Patent Publication Number: US-2020300486-A1

Title: Ventilation system with tapered flexible conduit

Description:
RELATED APPLICATION 
     This application makes a claim of domestic priority to U.S. Provisional Patent Application No. 62/821,761 filed Mar. 21, 2019, the contents of which are hereby incorporated by reference. 
    
    
     BACKGROUND 
     Ventilation systems are used to supply environmentally controlled air to the interior of a structure, such as a residential habitation (e.g., a house) or a commercial establishment (e.g., an office building, a warehouse, etc.). A particularly useful type of ventilation system is sometimes referred to as a Whole House Fan (“WHF”) system. 
     A typical WHF system operates to draw cooler outside air through an interior conditioned space of the structure and into an attic or other unconditioned space, after which the air is vented to the surrounding environment. This allows the structure to be convectively cooled at times when the outside temperature is lower than the inside temperature, such as during overnight and early morning hours. WHF systems can often maintain a desired cool interior temperature with little or no need to operate traditional HVAC (heating, ventilation and air conditioning) equipment, producing significant energy cost savings for a user. 
     While WHF systems have been found operable in reducing cooling costs and enhancing indoor comfort, there remains a continual need for improved efficiencies with such systems. It is to these and other advancements that the present disclosure is directed. 
     SUMMARY 
     Various embodiments of the present disclosure are generally directed to an apparatus and method for supplying ventilation to an interior structure. 
     In some embodiments, a tapered conduit is provided to channel airflow from an inlet port to an outlet port. The tapered conduit includes a flexible inner liner and a flexible outer liner. The flexible inner liner has a length of helically formed wire coupled to a flexible membrane. The helically formed wire takes a frusto-conical path so that the flexible inner liner has a continuously decreasing innermost diameter and tapers in cross-sectional area along an overall length thereof. The flexible outer liner includes a layer of flexible material that continuously tapers in cross-sectional area along a length thereof. The flexible outer liner is configured to cover the flexible inner liner to provide acoustic baffling for the airflow passing along the tapered conduit. 
     In related embodiments, an apparatus includes a fan assembly, a register and a tapered conduit. The fan assembly has an electric motor, an exhaust port, and a series of rotatable impellers to establish an air flow through the exhaust port. The register has a base portion configured to extend through a boundary of a structure that separates a conditioned space and an unconditioned space. The register further includes an inlet port coupled to the base portion, with the inlet port having a different cross-sectional area as compared to the exhaust port. The tapered conduit is arranged to extend from the inlet port of the register to the exhaust port of the fan assembly to direct the airflow therebetween. The tapered conduit includes a flexible inner liner surrounded by a flexible outer liner. The flexible inner liner has a length of helically formed wire coupled to a flexible membrane. The flexible outer liner has a layer of flexible material that provides acoustic baffling for the airflow passing along the tapered conduit. The tapered conduit is provided with a frusto-conical shape that extends along an overall length of the conduit to accommodate attachment to the respective exhaust and inlet ports. 
     These and other features and advantages of various embodiments can be understood with a review of the following detailed description in conjunction with a review of the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic depiction of a ventilation system constructed and operated in accordance with various embodiments of the present disclosure. 
         FIG. 2  shows a side elevational depiction of an inner liner of a tapered flexible conduit of the system of  FIG. 1  in some embodiments. 
         FIG. 3  shows a partial cross-sectional view of a portion of the inner liner of  FIG. 2  in some embodiments. 
         FIGS. 4A and 4B  are respective isometric depictions of the inner liner in respective expanded and retracted orientations. 
         FIGS. 5A and 5B  show cross-sectional representations of portions of the inner liner in a fully collapsed orientation in accordance with different tapering rates. 
         FIG. 6  shows a partial cross-sectional view of the tapered flexible conduit in which an outer liner has been configured to surround the inner liner in some embodiments. 
         FIG. 7  is a schematic representation of different layers of material that may be utilized in the outer liner of  FIG. 6  in some embodiments. 
