Abstract:
A fireplace chimney cap includes a body having first and second apertures in fluid communication defining a first cavity therebetween. The first cavity is configured and disposed to receive combustion air through the first aperture, then through the second aperture for delivery to a fireplace combustion chamber. The body has third and fourth apertures in fluid communication defining a second cavity therebetween. The second cavity is configured and disposed to receive combustion gases from the fireplace combustion chamber through the third aperture, then through the fourth aperture for exhausting exterior of the body. The first and second cavities are fluidly separated from each other. The first and fourth apertures are configured and disposed to provide a pitot effect to more readily draw both combustion air into the first cavity and combustion gases into the second cavity in response to the first aperture disposed upwind and fourth aperture position disposed downwind.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This Application is a continuation in part of application Ser. No. 11/618,756, filed Dec. 30, 2006, Attorney Docket No. 2006-030, entitled “FIREPLACE HEAT EXCHANGER” and which is incorporated by reference in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates generally to fireplace accessories and, more particularly, to a fireplace chimney cap adaptable to a wide array of fireplace sizes and useful for improving the heating efficiency of a fireplace. 
       BACKGROUND OF THE INVENTION 
       [0003]    Conventional fireplaces are inefficient sources of heat for the room in which they are located as the majority of the heat generated by the combustion process escapes through the chimney. Fireplace fires also require large volumes of combustion air, which if drawn from the interior space of the room, result in significant heat loss from the room as heated room air is also exhausted through the chimney. Cold air drafts in the interior space also result since the heat loss through the chimney causes cold air to be drawn in from the outside through door and window openings. 
         [0004]    In an effort to increase the efficiency of fireplaces, fireplace inserts have been used. These devices generally comprise a large metal box situated within the fireplace and extending into the room in which the fireplace is located. Wood or other fuel is burned within the large metal box, which has openings for supplying combustion air and for expelling combustion gases to the chimney. Room air circulated within the large metal box is heated and returned to the room without commingling with the combustion air stream. While such inserts have been designed to retain the visual appeal and rustic charm of an open flame, their heat transfer efficiency is limited, allowing substantial amounts of energy to be exhausted through the chimney to the outside. 
         [0005]    U.S. Pat. No. 4,357,930 and its progeny disclose a fireplace heating system for heating the room air incorporating a compact heat exchanger mounted at the top portion of the combustion chamber of the fireplace and extending across the location where the chimney flue connects with the top portion of the combustion chamber. A conventional fireplace door may be used to prevent room air from being exhausted through the chimney and isolate hotter portions of the fire from accidental contact by room occupants. A fan is provided for circulating room air through the heat exchanger in a manner so that the hot combustion gases heat up the room air being circulated therethrough without commingling. The design of the compact heat exchanger directs hot combustion gases through tortuous pathways to increase heat transfer; the complex design of the pathways results in increased fabrication costs for the heat exchanger assembly compared to more conventional heat exchange methods. 
         [0006]    It would be desirable to provide an improved fireplace heating and venting system suitable for use in existing or newly constructed fireplaces that further increases thermal efficiency of a fireplace, reduces the amount of heat energy exhausted through the chimney flue, generating reduced levels of noise during operation and that can be economically fabricated from inexpensive, yet durable materials. 
       SUMMARY OF THE INVENTION 
       [0007]    The present invention relates to a fireplace chimney cap including a body having a first aperture and a second aperture in fluid communication defining a first cavity therebetween. The first cavity is configured and disposed to receive combustion air through the first aperture and then through the second aperture for delivery to a fireplace combustion chamber. The body further has a third aperture and a fourth aperture in fluid communication defining a second cavity therebetween. The second cavity is configured and disposed to receive combustion gases from the fireplace combustion chamber through the third aperture and then through the fourth aperture for exhausting exterior of the body. The first and second cavities are fluidly separated from each other. The opposed first and third apertures are configured and disposed to provide a pivot effect to more readily draw both combustion air into the first cavity and combustion gases into the second cavity in response to the first aperture disposed upwind and fourth aperture disposed downwind. 
         [0008]    The present invention additionally relates to a fireplace chimney cap including a body having a first aperture and a second aperture in fluid communication defining a first cavity therebetween. The first cavity is configured and disposed to receive combustion air through the first aperture and then through the second aperture for delivery to a fireplace combustion chamber. The body further has a third aperture and a fourth aperture in fluid communication defining a second cavity therebetween. The second cavity is configured and disposed to receive combustion gases from the fireplace combustion chamber through the third aperture and then through the fourth aperture for exhausting exterior of the body. The first and second cavities are fluidly separated from each other and first aperture is disposed upwind and fourth aperture is disposed downwind. 
