United States Patent 3863962

Small furnaces of the counterflow type, conventionally located in narrow closets or alcoves of mobile or modular homes, are readily installed by sliding on a sheet metal floor plate having a plenum connection to a sub-floor air duct. The floor plate has a central window surrounded by a raised bead portion. The bead portion has aft extending skid parts on which the furnace is slid. The similarly windowed base frame of the furnace has a downward flange which seals against the juncture of the base plate bead with a surrounding planar plate portion. The base frame has forward turned tabs which engage slots into the aft side of the aft lateral bead part of the floor plate. When they are engaged, the furnace can be secured by a pair of screws at its front end only.

Application Number:
Publication Date:
Filing Date:
Intertherm, Inc. (St. Louis, MO)
Primary Class:
Other Classes:
126/119, 285/24, 285/424
International Classes:
F24C15/08; (IPC1-7): F16L/; F16L37/26
Field of Search:
285/325,24,27,67,424 126
View Patent Images:
US Patent References:
3672706MOUNTING MEANS1972-06-27Chilcoat
3656782DUCT STRUCTURE1972-04-18Molino

Primary Examiner:
Arola, Dave W.
I claim

1. For installing counterflow furnaces and like air-delivery appliances connectable through a floor to a sub-floor air duct, a slide-on base-to-plenum assembly comprising

2. For facilitating removal of an air-delivery appliance as well as its installation,

3. A slide-on base-to-plenum assembly as defined in claim 1, wherein

4. A slide-on base-to-plenum assembly as defined in claim 1,


Furnaces conventionally utilized in mobile homes may be of the counterflow type, in which heated air is delivered downwardly through the mobile home floor to a sub-floor air duct, which extends to heating registers, the combustion air being exhausted upwardly. Return air may flow through the room space to inlets in the front door of the furnace cabinet. Similar installations may be made in other housing units such as modular homes. In such installations, space is at a premium; and it is conventional to install the furnace in a narrow alcove or closet. From a practical standpoint the only convenient access may be at the front of the furnace.

To conduct heated air from the bottom outlet of the furnace to the subfloor air duct a plenum connection must be made, which should be fairly well sealed. The problem of sealing has offered considerable difficulty. If a flexible seal member is put in place and an attempt made to push the furnace back into the narrow alcove or closet on top of the seal, there is danger of bending or damaging such a flexible seal. The problem is sufficiently serious that one well-known manufacturer of such furnaces provides a substantial space at the bottom surface of the furnace cabinet for access to make a connection from the furnace to the sub-floor duct. To provide such access space, however, results in raising the furnace to an undesirable height.


The objects of the present invention include:

Providing a slide-on metal-to-metal seal between the furnace air outlet and the plenum connection to a sub-floor air duct;

Providing secure engaging means for the aft portion of the furnace cabinet, so that final securement of the furnace may be by simple screws at its forward edge; and

Providing for easy removal of the furnace from such alcove or closet and for replacement therein. Other objects will be apparent from the detailed specification hereof.

Briefly summarizing the invention, an air seal is made between two rugged metal members; a sheet metal floor plate installed within the furnace alcove, and a rectangular base structure member for the furnace itself, which may likewise be drawn of sheet metal. The floor plate has a central window at which a plenum connection is made to the sub-floor air duct. A raised bead portion surrounds the window. Those bead portions which flank the window serve as aft extending skid parts, supporting the furnace as it is being skidded back into position within the alcove.

The frame member at the furnace base has a downward formed flange terminating in a planar lower edge which is substantially continuous and, in installed position, fits about the bead of the floor plate on its outer juncture with a planar portion of the floor plate, thus providing a nesting seal. Along the aft lower edge of the appliance base frame member are forward turned tabs, to engage in slots along the sloping aft edge of the floor plate bead. When the furnace is skidded backwards along those bead parts which flank the window, the forward turned tabs will pass over the slots at the aft side of the aft bead; then by moving the furnace slightly forward to final installed position, the tabs will engage within the slots and the downward formed flange of the furnace base will engage sealingly around the bead of the floor plate.

The preferred embodiment includes detailed features illustrated and described hereafter.


FIG. 1 is a perspective view of a slide-on base-to-plenum assembly embodying the present invention. A furnace to which the base frame member is attached is shown in phantom lines.

FIG. 2 is a plan view of the floor plate of the present invention, the cooperating base frame member being superimposed in the lower half of the drawing. The phantom lines show a typical position of the base frame while the furnace is being skidded into position.

FIG. 3 is an enlarged sectional view taken along line 3--3 of FIG. 2. The solid lines show the assembly in installed position. The phantom lines show the extreme aft (left) position of the base frame, preparatory to inserting its tabs into the slots of the base plate.

FIG. 4 is an enlarged sectional view taken along line 4--4 of FIG. 2. Its solid and phantom line showings correspond respectively to those of FIG. 3.

