US3601116A

US3601116A - Mobile home furnace with air circulator outlet means

Info

Publication number: US3601116A
Application number: US9264A
Authority: US
Inventors: Richard L Davis; James C Goodgion
Original assignee: Coleman Co Inc
Current assignee: Coleman Co Inc
Priority date: 1970-02-06
Filing date: 1970-02-06
Publication date: 1971-08-24
Anticipated expiration: 1988-08-24
Also published as: CA919537A

Abstract

A compact sealed combustion furnace adapted to be mounted within a closet or alcove of a mobile home is equipped with a downflow air circulator or blower characterized by auxiliary air outlet means oriented to direct the air discharged therefrom, first against one or more flue connection tubes, and then downwardly into the space between the combustion chamber casing and the rear wall of the exterior casing. The auxiliary air means may include passage-defining extensions on each side of the rear wall of the blower scroll, which are arranged to at least partially straddle the flue connection tube means. One or more slots can also be provided in the rear wall of the blower scroll in combination with or instead of the passage-defining extensions. In one preferred embodiment, a plurality of flue connection tubes are employed in combination with a plurality of transversely aligned slots in the rear wall of the blower scroll, the slots being oriented to direct air against and around the flue tubes.

Description

United States Patent 3,359,966 12/1967 Thomas l26/llOAA ABSTRACT: A compact sealed combustion furnace adapted to be mounted within a closet or alcove of a mobile home is equipped with a downflow air circulator or blower characterized by auxiliary air outlet means oriented to direct the air discharged therefrom, first against one or more flue connection tubes, and then downwardly into the space between the combustion chamber casing and the rear wall of the exterior casing. The auxiliary air means may include passage-defining extensions on each side of the rear wall of the blower scroll, which are arranged to at least partially straddle the flue connection tube means. One or more slots can also be provided in the rear wall of the blower scroll in combination with or instead of the passage-defining extensions. In one preferred embodiment, a plurality of flue connection tubes are employed in combination with a plurality of transversely aligned slots in the rear wall of the blower scroll, the slots being oriented to direct air against and around the flue tubes.

PATENTEU AUG24 Ian SHEET 1 OF 2 [NV/:N'MRS. 52 RICHARD L. DAVIS JAMES C. GOODGION swam/42x 7, gafimjdmug AT T'YS BACKGROUND AND SUMMARY Forced draft, downflow, sealed combustion furnaces for mobile homes are in widespread use in the United States. Usually, the exterior casing in its upper portion provides a blower compartment which receives a squirrel cage blower, having a bottom outlet directing air downwardly over a combustion chamber and radiator casing. The combustion chamber casing is spaced from the walls of the exterior casing to provide downflow air passages at the sides, rear, and front. The heated air is removed through a duct connected to the bottom of the exterior casing for supply to the room space of the mobile home. The air to the blower is primarily recirculated room air, but may also include makeup fresh air from outside the mobile home. The circuit for the combustion air intake and the flue gas exhaust is hermetically sealed from the circuit of the air to be heated. The combustion air can be taken in from beneath the floor and supplied to the burner through a sealed duct; or a concentric-type roof jack can be used, the combustion air being admitted through an annular space around the flue and passed downwardly through a sealed duct to the burner.

With such downflow mobile home furnaces, design problems are encountered because of the desire to obtain maximum heating efficiency while minimizing manufacturing costs. These design problems are further complicated by the necessity of limiting the exterior dimensions of the furnaces, which must fit into small closet or alcove spaces of mobile homes. Where the air circulator or blower is located above the combustion chamber casing, it is necessary to provide flue extension or connection tubes from the top of the combustion chamber casing to the flue. Since the flue connection tubes, which may be in the form of a single pipe or of a plurality of pipes, must extend through the blower compartment, they may cause objectionable heating of the interior of the blower compartment. While some preheating of the air supplied to the blower is desirable, excessive heating of the blower compartment can cause overheating of the door side of the furnace, which will usually include air filter elements, that must be kept below a certain maximum temperature. It is common to equip such furnaces with thermoswitches which shut off the burner of the furnace before the air intake filters exceed a maximum temperature. A related design problemwhich must be considered is the need to maximize the heating efficiency. It is desirable to recover additional heat from the flue gases after they leave the combustion chamber, providing this can be accomplished without overheating the blower compartment.