         [0009]    The present invention further relates to a method of installing a fireplace chimney cap to a chimney flue. The steps include providing a body having a first aperture and a second aperture in fluid communication defining a first cavity therebetween. The first cavity is configured and disposed to receive combustion air through the first aperture and then through the second aperture for delivery to a fireplace combustion chamber. The body further has a third aperture and a fourth aperture in fluid communication defining a second cavity therebetween. The second cavity is configured and disposed to receive combustion gases from the fireplace combustion chamber through the third aperture and then through the fourth aperture for exhausting exterior of the body, the first and second cavities fluidly separated from each other. The method further includes selectably installing a blower in at least one of the first and second cavity. The method further includes securing the body to a chimney flue with the first aperture facing a predetermined wind direction thereby establishing a pivot effect to more readily draw both combustion air into the first cavity and combustion gases into the second cavity. 
         [0010]    The present invention yet further relates to a fireplace venting system including a heat exchanger assembly having a combustion chamber, a chimney flue having an opening connected to a top portion of the combustion chamber, a heat source disposed within the combustion chamber for producing hot gases in response to combustion, a front opening, and a fire screen assembly or the like for closing the front opening to separate the combustion chamber from an area to be heated. The heat exchanger assembly includes a baffle for sealing the chimney opening, the baffle having at least one flue opening for exhausting combustion gases into the chimney flue and at least one combustion air supply opening for receiving combustion air into the combustion chamber. At least one elongated heat exchanger core has an outer hollow member with opposing combustion gas inlet and outlet ends separated by an outer member length, and an inner hollow member disposed within and generally coextensive with the outer hollow member forming an annular passageway therebetween. The inner hollow member has a medium inlet end and a medium outlet end, and further defining an interior passageway for a heat transfer medium flowing generally from the medium inlet end toward the medium outlet end. At least a portion of combustion gas flow within the annular passageway is generally in a counter-flow heat exchange relationship with the medium flow within the inner hollow member. The annular passageway receives combustion gases from the combustion chamber at the gas inlet end and discharging combustion gases from the gas outlet end. At least one nozzle disk is configured and disposed in the annular passageway to induce a swirling flow pattern of the combustion gases about the inner hollow member generally between the combustion gas inlet and outlet ends. A supply conduit is in flow communication with the medium inlet end for directing a flow of the heat transfer medium toward the medium inlet end of the inner hollow member. A return conduit is in flow communication with the medium outlet end for receiving the heat transfer medium from the medium outlet end of the inner hollow member. A fireplace chimney cap includes a body having a first aperture and a second aperture in fluid communication defining a first cavity therebetween. The first cavity is configured and disposed to receive combustion air through the first aperture and then through the second aperture for delivery to the fireplace combustion chamber. The body further has a third aperture and a fourth aperture in fluid communication defining a second cavity therebetween. The second cavity is configured and disposed to receive combustion gases from the fireplace combustion chamber through the third aperture and then through the fourth aperture for exhausting exterior of the body. The first and second cavities are fluidly separated from each other. The opposed first and third apertures are configured and disposed to provide a pivot effect to more readily draw both outside air into the first cavity and flue gas into the second cavity in response to the first aperture disposed upwind and fourth aperture disposed downwind. 
         [0011]    An advantage of the present invention is a fan/motor arrangement for drawing air through the chimney flue to the combustion chamber of a fireplace system and for drawing combustion gases from the combustion chamber through the chimney flue, which arrangement operating at a substantially reduced noise level as measured adjacent to the combustion chamber. 
         [0012]    A further advantage of the present invention is a fireplace chimney cap that provides a pivot effect which improves operational efficiency associated with movement of combustion air and combustion gases through the fireplace system. 
         [0013]    A still further advantage of the present invention is a blower fan/motor arrangement for drawing combustion gases from the combustion chamber through the chimney flue of a fireplace system, which system will operate at a substantially reduced noise level. 
         [0014]    A yet further advantage of the present invention is a blower fan arrangement making possible a chimney of significantly reduced height. In one embodiment, ranch style residential dwellings may be constructed without requiring disproportionably high chimneys. Architects may then incorporate workable masonry fireplaces in their designs, such as a top floor in a dwelling having vista living/den rooms or bed room. 
         [0015]    Other features and advantages of the present invention will be apparent from the following more detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1  is a perspective view of a fireplace venting system of the present disclosure. 
           [0017]      FIG. 2  is a perspective view of a fireplace of the present disclosure. 
           [0018]      FIG. 2A  is an exploded view of the fireplace of  FIG. 2  of the present disclosure. 