FIG. 5 is an enlarged sectional view taken along line 5--5 of FIG. 2, but showing the base frame in the phantom line position of FIG. 2.

FIG. 6 is an enlarged fragmentary view corresponding to FIG. 3 showing the parts when a furnace, shown in phantom, is tilted preparatory to removal.


In FIG. 1 there is shown schematically a flooring system b of the furnace closet or alcove of a mobile home or the like, in which air warmed by a furnace is to be delivered downward through a sub-floor duct d to a longitudinal delivery duct which supplies heat to floor registers, not shown. At the upper end of the duct d is a sheet metal plenum f which serves in effect as an adapter connecting the duct d to the floor plate, generally designated 10, of the present invention.

The end of the floor plate shown at the lower left of FIG. 1 is spoken of as its forward end, because it is presented at the front of the alcove or closet, at which the forward end of heating furnace is accessible. The remote end is referred to as the aft end.

The general construction of the floor plate 10 may be seen in FIGS. 1 and 2. It is formed preferably of galvanized sheet metal, drawn from a planar outer plate portion 11 to the flanged configuration shown. The floor plate 10 has on its aft side a raised aft flange 12, seen to the left of FIG. 2; its forward edge 13 is unflanged. Side spacing flange parts 14, 15 near the front and rear, respectively, of the plate 10 are spaced more widely than intermediate flange parts 16 between them; these serve to guide and center the appliance base frame member, hereinafter described. For these purposes of guiding and centering, the outer side edges of the planar portion 11 have entrant guide ridges 17 which commence somewhat aft of the forward edge 13 and lead in to the width between the intermediate flange parts 16. Portions 18 of the floor plate 10 outwardly of the ridges 17 are thus slightly raised. The same features are utilized inward of the aft flange parts 15; they are best seen in FIG. 5. The flanges 12, 14, 15 serve as spacers, establishing the minimum floor plan of a closet or alcove in which a furnace may be installed with necessary wall clearance.

Located substantially centrally within the floor plate 10 is a central window 20, large enough to offer minimum interruption of the flow of heated air to a range of sizes of plenums such as the plenum f. It is bounded by a margin 21 in the plane of the outer plate portion 11. To the window margin 21 the upper edge of the plenum f is sealedly connected prior to installing the furnace g, in a conventional manner, such as by bending metal tabs from the plenum against the margin 21.

Between the window margin 21 and the outer plate portion 11, the floor plate 10 has a raised bead portion, generally designated 23, which completely surrounds the window 20. The bead portion is formed upwardly by conventional forming techniques to the plane 24 in which lies the uppermost surface of the bead 23. The varying configuration of the bead 23 is best seen in FIG. 2. At the sides of the window 20 (shown above and below in FIG. 2) the bead portion 23 has skid parts 25 which flank the window 20, as best seen in FIG. 5, and extend from a point forwardly of it to an aft lateral bead part 26, seen in FIGS. 2 and 3. The aft lateral bead part 26 is considerably wider at its top plane 24 than the rounded window-flanking skid parts shown in FIG. 5. Widest, however, is the forward lateral bead portion 27, as seen in FIGS. 2 and 4.

The outer side of the entire bead portion 23 slopes downward to a line of juncture 28 with the planar outer portion 11, as seen for example in FIG. 4. This line of juncture is used for sealing, as hereinafter described.

Referring to FIG. 2, at the line of juncture 28 of the aft side of the aft bead part 26 are a pair of slots 30, blanked out of its entire aft surface and extending slightly forwardly into the planar plate portion 11 thereadjacnet. As seen in FIGS. 2, 3 and 6, the slots 30 remove, over their width, all the material in the sloping side of the aft bead part 26. Preferably the slots 30 are spaced not far inward from the skid parts 25. Except as interrupted by the slots 30, the outer edge of the raised bead portion 23 is continuous and slopes downwardly and outwardly to the line of juncture 28 at which it meets the outer planar portion 11.

The mating member of the present invention is an appliance base structure gnerally designated 33, built as a reinforcing frame into the otherwise conventional counterflow furnace whose rectangular cabinet is generally designated g, as illustrated fragmentarily in phantom lines in FIGS. 1, 5 and 6. While the cabinet g is spoken of herein as a counterflow furnace, it might instead by any appliance, such as an air conditioner or a combination air conditioner-furnace, designed to deliver air directly downward through a floor to a sub-floor duct.