         FIG. 8  shows the outer liner as a closed tapered sleeve configured to slide onto the inner liner to produce the configuration of  FIG. 6 . 
         FIG. 9  shows the outer liner as an open planar piece of material that is wrapped around the inner liner to produce the configuration  FIG. 6 . 
         FIG. 10  shows the use of a fastener mechanism to secure the outer liner into its final shape of  FIG. 6  in some embodiments. 
         FIGS. 11A through 11C  show a methodology in which the inner liner may be advantageously constructed in accordance with some embodiments. 
         FIGS. 12A and 12B  show respective isometric depictions of the register of  FIG. 1  in some embodiments. 
         FIG. 13  is a front facing depiction of the whole house fan of  FIG. 1  in some embodiments. 
         FIG. 14  shows an isometric depiction of the register of  FIG. 1  in further embodiments. 
         FIG. 15  illustrates a rectilinear wire frame formed from a selected end of the coil portion of the inner liner. 
         FIG. 16  shows mating engagement of the wire frame from  FIG. 15  onto the register of  FIG. 14  during installation of the tapered conduit. 
         FIGS. 17A through 17C  illustrate different ventilation system configurations that utilize the tapered conduit in accordance with various embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     Various embodiments are generally directed to improvements to ventilation systems, including but not limited to a Whole House Fan (WHF) system. As explained below, some embodiments provide the ventilation system with a register in a ceiling of a structure at a boundary (ceiling) between an interior of the structure, such as a residential space, and an upper area of the structure, such as an attic. The register may be sized to fit between adjacent ceiling joists, and may have moveable vanes that automatically open when the system is operational and close to seal off the attic when the system is deactivated. 
     A fan is supported at an appropriate clearance location within the attic above the register. The fan may take the form of a low powered, high efficiency WHF having an electric motor which rotates a number of fins (impeller blades) about a central axis to generate a desired airflow rate. 
     A tapered flexible conduit (or “duct”) provides a nominally fluid tight passageway between the register and the fan. The conduit can be any suitable length, such as on the order of from around four (4) to eight (8) feet, to allow the fan and the register to be respectively located at optimum locations. Mounting the fan away from the register in this manner provides certain advantages, including reductions in noise since the fan motor is mechanically decoupled from the framework of the structure, and enhanced efficiency since the fan can be positioned in a location that can generate enhanced airflow within the attic space. 
     It is contemplated that the register has a first overall outermost diameter (OD) at an outlet connection port. The fan has a second overall OD at an inlet connection port. While not limiting, it is contemplated that the first OD of the register will be smaller than the second OD of the fan. Both the outlet port of the register and the inlet port of the fan may be circular in shape, or may take other cross-sectional shapes. 
     The conduit is continuously tapered so as to have a first end with a first innermost diameter (ID) sized to mate with the first OD of the register, and a second end with a second ID sized to mate with the second OD of the fan. In one embodiment, the conduit is nominally seven (7) feet in expanded length and has respective first and second IDs of nominally 20 and 24 inches, which generally correspond to the respective sizes of the register and fan. Other respective sizes can be used. 
     The conduit is contemplated as comprising a two-piece unit with two main elements: an inner liner (or “collapsible shell”) and an outer liner (or “insulative sleeve”). 
     The inner liner comprises a wire wound in a helical shape with a plurality of turns, each successive turn having a slightly smaller OD as compared to the previous turn. This provides the inner liner with a frusto-conical tapered shape bounded by first and second IDs. Bonded to the helical wire is a thin layer of flexible material. Any suitable flexible material may be used. For sound deadening and airflow purposes it is contemplated that the flexible material may be a non-permeable material, but such is not necessarily required. 
     The outer liner may comprise an inner liner of insulation bonded to an outer non-permeable layer. The insulation layer serves to provide the conduit with thermal and/or acoustic insulating capabilities, and the outer non-permeable layer retains the airflow directed through the conduit from the register to the fan. 