           [0019]      FIG. 3  is a partial cutaway view taken along line  3 - 3  of  FIG. 2  of the present disclosure. 
           [0020]      FIG. 4  is a partial cutaway view taken along line  4 - 4  of  FIG. 2  of the present disclosure. 
           [0021]      FIG. 5  is a partial cutaway view taken along line  5 - 5  of  FIG. 2  of the present disclosure. 
           [0022]      FIG. 6  is a partial cutaway view taken along line  6 - 6  of  FIG. 2  of the present disclosure. 
           [0023]      FIG. 6A  is a partial cutaway view taken along line  6 - 6  of  FIG. 2  of the present disclosure. 
           [0024]      FIG. 7  is a partial cutaway view taken along line  7 - 7  of  FIG. 1  of the present disclosure. 
           [0025]      FIG. 7A  is an elevation view of an alternate embodiment of  FIG. 7  of the present disclosure. 
           [0026]      FIG. 8  is a cross-section taken along line  8 - 8  of  FIG. 1  of the present disclosure. 
           [0027]      FIG. 9  is an embodiment of a nozzle disk of  FIG. 2  of the present disclosure. 
           [0028]      FIG. 10  is a partial cross-section taken along line  10 - 10  of  FIG. 9  of the present disclosure. 
       
    
    
       [0029]    Other features and advantages of the present invention will be apparent from the following more detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0030]    In  FIGS. 1 ,  2  and  2 A, there is shown a perspective view (and an exploded perspective view in  FIG. 2A ) of a fireplace  5  comprising a combustion chamber  10  having a front opening  12  ( FIG. 2 ), a back wall  14 , a pair of side walls  16 , a hearth  18 , and a chimney  21  including a chimney flue  20  connected to the top portion of the combustion chamber  10  by a throat or chimney opening  19 . Combustion gases  37  produced in combustion chamber  10  are discharged through the chimney flue  20  by way of the throat or chimney opening  19 , and then through a chimney cap  102 . In one embodiment, fireplace venting system  3  conveys relatively cold outside air or combustion air  35  through chimney cap  102  and then through chimney flue  20  to combustion chamber  10 , as will be discussed in further detail below. 
         [0031]      FIGS. 1 and 2  further shows a suitable type of gas log burner  30  for producing heat energy that is supplied with heating gas from an external source. These gas log burners  30  are well known in the art and various suitable alternate types may be employed. Also provided is a conventional fireplace screen  24 , which closes and substantially seals front opening  12 , thereby separating combustion chamber  10  from a room or area to be heated by fireplace  5 . In one embodiment, fireplace screen  24  includes glass doors or other substantially optically transparent structure that allow room or area occupants to observe the combustion flames and that may be opened to access the combustion chamber  10  or for cleaning the fire screen assembly. However, fireplace screen  24  also includes translucent or opaque constructions in alternate embodiments. 
         [0032]    In one embodiment, combustion air  35  enters combustion chamber  10  via a pair of conduits  31  adjacent to and is supplied to gas log burner  30 . Conduits  31  are controllably spaced adjacent to supply conduit  80  and above hearth  18  by clamps  39  secured in side walls  16 . When the fireplace is not used for extended period of time, such as during the summer months, clamps  39  are loosened and the ends of conduits  31  are directed toward hearth  18 . When the ends of conduits  31  are brought into abutment with hearth  18 , access to combustion chamber  10  through conduits  31  is substantially blocked, preventing insect access into the dwelling through the chimney. In one embodiment, as shown in  FIG. 3 , end portions  41  of conduits  31  are angled toward back wall  14  and hearth  18  to provide a swirling movement of combustion air  35  within combustion chamber  10 . The hot combustion gases  37  produced by gas log burner  30  will flow upwardly from the location of the burner combustion immediately above the hearth  18 , which upwardly flowing gases being confined by back and side walls  14 ,  16  of the fireplace and fireplace screen  24 . Fireplace elements are well known in the art and are discussed extensively in U.S. Pat. Nos. 4,357,930, 4,471,756, and 6,047,695, all by Eberhardt and which are incorporated by reference in their entirety herein. 