Because of installation space limitations, the maximum permissible depth of the exterior heater casing may require a relatively narrow or constricted airflow passage between the rear wall of the combustion chamber casing and the rear wall of the heater. This space can be even more constricted where a combustion air intake duct is provided along the rear wall of the heater, as may be desirable when the combustion air is supplied from a concentric-type roof jack. Consequently, this is another design consideration which relates to the maximizing of furnace efficiency.

The foregoing problems are substantially overcome, and the desired advantages are obtained by the present invention. More specifically, the blower is provided with an auxiliary air outlet which directs the air discharged therefrom first against the flue connection tubes and then downwardly into the space between the combustion chamber casing and the rear wall of the exterior casing. The auxiliary air in one embodiment is directed around the base of the flue tube (or tubes), and in another embodiment the auxiliary air is directed against the flue tubes at a higher level. The higher level outlet has the advantage of providing a greater limitation on the air temperature within the blower compartment, and it also provides for a longer heat exchange contact between the auxiliary air and the flue tubes. However, the lower position auxiliary air outlet, as will subsequently be described in detail herein, not only removes additional heat from the flue gas, but also greatly increases the velocity and volume of airflow through the rear air heating space. Where needed, therefore, both the intermediate and lower level auxiliary air outlets can be employed together.

THE DRAWINGS The present invention is shown in illustrative embodiments in the accompanying drawings in which FIG. 1 is a sectional elevational view of a mobile home furnace incorporating the blower auxiliary air outlet means of the present invention in one of its embodiments;

FIG. 2 is an enlarged fragmentary sectional view illustrating the auxiliary air outlet means of the heater of FIG. 1;

FIG. 3 is an enlarged fragmentary sectional plan view taken on line 3-3 of FIG. 1;

FIG. 4 is a perspective view of the blower casing or scroll, showing the modified rear wall construction as employed in the embodiment of the preceding figures;

FIG. 5 is an enlarged fragmentary sectional elevational view, showing a modification of the auxiliary air outlet means;

FIG. 6 is a front elevational view of the heater of FIG. 5 il lustrating the relation of the auxiliary air outlet slots to the flue connection tubes; and

FIG. 7 is a perspective view of the blower casing or scroll of FIGS. 5 and 6.

DETAILED DESCRIPTION Looking first at FIG. 1, there is shown a mobile home furnace F, which is mounted on a floor or base B, and which is utilized with a through-the-floor makeup air intake chute C and a through-the-roof concentric flue jack J. The ceiling and walls providing the alcove or closet space of the mobile home are not shown, but it will be understood that they will be utilized.

In general, the furnace includes an exterior casing having a top wall 10, a rear an 11, sidewalls l2, and a front which is closed by a door assembly 13, providing louver panels and 13b. Lower panels 13a may include a filterelement G. Within the heater is a combustion chamber and radiator casing 14 having a top wall 14a and a rear wall 14b. A combustion air intake duct 15 extends downwardly along rear wall 11, being closed at its front by wall 16. A downflow passage 17 for the air to be heated is provided between the

walls

14b and 16 in the embodiment shown. However, it will be understood that if the combustion air is supplied from beneath the floor, the downflow air passage 17 will be provided between walls 14b and 11. The front downflow air passage is provided between the front of the combustion chamber 14 and the closure wall 17. At the sides, the downflow air passages are provided between the sidewalls of combustion chamber 14 and the walls 12 of the exterior casing. The top of the compartment enclosing the combustion chamber is provided by the inclined transversely extending wall 18. Above the wall 18 within the upper portion of the exterior casing is provided a compartment for receiving the air circulator or blower l9. Blower 19 is of the squirrel cage type having side air intakes 20 which extend through the outer casing or scroll 21. The blower 19 provides a rear wall 22 against which air is directed by the action of the squirrel cage, and a bottom outlet 23 which is positioned on wall 18 in line with an opening 18a therein. As shown in FIGS. l-3, the wall 18 extends to the wall 16 around the flue tube 34. To the rear of the flue tube, an extension of the wall 18 can be provided in the form of a filler or closure plate 35. In the base of the exterior casing there is provided a compartment 36 for optionally receiving an air cooling unit 37, which is positioned in the path of airflow to the distribution duct 38.