     The inner liner may be expanded to an extended orientation and collapsed to a retracted orientation as required. The total amount of length reduction will depend on a number of factors including the extended length, the diameter of the wire, the number of turns in the helical coil, the relative diameter of the respective turns, the flexibility and thickness of the inner liner material, etc. 
     In some cases, the flexible inner liner can be collapsed to an overall length of less than 50% of the extended length. In other cases, the flexible inner liner can be collapsed to an overall length of from about 12% to about 25% of the extended length. In still other cases, the flexible inner liner can be collapsed to an overall length of less than 12% of the extended length. The ability of the inner liner to be collapsed provides a number of operational advantages. These advantages include reduced shipping costs through reduced packaging volume, flexibility in routing of the conduit during installation, and improved ability to maintain the desired conduit shape during the operational life of the system. 
     The outer liner is sized to slide onto or otherwise be attached to the inner liner. By sliding the larger end of the outer liner onto the smaller end of the inner liner, the outer liner can easily slip onto the length of the inner liner to mate these respective elements. Because of the tapered nature of the inner and outer liners, the outer liner will not tend to catch onto the inner liner. 
     In some embodiments, the outer liner is a closed, tapered sleeve that maintains the desired frusto-conical shape for the conduit once installed. In other embodiments, the outer liner is supplied as a planar sheet that is wrapped around the inner liner. Opposing edge surfaces of the planar sheet are adjoined using a suitable fastening mechanism, such as a zipper, hook and loop fasteners, snaps, etc. It will be appreciated that while the inner liner may be easily collapsed to a fraction of its extended length, the bulkiness of the outer liner limits the ability to collapse the outer liner in the longitudinal direction (e.g., the axis along which the tapered flexible conduit extends). Instead, for shipment and storage purposes, the outer liner can be folded or otherwise collapsed into a compact volume. 
     Nevertheless, the outer liner is sufficiently flexible to allow the conduit to be bent or otherwise routed as required to achieve the desired coupling between the register and the fan while retaining the desired tapered internal cross-sectional area along the fluidic path. Moreover, because the outer liner essentially constitutes a sleeve (e.g., a “sock”), the outer liner may be rolled, folded or otherwise collapsed into a suitably small area to allow the collapsed outer liner to be slipped into the interior of the collapsed inner liner for packaging and shipment of both the inner and outer liners as a single compact unit. 
     Attachment mechanisms such as metal or flexible tabs can be provided at the respective ends of the inner and/or outer liners to enable attachment of the inner liner to the outer liner at each end, as well as attachment of the conduit to the respective register and fan connection ports. This ensures that the inner and outer liners, once adjoined together, maintain the tapered flexible conduit as a one piece unit that is light and easy to manipulate. 
     These and other features and advantages of various embodiments can be understood beginning with a review of  FIG. 1  which provides a simplified schematic representation of a ventilation system  100  for use in controlling the internal environment of a building structure  102 . 
     For purposes of providing a concrete illustration, it is contemplated that the ventilation system is a whole house fan (WHF) system and the structure is a residential structure (e.g., a house). Other applications for the various embodiments presented herein are contemplated, however, and will readily occur to the skilled artisan upon review of the present disclosure. These and other applications can include other configurations in a residential setting (including the utilization of an unconditioned interior space such as an attached garage), other configurations in a commercial environment (e.g., an office building, a workshop, a warehouse, etc.). 
     The structure  102  is divided between two main spaces, or areas: an interior area  104  and an attic space  106 . The interior area may comprise one or more rooms on one or more floors adapted for normal human habitation (e.g., kitchen, living room, bedrooms, bathrooms, hallways, etc.). As such, the interior area  104  is referred to as a conditioned space, and may be serviced by an HVAC system (not separately shown). 
