US3763849A

US3763849A - Combined space heater and water heater

Info

Publication number: US3763849A
Application number: US00233605A
Authority: US
Inventors: R Pfluger; Graw J Mc
Original assignee: Atwood Vacuum Machine Co
Current assignee: AVM ACQUISITION Co A CORP OF; Atwood Industries Inc
Priority date: 1972-03-10
Filing date: 1972-03-10
Publication date: 1973-10-09
Anticipated expiration: 1990-10-09
Also published as: CA946242A; GB1399563A; DE2310578A1

Abstract

A space heater and a water heater are combined in a single heating unit with each heater including a combustion chamber with a gas burner which is operable independently of the other gas burner. Together, the two burners control the flow of fresh combustion air into the chambers and the flow of the hot gases of combustion through the heaters.

Description

United States Patent [1 1 Pfluger et a1.

[4 1 Oct. 9, 1973 COMBINED SPACE HEATER AND WATER HEATER [75 Inventors: Richard T. PflugergJohn G.

McGraw, both of Rockford, Ill.

[73] Assignee: Atwood Vacuum Machine Company, Rockford, Ill.

[22] Filed: Mar. 10, 1972 [21] App]. No.: 233,605

[52] US. C1 126/101, 237/19, 431/193 [51] Int. Cl. F24d 9/00 [58] Field of Search 126/101, 85 B;

[56] References Cited UNITED STATES PATENTS 2,277,201 3/1942 Belt 126/101 3,280,885 10/1966 Kind] 431/193 2,078,576 4/1937 Laghetto... 431/193 3,693,874 9/1972 Fox 236/15 A Primary Examiner-William E. Wayner Assistant Examiner-William E. Tapolcai, Jr. Attorney-Wolfe, Hubbard, Leydig, Voit & Osann 5 7 ABSTRACT A space heater and a water heater are combined in a single heating unit with each heater including a combustion chamber with a gas burner which is operable independently of the other gas burner. Together, the two burners control the flow of fresh combustion air into the chambers and the flow of the hot gases of combustion through the heaters.

7 Claims, 7 Drawing Figures COMBINED sPAcE HEATER AND wATER HEATER BACKGROUND OF THE INVENTION The present invention relates to gas heating units and, more particularly, to the type of heating unit which selectively serves both as a space heater and a water heater.

SUMMARY OF THE INVENTION The primary object of the present invention is to provide a new and improved heating unit of the above described character which is more compact and safer for use in small mobile homes, camper trailers and the like than previous ,units of-thesame general character.

Another object is to control the flow of air through the space heater and water heater portions of the heating unit without the use of valves to simplify the unit and make it more compact. A related object is to use the burners of the space and water heaters in .a novel manner to act as valves to control selectively the amount of fresh intake air flowing through the space heater and the water heater. A more detailed object is to achieve the foregoing by taking advantage of the combined effects of aspiration and convection caused by the burning of gas at the burners.

Invention also resides in the novel construction and arrangement of parts of the heating unit to perform dual functions and the use of a single safety valve system for controlling the flow of gas to the burners.

These and other objects and advantages of the present invention will become readily apparent from the following detailed description when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded perspective view of a heating heating unit.

FIG. 7 is an enlarged cross-sectional view taken substantially along line 7-7 of FIG. 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT As shown in the drawings for purposes of illustration, the present invention is embodied in a compact heating unit 10 which includes both a space heater 11 and a water heater 13. The unit is useful particularly in camper trailers, small house trailers and the like to conserve space. Because of its compactness, the unit may be positioned out-of-the-way within the trailer such as within a cabinet 14 or other enclosure which is mounted along an outside wall 15 of the trailer.

Herein, the space heater 1! is mounted within the front wall 16 of the cabinet through an opening 17 and faces into the room containing the air to be heated. The

water heater I3 is located adjacent the space heater and includes a small hot water tank 19 (see FIG. 7) which is connected through suitable piping with hot water taps (not shown) disposed within the trailer. Gas burners 20 and 21 (see FIGS. 5 and 7) for the space heater and water heater, respectively, are mounted within passageways or

combustion chambers

23 and 28 within the twoheaters for burning gas supplied from a source (not shown) to operate the heaters. In operation, fresh combustion air is drawn into the two combustion chambers for use in the burning of the gas. After the gas is burned, the hot by-products of combustion rise through the combustion chambers thereby heating the air in the trailer and the water in the tank.