The appliance base structure 33 is seen in perspective in FIG. 1 and the broken away lower half of FIG. 2; FIG. 5 shows it in aft elevation and the other figures include fragmentary sections thereof. Formed preferably of galvanized sheet metal, the base structure member 33 is essentially a normally horizontal substantially rectangular frame-like member whose central air-delivery window is demarked by a reinforcing flange 34 which rises from its planar upper surface 35. The surface 35 terminates in a continuous outer flange 36 formed downwardly at substantially 90° to a planar lower edge 37. Considered in plan view, the base structure member 33 is dimensioned to fit along its lower edge 37 at the juncture 28 at the outer edge of the floor plate bead 23. This provides a sufficient seal to the plenum f to deliver the warmed air from the furnace g under the pressure of its blower. For more secure sealing, outwardly turned air seal marginal portions 39 are provided along all four sides of the base structure 33, stopping short of its rounded corners. The lower surfaces of the seal margins 39 are co-planar with the lower edge 37; they rest against the outer plate portion 11; and to the extent that air might tend to escape beneath the lower edge 37, they provide a relatively long escape path whose resistance increases the efficiency of sealing.

The aft wall portion of the outer flange 36 of the base structure member 33 is slightly different, as herein set out, and is therefore referred to as the aft base flange 40. Centrally and over the greater part of its length it has an air seal marginal portion 41 turned outward. Flanking the ends of this marginal portion 41 are a pair of inward turned (that is, forward turned) tabs 42, whose undersurfaces also lie in the plane of the lower edge 37, as seen in FIGS. 3, 5 and 6. The length of the tabs 42, shown in FIG. 5, is slightly less than the length of the slots 30 of the floor plate as seen in FIG. 2. The tabs 42 interfit within the slots 30 when the appliance base structure is in installed position, as shown in FIGS. 2 and 3. In such installed position, the planar lower edge 37 will fit in the line of juncture 28 of the floor plate, as typically shown in FIG. 4.

The manner or use of the invention will now be described. The floor plate 10 is first secured to the floor system b within a heating closet or alcove, as by screws, and the connection of the plenum f to the central window 20 is sealedly made. Then the furnace g, assembled to include the reinforcing base structure member 33, is rested, with its aft base flange 40 first on the broad upper surface of the forward bead portion 27. The furnace g is positioned midway between the side flange parts 14, and pushed aft, guided by the ridges 17. After its aft base flange 40 passes the forward bead portion 27 it will be supported, as shown in FIG. 5, on the bead skid parts 25 which flank the central window 20. These narrow bead skid parts 25 facilitate the skidding of the base structure member 33 forwardly, elevated by them and guided by the air seal margins 39 between the intermediate flange parts 16 of the floor plate 10.

From the position shown in phantom lines in FIG. 2, which correspond with the cross-sectional view FIG. 5, the furnace cabinet g is pushed to an extreme aft position shown in phantom line in FIG. 3, wherein the aft air seal marginal portion 41 may abut the flange 14 which demarks the aft edge of the floor plate 10. In this position the tabs 42 will be immediately forward of the slots 30 in the aft lateral bead 26 of the floor plate; while the forward outer flange 36, seen in phantom lines in FIG. 4, will rest on the broad forward bead portion 27. The furnace is then pulled slightly forward (toward the heating closet entrance) to the installed position shown in solid lines FIGS. 3 and 4. This serves to engage the tabs 42 within the slots 30 and to fit the planar lower edge 37 of the furnace base member sealedly around the entire bead 23 along the line of juncture 28.

With the tabs 42 so engaged, securement of the furnace g to the floor system b is completed by using two screws (not shown), one through each clearance hole 44 through the upper surface 35 of the base structure member 33, to engage either the floor plate 10 or the floor system b in a conventional manner.

If it becomes necessary to remove the furnace g for servicing or replacement, such screw connections through the holes 44 are first removed. To disengage the tabs 42 from the slots 30, the furnace g is pushed aft. Thus, in FIG. 6 the furnace g has been pushed aft to the point that the aft air seal marginal portion 41 abuts the aft flange 12 of the floor plate 10. The furnace g is then tilted aft to raise the tabs 42 above the slots 30, and to the level 24 of the upper bead surface as shown. To aid in this, the aft air seal marginal portion 41 serves as a fulcrum, so that the tabs 42 may be elevated sufficiently with a modest degree of tilt as where there is little space forward of the floor plate flange 12. In such tilted position the furnace g is then drawn forward (in the direction of the arrow in FIG. 6) until the tabs 42 are beyond the slots 30. The furnace g may then be skidded, as shown in FIG. 5, forwardly out of the alcove or closet space.

The metal-to-metal air seal provided by the present invention is strong and wear-resistant; it obviates the need for manipulating delicate sealing materials which would be damaged by sliding of the furnace in place. During the operation of the furnace it has proved to be adequate; under the pressure of the furnace blower the escape of air is minimized and falls well within commercially acceptable standards.

This disclosure will suggest to persons skilled in the art both alternatives of design, as for example in the flanges utilized, and alternative uses, for example with downflow air conditioning units installed with a counterflow furnace thereabove. This disclosure is therefore not restricted by the detailed description here given of the preferred embodiment.