In the operation of the furnace, room air to be heated is drawn in through the upper louver panels 13a, passing through the vestibule space 39 to the blower intakes 20. Partition P separates the lower vestibule space V, which is ventilated by lower panel 13b. Makeup fresh air can also be supplied through the chute C passing upwardly within the closet space outwardly of the rear wall 11 and the sidewalls to an annular air intake 40 around the base of the flue jack J, the incoming makeup air flowing over and around the combustion air box 41 and the flue box 42, as it flows to the rearward sides of the blower intakes 20. The combined room air and makeup air is discharged from the blower through the bottom outlet 33, and flows downwardly over and around the combustion casing 14, including the rear space 17. The heated air then flows around the sides of the cross duct 43, and then through the compartment 36 to the distribution duct 38.

The combustion air is taken in through the annular passage 44 of the roof jack, is passed through the interior of the air box 41 to the duct 15, which communicates at its lower end with the cross duct 43. From duct 43, the air is supplied to the burner 46. Burner 46 is illustrated as a gas burner, but it will be understood that other types of burners can be utilized, including oil burners. The hot flue gases pass upwardly within the combustion chamber casing 14, and enter the flue connection tube 34. As shown, the tube 34 is connected to the upper rear portion of the combustion chamber casing 14, extends upwardly between casing rear wall 11 and the rear wall 22 of the blower casing to a point at which it connects with the flue box 42. At its forward end, the box 42 connects with the flue passage 47.

It will be understood that the cooling unit 37 can be operated alternatively to the burner 46, that is, when the burner 46 is not in operation, the blower 19 will still] direct air downwardly through the airflow passages around the casing 14 and into the compartment 36 for flow over the cooling coils of the cooling unit 37. Cooled air will thereby be delivered to the duct 38. While the use of a cooling unit is optional, the construction of the present invention has the advantage of increasing the overall velocity and volume of air delivered to the compartment 36, thereby the heating features of the present invention also cooperate to provide the desired airflow during the cooling cycle of the furnace unit.

The distinctive features of the present invention will now be described with respect to each of the three embodiments shown in the drawing; namely, the embodiment of FIGS. 1-4, the combination embodiment indicated by dotted lines in FIG. 4, and the alternate embodiment of FIGS. to 7.

As shown more clearly in FIGS. 2-4, the auxiliary air outlet means can be provided by shaping the rear wall 22 of the blower scroll 21 to provide passage-defining

extensions

48 and 49. As shown in FIG. 3, the

extensions

48 and 49 partially straddle the flue tube 34, and interiorly, respectively, provide the

auxiliary air passages

50 and 51 which directs air against and around the flue tube 34. In the embodiment of FIGS. 1-4, the flue connection means 34 comprises a single flattened flue pipe which extends between the

extensions

48 and 49. If desired, the front wall 34a of the flue tube can be curved to correspond with the curvature of the lower concave portion 220 of the scroll front wall, but preferably a clearance or space 52 is provided between the walls 22a and 340, as shown in FIG. 3. In this construction, the single flue tube 34 functions as a full-width heat saver. Air is directed against the front 34a of the flue tube through the regular blower outlet 34, and against the outer corners and sides of the flue tube by the auxiliary passages 50 and 51 (FIG. 3).

The blower [9 can be rcmovably mounted on the wall 18 by means of suitable mounting tabs 52, which as indicated in FIGS. 3 and 4, can be located at each of the lower four corners of the blower scroll 21.

In the alternate embodiment of FIG. 5 to 7, corresponding parts are given the same numbers except that the numbers are primed.

Instead of being shaped to provide the passage-defining

extensions

48 and 49, as described with respect to the embodiments of FIGS. 2-4, the rear wall 22' has its intermediate portion provided with air outlet slot means designated generally by the number 100. As indicated by the flow arrows in FIG. 5, part of the air flowing downwardly along the inside of wall 22 is diverted through the slot means 100, flowing outwardly at high velocity against and around the flue tube means 34', and then downwardly into the airflow space 17. As indicated in FIG. 6, the slot means can be provided in the form of a plurality of slots in generally transverse alignment across the rear wall of the scroll at a spaced distance above the bottom thereof. For example, as indicated in FIGS. 6 and 7, the slot means can comprise slots 100a, 1001) and 1000. It will be understood that the dotted lines of FIG. 6 merely indicate the relative positions of the slots, which are horizontally aligned at the level indicated in FIG. 5. While flue tube means 34' can comprise a single flue tube, as described with respect to the embodiments of FIGS. 1-4, a plurality of flue tubes is preferred. As shown in FIG. 6, flue tube means 34 can comprise the

separate flue tubes

34a, 34b and 340'. With this construction, it is desirable to arrange the slots 100a, 100k and 100:: to direct the auxiliary air against and around all of the flue tubes.