In accordance with the primary aspect of the present invention, the burners 20 and 21 are used in a novel manner to act as valves selectively controlling the flow of fresh combustion air through the space heater 1] and the water heater 13. This is achieved by taking advantage of the combined effects of aspiration and convection resulting from the operation of the two burners so that the fresh combustion air is drawn to each burner in proportion to the amount of gas being burned at each burner. For example, if the water heater burner 2l-is burning less gas than the space heater burner 20, the combined drawing effects of aspiration and convection resulting from the operation of the water heater burner is less than the combined effects of aspiration and convection resulting from the operation of the space heater burner. Consequently, a large portion of the flow of combustion air is drawn to the space heater burner than the portion of combustion air that is drawn to the water heater burner. Should the water heater burner be turned off, then substantially all of the combustion air flow would be drawn to the space heater burner. Similarly, if only the water heater burner were on, substantially the entire flow of air would be drawn to that burner.

So that the heating unit 10 operates in the above described manner, the unit is constructed with both the

combustion chambers

23 and 28 in communication with the flow of fresh combustion air into the unit and the burners 20 and 21 are positioned in their respective chambers to direct their by-products of combustion only through the passageways formed by their respective chambers. With this arrangement, the need for separate air intakes for each burner is eliminated as well as any mechanical valves and the like previously required to control the flow of air to the burners. Thus, the heating unit is not only simpler in construction but is more compact to conserve space within the trailer.

In the present instance, the space heater 1] comprises the front portion of the heating unit 10 and includes a generally rectangular casing 24 with an open front 25, a back wall 26, side panels 27 and top and bottom panels 29. A generally rectangular housing 30 is mounted within the casing on the inner surface of the back wall 26 and defines the combustion chamber 23 for the space heater. The side walls 31 of the housing are spaced from the

casing panels

27 and 29 and, along with a front wall 33, are heated by the by-products of combustion from the burner 20. The air in the trailer is then heated by the radiation of heat from the hot walls of the housing and by convection.

To supply fresh combustion air for burning the gas at the space heater burner 20, an intake duct 34 (FIGS. 3 and 7) connected to the back wall 26 of the housing communicates with the combustion chamber 23 through an inlet 35 (FIG. formed adjacent the lower end thereof and with the air outside the trailer through an opening 36 in the wall of the trailer. More particularly, the duct includes a generally rectangular portion 37 mounted vertically lengthwise on the outer surface of the back wall and an oval-shaped pipe 39 connected to the upper end of the rectangular duct and extending rearwardly therefrom away from the back wall. The rectangular duct thus defines a vertical passage 40 whose lower end opens into the combustion chamber 23 through the inlet 35. The upper end of the passage opens into the pipe 39 which is telescoped with a pipe 400 extending into the trailer from a rectangular vent 41 mounted within the opening 36 in the wall of the trailer. Thus, the intake duct connects the combustion chamber 23 in communication with the fresh air outside the trailer.

The by-products of combustion within the chamber 23 are vented outside the trailer through an exhaust duct 43. The latter is mounted on the outer surface of the back wall 26 around an outlet 44 (see FIG. 5) formed through the back wall adjacent the upper end of the chamber. Herein, the exhaust duct extends horizontally through the intake pipe 39 to conserve space. Moreover, the exhaust duct is positioned just above the central axis of the pipe as shown in FIG. 7 and extends slightly past the end of the pipe for connection with the vent 41. More particularly, the end of the exhaust duct telescopes with the vent into a pipe 45 (FIG. I) extending horizontally through the larger pipe 400. This arrangement is of advantage not only because the intake and

exhaust ducts

34 and 43 communicate with the outside air through the same vent but also because the heating unit 10 is easier to install since the telescoping together of the exhaust duct 43 and the pipe 45 also serves to align the intake duct with the larger pipe 40a of the vent.

As shown in FIGS. 1 and 3, the water heater 13 is mounted directly behind the back wall 26 of the casing 24 and includes the water tank 19 enclosed by a heat reflective shield 46 and a layer of insulation 47 which is packed between the shield and the tank. Cold water enters the tank through a lower port 49 and hot water exits the tank through an upper port 50. The water in the tank is heated by the conduction of heat from a helical tube 51 (see FIGS. 4 and 7) and by convection. Herein, the helical tube defines the combustion chamber 28 of the water heater and is wound upwardly through the water tank to exit near the top of the tank. More particularly, the lower inlet end 53 of the tube contains the water heater burner 21 and is connected to the back wall 26 in communication with the combustion chamber 23 of the space heater 11 through an opening 54 located in the back wall adjacent the inlet 35 and below the space heater burner 20. Advantageously, this arrangement permits the use of a common intake for delivering the fresh air required for the burning of gas by both the space heater and water heater burners and 21.

