heat chamber 21A from where it moves by convection current through the grill 34 into the room in which the fireplace is situated, reaching all parts of said room. Some of the heated air moves upwardly through duct 9 to heat rooms other than the one in which the fireplace is located. It can readily be seen that the warmed air is efficiently heated by contact with large areas of the heated surface of the firebox.

By means of the present furnace, greater efliciency is achieved from a fireplace so that it can by radiation and convection operate to serve as a furnace. The structure is open at the front so that the charm of a fireplace is not lost and at the same time the arrangement is such that a forced draft is not necessary. It is of particular importance that the upper portion of the firebox is formed by the back wall 15, a top wall 17 extending at substantially right angles thereto, and a partial front wall 18. Wall 18 extends downwardly a distance suificient whereby the smoke circulating spirally in the upper chamber of the firebox, as explained hereinbefore, does not escape through the front opening of the fireplace. Impeding the smoke and the heated air velocity contributes in a great part to the invention in causing sulficient convection heating from a fireplace to heat other rooms.

By reason of the wall '27 at the lower end of flue 8, the downdrafts are not capable of blowing smoke into the room as such downdrafts are stopped or re-directed back up the flue.

Although a certain embodiment of the invention has been shown and described, it is obvious that many modifications thereof are possible. The invention, therefore, is not to'be restricted except insofar as is necessitated by the prior art and by the spirit of the appended claims.

What is claimed is:

1. In a fireplace, a single compartment, open-front firebox; a liquid fuel burner in said firebox which may be closed to permit the use of a hard fuel, said liquid fuel burner comprising an elongated chamber for holding and vaporizing the fuel, a pair of gates closing said chamber and movable to provide an elongated flame nozzle, means defining air inlets to said chamber, means defining a fuel inlet, an air inlet tube for a pilot flame, and valve means on said fuel inlet means for closing the fuel inlet means when said pilot flame is extinguished; a fuel line leading to said fuel inlet; a fuel regulating unit incorporated in said fuel line; a shut-off valve in said fuel regulating unit; and means connected between said liquid fuel burner and said shut-off valve for closing said valve upon closing said burner.

2. In a fireplace, a single compartment, open-front firebox, a liquid fuel burner in said firebox, a pivoted grate supported over said liquid fuel burner for rotation between an open liquid fuel burning position and a closed position for supporting hard fuel to be burned, a fuel line leading to said liquid fuel burner, a fuel regulating unit incorporated in said fuel line, a shut-off valve in said fuel regulating unit, connecting rod means connected between said pivoted grate and said shut-oif valve for shutting off said valve upon rotation of said grate to a hard fuel burning position, a thermostat, setting means connected to said thermostat for setting the latter, a pivotal damper connected to said thermostat and rotatable by the latter between open and closed positions, said fuel regulating unit being provided with a float valve adjustable between open and closed positions, and means connected between said setting means and said float valve to adjust said float valve between open and closed positions with the setting of said setting means as the latter sets said thermostats which control rotation of said dampers in similar movements of opening and closing as the float valve.

3. A fireplace comprising means for burning fuel in fluid form, means for burning fuel in solid form, damper means in said fireplace, a dual control thermostat unit having a pair of thermostatic elements, means for setting both of said thermostatic elements for operation together to preset said damper for movement which will achieve a desired temperature range when liquid fuel is burned, said pair of thermostatic elements when set as a unit providing a greater sensitivity in operation than when set singly, and means for disengaging one of said thermostatic elements for operation singly of the other of said thermostatic elements to preset said damper for movement which will achieve a desired temperature range when solid fuel is burned.

4. In a fireplace structure, a discharge passageway, a firebox having an exhaust port communicating with said discharge passageway, damper means pivotally mounted in said discharge passageway for rotation between open and closed positions, a grate in said firebox movable between a closed position for supporting solid fuel to be burned and an open position, liquid fuel burner means disposed below said grate for operation in the open position of the latter, first thermostat means connected to said 'damper means for controlling operation of the latter in the closed solid fuel burning position of said grate, and second thermostat means connected to said damper means operative through said first thermostat means for controlling operation of said damper means in the open liquid .fuel burning position of said grate, said first and second thermostat means being operaitve to rotate said damper means toward closed position as the temperature adjacent the fireplace increases and to rotate said damper means toward open position as the temperature adjacent the fireplace decreases.

5. In a fireplace structure, a discharge passageway, a grate movable between a closed position for supporting solid fuel to be burned and an open position, liquid fuel burner means disposed below said grate for operation in the open position of the latter, means defining an exhaust port communicating with said discharge passageway, pivoted dampers in said discharge passageway, and thermostat means connected to said dampers for controlling the operation of the latter, said thermostat means having dual operational functions rfor pivoting the dampers through different degrees of response for the two positions of the grate.

References Cited in the file of this patent UNITED STATES PATENTS 1,350,495 Hagenbuch Aug. 24, 1920 10 Johnson Feb. 17, 1925 De Florez May 5, 1925 Cesa Oct. 18, 1927 Jacobs Feb. 21, 1928 Walters Aug. 21, 1928 Claybaugh et al. Sept. 3, 1929 Lake July 8, 1930 Cage Mar. 1, 1938 Larson Oct. 1, 1940 Donley May 27, 1941 Breese Apr. 18, 1944 Howrey Oct. 31, 1950 Donley July 24, 1951 Snook Jan. 12, 1954 McCarty et a1 Oct. 4, 1955 Dupler May 29, 1956 Johnson June 12, 1956 Carpenter June 25, 1957 FOREIGN PATENTS Great Britain July 29, 1938 Canada Dec. 1, 1959