With the embodiment of FIGS. 5 to 7, the blower mounting wall 18 at its rear is provided with

upward extensions

18a and 18b, and the tiller or closure plate 35 is moved to a higher level, as shown in FIG. 5. Filler plate 35 can be designed to fit snugly around the

flue tubes

34a, 34b and 346. On each side of filler plate 35 there can be provided rearwardly extending wall portions 35a and 351), as indicated in FIG. 6. This construction provides a passage 101 surrounding the intermediate portions of the flue tubes 34 through which air can flow from the slot means 100. As indicated in FIG. 5, after flowing in heat exchange relation with the tubes 34', the auxiliary air flows downwardly into the passage 17' between the rear wall 14b of the combustion chamber casing and the wall 16'. As indicated, air also enters this space from the regular blower outlet opening 33. I

Looking now at FIG. 4, there is indicated in dotted lines a further modification of the blower scroll to provide combination auxiliary air outlet means; namely a slot means 200 in combination with the passage means 48 and 49. In other words, the blower 19 has its rear wall 22 modified to incorporate both the previously described passage defining extensions and the slot means. This combination construction can be most advantageously employed with the single flue tube configuration of FIGS. 1-4. Alternatively, however, the single flue tube 34 can be replaced by multiple flue tubes, such as two separate flue tubes, providing the tubes can be fitted into the space between

extensions

48 and 49.

With this combination, auxiliary air will be directed out of the slot means 200 below a filler plate, such as the plate 35' of FIG. 5, against the intermediate portion of the flue tube means, and will flow downwardly around the flue tube means. At the level of the passage-defining

extensions

48 and 49, additional auxiliary air will be directed against and around the flue tube means, the

passage extensions

48 and 49 being arranged to partially straddle the flue tube means, as previously described with respect to the single flue tube embodiment of FIGS. l-4. The combined auxiliary air streams will then be directed downwardly into the airflow space 17.

With thecombination embodiments of FIG. 4 as well as the embodiment of FIGS. 5 to 7, there is a further advantage in maintaining the blower compartment at a lower temperature than where the flue tubes extend through the compartment for a greater portion of their length. By maintaining the blower compartment at a lower temperature, heating of the air intake filters can be minimized. As is well known in the art, replaceable filter means can be mounted immediately inwardly of the louver openings for the room air, such as the louver panel 13a. As indicated in FIG. 1 and also in FIG. 5, the filters G are positioned so that the incoming air flows through the filters, as it enters the vestibule 39 or 39' on its way to the blower intakes 20.

We claim:

1. A compact sealed combustion furnace adapted to be mounted within a closet or alcove of a mobile home, said furnace having an exterior casing including top, rear and sidewalls, flue means extending through said top wall, combustion chamber providing casing means mounted within said exterior casing in spaced relation to said walls, the upper portion of said exterior casing above the top of said combustion chamber casing means providing a blower compartment, room air inlet means communicating with said blower compartment through the front of said exterior casing, flue connection tube means communicating with said combustion casing means and extending upwardly from the top rear portion thereof through the rearward portion of said blower companment, passage providing means extending between the upper portion of said flue tube and said flue means, a squirrel cage blower mounted in said blower compartment including a scroll casing having air intake means on its sides communicating with said blower compartment and a bottom air outlet for directing air over and around said combustion chamber casing, wherein the improvement comprises providing auxiliary air outlet means for said blower, said auxiliary air outlet means being associated with the rear wall of said blower and being oriented to direct the air discharged therefrom first against said flue tube means and then downwardly into the space between said combustion chamber casing means and the rear wall of said exterior casing.

2. The furnace of claim 1 in which said auxiliary air means includes shaping said scroll rear wall to provide passage defining extensions on each side thereof which at least partially straddle said flue tube means.