     The attic space  106  extends above the interior area and may serve as a storage space for the humans occupying the interior area  104 . As such, the attic space is referred to as an unconditioned space. Different levels of insulation, fit and finish, etc. will tend to exist between the interior area and the attic in a manner well known to the reader. It will be appreciated that the WHF system  110  can be alternatively configured to ventilate to other unconditioned spaces, including but not limited to an attached garage, workshop, etc. 
     The ventilation system  100  includes a register (inlet)  108 , a tapered flexible conduit  110 , and a fan (WHF)  112 . The register  108  is disposed to extend through a ceiling boundary  114  between the interior area  104  and the attic space  106 . The fan  112  is supported within the attic space  106  at a suitable location with adequate clearance and air flow. The conduit  110 , as explained below, provides fluidic communication between the register  108  and the fan  112 . 
     The ventilation system  100  is operated at times when the outside temperature of the external environment is lower than the temperature of the interior area  104 , and it is desirable to apply cooling to the structure  102 . Depending on the climate, this may include periods of operation during Spring, Summer and/or Fall as required. 
     During operation, the fan  112  is activated and the register  108  is opened. This draws in outside airflow, as indicated by arrows  116 , through various apertures in the interior area (e.g., open doors, windows, vents, etc.). The inlet airflow  116  is drawn slowly to collect heat from the interior area and to flow up through the register  108 . 
     This airflow is directed, by the conduit  110 , from the register  108  to the fan  112 . The fan exhausts the heated airflow (represented by arrows  117 ) into the attic space  106 . This operation has the advantage of drawing the heat from the interior area into the attic space. Because the fan establishes a positive pressure within the attic space that is greater than the pressure of the exterior environment, at least a portion of the airflow (arrow  118 ) is vented through various vent apertures in a roof  119  of the structure. 
     Electronic controls (not separately shown) may be configured to automatically detect the differential temperatures between the interior and external environments, and automatically activate the ventilation system  100  at appropriate times. The register may have motorized vanes (not separately shown) that can be moved between closed and open positions so that the attic is sealed off from the interior area when the ventilation system is in a deactivated state. 
       FIG. 2  is a side elevational schematic representation of aspects of the tapered flexible conduit  110 . A flexible inner liner  120  forms an interior portion of the conduit  110 . As further shown in  FIG. 3 , the inner liner  120  comprises a helical coil  122  formed of wire that takes a frusto-conical (cone) shaped path with a continuously reduced cross-section. Bonded to the coil  122  is a thin layer (membrane)  124  of flexible material that, in combination with the wire, provides the inner liner  120  with a frusto-conical shape. The layer  124  may be a permeable material (e.g., cloth, etc.) that allows a portion of the airflow to pass through the layer, or may be a non-permeable material such as a polyester film (e.g., mylar, etc.), rubber, plastic, etc. that restricts passage of airflow through the layer. 
     The flexible nature of the coil  122  and layer  124  are such that the conduit  120  can be transitioned (e.g., stretched and collapsed) between an expanded orientation, as shown in  FIG. 4A , and a retracted orientation, as shown in  FIG. 4B . The coil  122  can be affixed to an interior or exterior surface of the layer  124 . In other embodiments, the coil can be sandwiched between two or more laminated layers. Other configurations can be utilized as well. 
     The inner liner  120  has a smaller first end  128  and a larger second end  129 . The smaller first end  128  is adapted for a substantially airtight fluidic coupling to the register  108 , and the larger second end  129  is adapted for a substantially airtight fluidic coupling to the fan  112 . This arrangement is not necessarily required; in other cases, the smaller end may be affixed to the fan and the larger end may be affixed to the register. 
     A larger diameter fan tends to provide certain advantages including greater efficiency, larger sustained airflow (e.g., greater CFM), etc. On the other hand, the register may be limited to a size that can be placed between or among existing structural members such as spaced-apart joists. A common residential construction spacing is nominally around 16 inches between the centers of adjacent joists, so some registers  108  may be adapted to fit in this intervening space. 