When the water heater burner 21 is in operation, the combustion air is drawn into the water heater combustion chamber 28 by passing through the intake duct 34 and the space heater combustion chamber 23. To exhaust the by-products of combustion from the water heater 13, the upper end portion of the helical tube 51 extends upwardly through the intake duct as shown in FIG. 3 and is connected to the exhaust duct 43 with an upper outlet 55 (FIG. 4) of the water heater combustion chamber communicating with the duct through an opening 56 in the side of the duct. Thus, the hot gases of combustion from the water heater are exhausted outside of the trailer through the same duct that the hot gases of combustion from the space heater 1] are exhausted.

As shown in FIGS. 4 and 7, the exhaust duct 43 includes a narrow inner end portion 57 which connects with the outlet 44 of the combustion chamber 23 and an integral tapered wall 59 connects the inner end of the exhaust duct with a larger outer end portion 60. The outlet of the water heater combustion chamber 28 opens into the outer end portion of the exhaust duct adjacent the tapered wall 59 which serves as a baffle to direct the flow of the hot combustion from the water heater out through the exhaust duct and to prevent such gases from flowing backwardly into the space heater combustion chamber.

When the heating unit 10 is being operated, fresh combustion air from outside is drawn into the intake duct 34 and flows through the horizontal pipe 39 and the vertical passage 40 and into the combustion chamber 23 by the operation of the space heater and water heater burners 20 and 21. Herein, aspiration resulting from the gas being expelled by the two burners and the draft resulting from the convection of the hot gases of combustion combined to produce a suction effect through the inlet 35 to draw the fresh combustion air from the outside in through the intake duct. After combustion air enters the space heater combustion chamber the flow of air is divided into two columns each taking a different path through the heating unit. One column of air flows upwardly through the space heater combustion chamber as a result of the combined effects of aspiration and convection produced by the operation of the space heater burner. Similarly, the other column of air is drawn upwardly into the water heater combustion chamber 28 by the combined effects of aspiration and convection resulting from the operation of the water heater burner 21. Thus, the air flowing into the space heater combustion chamber is divided between the space heater 11 and the water heater 13 with the aspiration and convection resulting from the operation of the two burners acting, in effect, as valves to divide the flow of air between the two burners.

The volume of fresh air flowing in either of the columns depends upon the amount of gas being burned at the burners 20 and 21 with the burner using the most gas drawing up a proportionally larger volume of air than the burner using a smaller amount of gas. If no gas is being burned at one of the burners, then only the operating burner acts to draw in fresh air.- In such case, the entire flow of air through the inlet 35 rises in a single column through the combustion chamber of the operating burner and substantially no air flows through the other combustion chamber. Thus, it will be apparent that, the two heaters 11 and 13 may be operated quite independently from each other and without a substantial flow of heat being lost from one heater to the other.

Advantageously, the burners 20 and 21 are located adjacent each other within the heating unit 10 thereby making it possible to use a single pilot burner 61 for igniting the gas from the burners. As shown in FIG. 5, the space heater burner 20 is mounted in the lower end of the chamber 23 above the inlet 35 andextends across the width of the chamber with one end supported by the side wall 31a of the housing 30. The other end of the burner is supported by a bracket 63 connected to the other side wall 31b of the housing. The lower end of the water heater burner 21 is supported by the bottom wall of the housing and extends diagonally therefrom to the inlet 53 of the combustion chamber 28.-The flame end of the burner 21 extends through the inlet 53 and into the helical tube 51 to direct the hot gases of combustion upwardly through the water heater combustion chamber to heat water in the tank 19.

As shown in HS. 4, the pilot burner 61 is positioned adjacent both the space heater burner and the water heater burner 21. Openings 64 and 65 (see HO. 6) in the two burners, respectively, allow gas from the burners to be ignited by the pilot burner. Thus, the pilot burner serves both the burners and thereby avoids the need of a separate pilot burner for each of the two burners.

Of additional advantage, the above described arrangement of the space and water heater burners 20 and 21 and the pilot burner 61 permits the use of a single safety system for controlling the flow of gas into the heating unit and to the burners. Herein, the gas source (not shown) supplies the gas for both the space heater 11 and the water heater 13 through a suitable conduit 66 (see FIG. 2) connected to the side panel 27 of the casing 24 and in communication with a main control valve 67. The latter may be moved by a dial 69 through three settings: closed, pilot and open. In the closed setting, gas is prevented from entering the heating unit. In

the pilot setting, gas may flow through a tube 70 to the pilot burner but gas is prevented from flowing to the other two burners 20 and 21. In the open setting, the valve acts to divide the main flow of gas between a space heater control valve 71 and a small conduit 72 leading to a water heater control valve 73 while still permitting a small amount of gas to flow to the pilot burner to keep it burning. To permit gas to flow from the space heater control valve and through a tube 74 leading to the space heater burner 20, the space heater control valve is movable automatically from a closed position to an open position in response to the temperature of the ambient air in the trailer as sensed by a temperature sensing device (not shown) well known in the art. In a similar manner, gas is permitted to flow through a tube 75 leading from the water heater control valve and to the water heater burner 21' as the water heater control valve is opened from a closed position in response to a second device (not-shown) for sensing the temperature of the water in the tank 19.