3. The furnace of claim 1 in which said auxiliary air means includes providing said scroll rear wall with at least one slot therethrough.

4. The furnace of claim 3 in which a plurality of said slots are provided in generally transverse alignment across said scroll rear wall at a spaced distance above the bottom thereof.

5. The furnace of claim 1 in which a plurality of said flue connection tubes are provided.

6. The furnace of claim 1 in which said auxiliary air means includes scroll passage defining extensions on each side of said scroll rear wall which at least partially straddle said flue tube means, and at least one slot through said rear wall at a spaced distance above said passage defining extensions.

7. The furnace of claim 6 in which said flue tube means comprises a plurality of flue connection tubes.

8. A compact sealed combustion furnace adapted to be mounted within a closet or alcove of a mobile home, said furnace having an exterior casing including top, rear and sidewalls, flue means extending through said top wall, combustion chamber providing casing means mounted within said exterior casing in spaced relation to said walls, the upper portion of said exterior casing above the top of said combustion chamber casing means providing a blower compartment, room air inlet means communicating with said blower compartment through the front of said exterior casing, a plurality of flue connection tubes communicating with said combustion casing means and extending upwardly from the top rear portion thereof through the rearward portion of said blower compartment, passage providing means extending between the upper portions of said flue tubes and said flue means, a squirrel cage blower mounted in said blower compartment including a scroll casing having air intake means on its sides communicating with said blower compartment and a bottom air outlet for directing air over and around said combustion chamber casing, wherein the improvement comprises providing auxiliary air outlet means for said blower, said auxiliary outlet means including at least one slot extending through the rear wall of said scroll at a distance above the bottom thereof, said slot being oriented to direct the air discharge therefrom towards flue tubes and then downwardly into the space between said combustion chamber casing means and the rear wall of said exterior casing.

9. The furnace of claim 8 in which a plurality of said slots are provided in generally transverse alignment across said scroll rear wall in opposing relation to said flue tubes for directing air against and around all of said flue tubes.

10. A compact sealed combustion furnace adapted to be mounted within a closet or alcove of a mobile home, said furnace having an exterior casing including top, rear and sidewalls, flue means extending through said top wall, combustion chamber providing casing means mounted within said exterior casing in spaced relation to said walls, the upper portion of said exterior casing above the top of said combustion chamber casing means providing a blower compartment, room air inlet means communicating with said blower compartment through the front of said exterior casing, a flue connection tube communicating with said combustion casing means and extending upwardly from the top rear portion thereof through the rearward portion of said blower compartment, passage providing means extending between the upper portion of said flue tube and said flue means, a squirrel cage blower mounted in said blower compartment including a scroll casing having air intake means on its sides communicating with said blower compartment and a bottom air outlet for directing air over and around said combustion chamber casing, wherein the improvement consists essentially of: said scroll casing providing a rear wall wider than said flue connection tube and being shaped to provide passage defining extensions on each side of said connection tube which at least partially straddle it, said passage extensions terminating above said combustion casing means with a portion of said connection tube therebelow and said extensions being oriented to direct the air discharged therefrom around the portion of said connection tube therebelow and downwardly into the space between said combustion chamber casing means and the rear wall of said exterior casing.

Claims

1. A compact sealed combustion furnace adapted to be mounted within a closet or alcove of a mobile home, said furnace having an exterior casing including top, rear and sidewalls, flue means extending through said top wall, combustion chamber providing casing means mounted within said exterior casing in spaced relation to said walls, the upper portion of said exterior casing above the top of said combustion chamber casing means providing a blower compartment, room air inlet means communicating with said blower compartment through the front of said exterior casing, flue connection tube means communicating with said combustion casing means and extending upwardly from the top rear portion thereof through the rearward portion of said blower compartment, passage providing means extending between the upper portion of said flue tube and said flue means, a squirrel cage blower mounted in said blower compartment including a scroll casing having air intake means on its sides communicating with said blower compartment and a bottom air outlet for directing air over and around said combustion chamber casing, wherein the improvement comprises providing auxiliary air outlet means for said blower, said auxiliary air outlet means being associated with the rear wall of said blower and being oriented to direct the air discharged therefrom first against said flue tube means and then downwardly into the space between said combustion chamber casing means and the rear wall of said exterior casing.