     Hence, while the tapered conduit can be configured to work with substantially any respective fan and register sizes, in most cases the fan will be larger than the register and the conduit will get larger in a direction toward the fan and smaller in a direction toward the register. It will be appreciated that none of the drawings presented here are necessarily drawn to scale, so the amount of tapering between the respective ends  128 ,  129  in a given application may be different from that shown in the drawings. 
     In one embodiment, the conduit  120  has an expanded length of nominally seven (7) feet, a first end with an internal circular diameter of nominally 20 inches, and a second end with an internal circular diameter of nominally 24 inches. In this way, the conduit  120  operates as a continuous reducer (or expander) over the length thereof. Other overall lengths and rates of reduction in cross-sectional size can be used as desired. For example, other embodiments may provide an expanded length of from four (4) to eight (8) feet, a smaller interior diameter of from around 16 inches or less to 22 inches or more, and a larger interior dimeter of from around 20 inches or less to 28 inches or more. 
     The collapsible nature of the inner liner  120  is depicted in  FIGS. 5A and 5B , which shows different configurations for the inner liner in some embodiments.  FIG. 5A  shows each turn in the helical coil  122  to have a reduced cross-sectional diameter at a first rate that is greater than that in  FIG. 5B . While it is contemplated that the inner coil may be fully collapsible so that each coil turn is immediately adjacent, such is not necessarily required; in other embodiments, the inner liner may be only collapsible a moderate amount (such as 50%) as compared to its extended length. 
       FIG. 6  shows the tapered flexible conduit  110  from  FIG. 1  in further detail. An outer liner  130  is configured to surround the inner liner  120 . The inner and outer liners  120 ,  130  cooperate to retain the internal airflow at efficient flow levels and low pressure drops while providing sound deadening characteristics so that fan noise and vibrations are not transmitted through the register to the interior of the structure. 
     The outer liner  130  has a frusto-conical shape that closely matches the shape of the inner liner  120 . To this end, the outer liner  130  has a smaller first end  132  configured for mating to the register and a larger second end  134  configured for mating to the fan. 
     As shown in  FIG. 7 , the outer liner  130  includes an insulation layer  136  and a protective layer  138 . Additional layers can be applied as required. While not limiting, it is contemplated that the insulation layer  136  will be sandwiched between the interior layer  124  of the inner liner  120  (see  FIG. 3 ) and the protective layer  138  of the outer liner  130  ( FIG. 7 ). 
     Any suitable materials can be used to form the outer liner  130 ; for example, the insulation layer  136  can incorporate batting, cloth, fibers, plastic, rubber, foam, thermal insulation material, or any other material or combination of materials that provide suitable acoustic and/or thermal baffling characteristics. The exterior layer  138  can incorporate mylar, plastic, metal foil, rubber or any other material or combination of materials that serve to provide fluidic channeling and protective characteristics. 
     It is contemplated that the protective layer  138  will be a non-permeable material, but such is not necessarily required; other suitable materials include cloth, etc. can be used. Nevertheless, it may be desirable that at least one, or both, of the respective layers  124  and  138  be non-permeable material. In an alternative embodiment, the outer liner  130  can be formed of homogenous layer of material (e.g., a conically shaped rubber sheaf, etc.). In still other embodiments, a laminate having more than two layers can be used to form the outer liner. 
     The outer liner  130  can be arranged as a closed tapered sleeve as shown in  FIG. 8 . In this way, the larger end  134  of the outer liner  130  can be slipped onto the smaller end  128  of the inner liner  120  like a sock. In other embodiments, the outer liner  130  may be arranged as an open planar sheet  140  that can be wrapped around the inner liner  120 , as shown in  FIGS. 9 and 10 . A fastening mechanism  142  can be used to adjoin the opposing edges of the planar sheet  140  ( FIG. 10 ). The fastening mechanism  142  can take any variety of forms including a zipper, a hook and loop fastener, a series of snaps, etc. Retention tabs  144 ,  146  ( FIG. 9 ) may be provided at the respective ends  132 ,  134  of the outer liner  130  to interconnect with the respective ends  128 ,  129  of the inner liner  120  and maintain the inner liner  120  in the desired configuration within the outer liner  130 . 