To ignite the pilot burner 61, the main control valve 67 is set at the pilot setting to allow gas to flow through the tube 70 to the pilot burner. The pilot burner may be lighted through an opening 76 in the front wall 33 of the housing 30. A door 77 normally closes the opening during the operation of the burners 20 and 21. Once the pilot burner is burning the main control valve 67 may be opened to allow gas to flow to the space heater and the water heater '

control valves

71 and 73 which are adjustable independently of each other to control the flow of gas to the burners 20 and 21 to regulate the operation of the space and the water heaters. To shut down the heating unit completely, the dial 69 only needs to be turned to the off position thereby closing the main control valve and stopping the flow of gas to both the heater burners 20 and 21 and the pilot burner 61.

We claim as our invention:

1. A combined space heater and water heater unit comprising a walled housing, a first combustion chamber defined by the walls of said housing and constituting a combustion chamber for the space heater, a first inlet located adjacent the lower end of said chamber, a first outlet located adjacent the upper end of said chamber, a water storage tank positioned adjacent said housing, means defining a second combustion chamber in heat exchange relation with said tank and constituting a combustion chamber for said water heater, a second inlet located adjacent the lower end of said second chamber and communicating with said first chamber adjacent the lower end thereof, a second outlet located adjacent the upper end of said second chamber, an intake duct communicating with said first chamber through said first inlet to supply fresh air to said first chamber, said intake duct communicating with said second chamber by way of said first chamber and said second inlet to supply fresh air to the second chamber, an exhaust duct communicating with both of said outlets to carry away hot gases of combustion vented from said chambers through said outlets, and first and second gas burners positioned adjacent the lower ends of said first and second chambers, respectively.

2. A combined space heater and water heater unit as defined in claim 1 further including means for supplying fuel gas selectively to each of said burners and for lighting the burners whereby the flow of fuel gas into each chamber and the hot gases of combustion rising upwardly therethrough cause fresh air to be drawn into such chamber substantially in proportion to the amount of fuel gas being consumed by the burner associated with the chamber.

3. A combined space heater and water heater unit as defined in claim 1 in which said intake duct and said exhaust duct are telescoped with one another.

4. A combined space heater and water heater unit as defined by claim 1 wherein said second inlet opens into said first chamber below said first burner.

5. A combined space heater and water heater unit as defined by claim 2 wherein said means includes a pilot burner operable to light both said first and said second gas burners.

6. A combined space heater and water heater unit as defined by claim 54 wherein said means further includes a main control valve communicating with a source of fuel gas and movable between a closed position to stop the flow of gas from the source, a pilot position and an open position, a space heater control valve selectively operable to permit gas to flow to the space heater burner, and a water heater control valve selectively operable to permit gas to flow to the water heater burner, said main control valve communicating only with said pilot burner when in said pilot position and with said pilot burner and both of said heater control valves when in said open position.

7. A combined space heater and water heater unit as defined by claim 1 wherein said exhaust duct is telescoped through a portion of said intake duct and includes a narrower inner end portion, a wider outer end portion and a tapered wall portion connecting said inner end portion to said outer end portion, said inner end portion connecting with said first chamber through said first outlet, and said second outlet opening into said wider end portion adjacent said tapered wall whereby the latter serves to keep the hot gases of combustion from the water heater from the flowing back through said inner end portion and into the combustion chamber of said space heater.

I UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,763, 849 Dated October s, 1973 Richard T. Pfl uger & John F. McGraw Inventofls) It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

The patentee McGraws name should read "-John F. McGraw-- instead of"'John G. McGraw" sighed and sealed'this 2nd dayof'Ju1y 19740 (SEAL) Attest: I v

EDWARD M. FLETCHER, JR. C MARSHALL DANN Attesting Officer I Commissioner of Patents FORM PO-1050 (10-69) uscoMM-oc scam-P69 I I i U.S. GOVfiRNMENT PRINTING OFFICE: I969 O356-33R

Claims

6. A combined space heater and water heater unit as defined by claim 4 wherein said means further includes a main control valve communicating with a source of fuel gas and movable between a closed position to stop the flow of gas from the source, a pilot position and an open position, a space heater control valve selectively operable to permit gas to flow to the space heater burner, and a water heater control valve selectively operable to permit gas to flow to the water heater burner, said main control valve communicating only with said pilot burner when in said pilot position and with said pilot burner and both of said heater control valves when in said open position.