       FIGS. 11A through 11C  illustrate a sequence whereby the inner liner  120  may be fabricated in some embodiments. Other sequences may be used so these are merely for purposes of illustration and are not limiting. As shown in  FIG. 11A , a form (last)  150  is provided with an outermost frusto-conical surface  152  sized to correspond to the dimensions of the inner liner  120 . 
     As shown in  FIG. 11B , a sheet of material  154  is wrapped around the outer surface  152  from a roll dispenser  156 . The material  154  corresponds to the flexible thin layer  124  of  FIG. 3 . In  FIG. 11C , coils of wire  158  are wrapped around and onto the material  154  at the desired spacing using a wire dispenser to form the helical coil  122 . Subsequent processing such as glue or heat bonding is applied to secure the wire to the material. It will be noted that while the wire has been shown to extend on the outside of the material, other arrangements can be used such as placement of the wire on the inside of the material, the use of multiple material layers, sandwiching the wire between opposing material layers, etc. 
       FIGS. 12A and 12B  show a register  160  generally corresponding to the register  108  in  FIG. 1  in accordance with some embodiments. Other arrangements can be used. The register  160  has a rectilinear (rectangular) base portion  162  and a cylindrical outlet port  164 . The port  164  has a cylindrical outer surface  166  configured to slide within the smaller end  128  of the inner liner  120  and smaller end  132  of the outer liner  130 . 
     As depicted in  FIG. 12B , the register  160  further has a number of controllably movable vanes  168 . The vanes can be transitioned between an open position to permit the ingress of air from the interior area and a closed position to close off the ingress of air from the interior area. A motor driven actuation system may be included to automatically transition between the closed and open positions. 
       FIG. 13  is a front facing view of a fan  170  generally corresponding to the fan  112  in  FIG. 1 . The fan  170  includes an outermost housing  172  which encloses a series of fan impellers  174  that are rotated by an electric motor  176  to establish a desired airflow. The housing  172  serves as an inlet port and includes a cylindrical outer surface  178  configured to slide within the larger end  129  of the inner liner  120  and the larger end  134  of the outer liner  130 . 
     While the register and fan ports  164 ,  172  will be sized to nominally allow the tapered flexible conduit  110  to nominally slip onto these ports, manufacturing variations and other factors may give rise to situations where a small mismatch occurs. For example, instead of providing the fan with a nominal OD of 20 inches, an actual fan may be slightly larger, such as 20¼ inches. The tapered nature of the conduit  110  allows an installer to trim off an appropriate amount of the end of the conduit until the desired interior diameter is reached, after which the appropriately sized end can be slipped onto the fan and establish a fluid-tight seal. Similar adjustments can be made to handle variations in register sizes. To accommodate these and other considerations, in some cases the larger end of the conduit may be made slightly larger than needed and the smaller end of the conduit may be made slightly smaller than needed. 
     As noted above, the register and fan ports  164 ,  172  in  FIGS. 12A, 12B and 13  each have a cylindrical shape. This allows the circular ends of the tapered conduit  110  to slip onto these respective elements to establish a substantially fluid tight seal at each end. A suitable fastening mechanism (e.g., tape, adhesive, clamps, threaded fasteners, etc.) can be applied to secure each end of the conduit to the respective port. 
     It is contemplated that some installation environments may have a register and/or a fan port that is not cylindrically shaped. Instead, one or both of these ports may have some other shape, such as a rectilinear (rectangular) shape. To this end,  FIG. 14  shows another register  180  generally similar to the registers  108 ,  160  discussed above. The register  180  has a rectilinear base portion  182  and a rectilinear outlet port  184 . The port  184  has four (4) flat outer surfaces  186 . In the present example, the rectangular cross-sectional opening through the port  184  is square (e.g., each outer surface  186  is the same size). Other shapes can be accommodated including an elongated configuration (e.g., two of the outer surfaces may be longer than the remaining two surfaces), an oval configuration, etc. 
     To enable the inner liner  120  of the tapered conduit  110  to mate with the outlet port  184 , the circular turns of the coil  122  can be bent by the installer into a matching wire frame  188 , as generally represented in  FIG. 15 . A suitable number of turns can be shaped into the wire frame to accommodate the protrusion length of the port. 
     As generally depicted in  FIG. 16 , the write frame  188  can be slipped onto and attached to the rectilinear port  184 . A short transition portion  190  will extend from the wire frame  188 , allowing the conduit  110  to transition from a square shape to a tapered, frusto-conical shape  192  along a remaining extent of the conduit. While the outer liner is not shown in  FIG. 16 , it will be understood that, as described above, the outer liner can be installed onto the inner liner either before or after the wire frame  188  is attached to the rectilinear port  184 . 
       FIGS. 17A-17C  show respective ventilation system configurations that can be realized using a tapered conduit constructed and operated in accordance with various embodiments.  FIG. 17A  shows a first ventilation system  200 A with a tapered conduit  202 , a register  204  and a fan  206 . The register  204  extends through a horizontally extending structural boundary  208 , such as a ceiling that separates an interior space from an attic. These respective elements generally correspond to similar elements discussed above. 
     The ventilation system  200 A takes a vertical, axially aligned configuration so that the fan  206  is suspended directly above, and in line with, the register  204 . More particularly, axis  210  represents a centerline of the register port, and axis  212  represents a centerline of the fan port. The axes  210 ,  212  are colinear and extend along the same overall axial line of the conduit  202 . 
       FIG. 17B  shows a vertical, axially offset configuration so that the fan  206  is up and off to the side of the register  204 . This causes the conduit  202  to be routed along a continuously curving, serpentine (e.g., S-shaped) path. The flexibility of the conduit allows both the register and the fan to be separately placed in optimal locations. 
     For example, it is contemplated that the register  204  in  FIG. 17B  has been placed in a desired location to fit between a pair of adjacent joists or other structural members (not separately shown) in the boundary  208 . The fan  206  has been offset under an overhead truss member (not separately shown) which supports the fan using a chain, a set of straps, or some other suitable mounting mechanism. 
     While vertical orientations for the conduit have been illustrated in the drawings, the conduit has sufficient rigidity in a plane transverse to the direction of airflow (e.g., orthogonal to axes  210 ,  212 ) that the conduit can be installed in any desired orientation. 
     To this end,  FIG. 17C  provides a ventilation system  200 C with a horizontal, axially aligned configuration. In this case, the register  204  extends through a vertically extending boundary  208  such as a wall adjacent a walk-in attic space, a garage, etc. The fan  206  and the conduit  202  can be secured and supported as needed. 
     It follows that the flexible nature of the tapered conduit  110  allows mating with any number of different port sizes, shapes and mounting locations without the need for the use of a reducer or other transition member to accommodate changes in size (e.g., larger to smaller diameter) or shape (e.g., square to round, etc.). The tapered conduit can be trimmed at either end to obtain an inner circumference that meets the needs of substantially any installation environment. This includes the installation of a new ventilation system as well as the retrofitting of an existing ventilation system. 
     It will now be appreciated that the tapered flexible conduit as embodied herein can provide a number of benefits over the existing art, including efficiencies that can be realized during manufacturing, shipment, installation and operation. While the various embodiments have contemplated the environment of a whole house fan (WHF) system in a residential structure, other applications may be used as well, including but not limited to commercial structures, industrial applications, etc. 
     It is to be understood that even though numerous characteristics and advantages of various embodiments of the present disclosure have been set forth in the foregoing description, together with details of the structure and function of various embodiments of the disclosure, this detailed description is illustrative only, and changes may be made in detail, especially in matters of structure and arrangements of parts within the principles of the present disclosure to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.