         [0033]    In accordance with the invention, as shown in  FIGS. 2 ,  2 A and  4 , there is provided a heat exchanger assembly  40  comprising one or more elongated heat exchanger cores  42  and means for mounting the same within combustion chamber  10 , generally adjacent to back wall  14 . In one embodiment, heat exchanger assembly  40  is substantially vertically oriented. Heat exchanger assembly  40  incorporates a plurality of heat exchanger cores  42  to enable efficient thermal energy exchange between a heat transfer medium  52 , such as room air, and combustion gases  37  by virtue of non-mixing adjacent flow within the heat exchanger assembly  40 . As shown in  FIG. 1 , flue baffle  22  is positioned to extend across the throat or chimney opening  19  in the top portion of the combustion chamber  10  to seal the connection between combustion chamber  10  and chimney flue  20 . At least one flue opening  28  is provided in baffle  22  to provide combustion gases  37 , created when the gas log burner  30  is in operation, a controlled passage from combustion chamber  10  to chimney flue  20 . In addition, as further shown in  FIG. 1 , a pair of combustion air supply openings  29  formed in baffle  22  provide a controlled passage of combustion air  35  drawn from exterior of chimney cap  102  and directed within chimney flue  20  to reach combustion chamber  10 , once the combustion air flows through respective conduits  31 . 
         [0034]    Elements of heat exchanger assembly  40  may be held in position by anchoring tabs (not shown) secured directly into the walls  14 ,  16  of the fireplace which provide connection points for elements of the heat exchanger assembly. Such anchor tabs are suitable for use in fireplaces being modified to use the present invention or fireplaces initially constructed to use the invention. Alternatively, a free-standing support structure may be provided to enable the heat exchanger assembly  40  to be self-supporting within the fireplace, thereby eliminating the need to breach the interior walls of the fireplace with additional fasteners. The design of a free-standing support structure is ideally suited for retrofit applications and is, therefore, adjustable to suit a variety of fireplace sizes and configurations. Materials selected for support members, whether a free-standing frame or anchor tabs, are typically iron or steel and are selected for their durability when exposed to hot combustion gases in the fireplace and relatively low cost. However, support members may be composed of other suitable materials. 
         [0035]    Referring now to  FIGS. 2-4 , heat exchanger assembly  40  comprises six heat exchanger cores  42  as configured for use in a typical fireplace. In one embodiment, cores  42  are generally straight between opposing ends, arranged generally parallel and generally vertically positioned adjacent the back wall  14  of the combustion chamber  10 . Each heat exchanger core  42  includes an elongated inner hollow member  44  surrounded by a substantially coextensive outer hollow member  46  forming an annular passageway  48  therebetween. Both hollow members  44 ,  46  preferably have generally circular cross-sections to allow smooth flow of combustion gases  37  and the heat transfer medium  52  (air in the embodiment described herein), though other shapes or other heat transfer mediums may be used with reasonable effectiveness. In one embodiment, each core  42  is configured to accept flow of combustion gases  37  and heat transfer medium  52  in a counter-flow arrangement, that is, the direction of flow of heat transfer medium  52  in inner hollow member  44  is in a direction generally opposite of the flow of combustion gases  37  through the outer hollow member  46  for improved heat exchange performance therebetween. 
         [0036]    As shown in  FIGS. 4 and 6 , the heat exchanger cores  42  are configured and disposed so that adjacent outer hollow members  46  abut each other along the longitudinal direction, or direction of elongated length. There are three pairs of cores  42  in which combustion gases  37  flow in a downward helical direction through annular passageway  48  of one core  42 . Upon reaching transition region  61 , the direction of flow of combustion gases  37  is reversed so that the combustion gases  37  flow in an upward helical direction through annular passageway  48  of the adjacent core  42  of the pair of cores  42 . The change in direction of combustion gases is shown in  FIGS. 4 ,  5  and  6 A. 
         [0037]    As previously discussed, hot combustion gases  37  traveling within passageways  48  ( FIGS. 4 and 6 ) of heat exchanger cores  42  toward the bottom of combustion chamber  10  are redirected to flow within passageways  48  of adjacent heat exchanger cores  42  toward the top of combustion chamber  10 . As further shown in  FIGS. 1 ,  2 ,  4  and  6 A, once the combustion gases  37  approach the top of heat exchanger assembly  40 , combustion gases  37  passing through combustion gas outlet opening  96  are directed inside a plenum  54  having a vane  67 . Vane  67  divides plenum  54  into passageways  56  and  57 . Passageway  56  receives combustion gases  37  from annular passageway  48  and passageway receives heated heat transfer medium  53  from inner hollow member  44 . As shown in  FIG. 2A , plenum  54  includes a pair of slots  55  (one slot shown in  FIG. 2A ), each slot receiving a corresponding pin  59  of a pair of pins  59  (one pin shown in  FIG. 2A ) formed in an insert  60 . The resulting pivoting connections formed between plenum  54  and insert  60  accommodate the range of angles between back wall  14  and flue baffle  22 . Insert  60  includes a tube having a vane  62  terminating at an end cap  77  which forms a chamber  63  that is in fluid communication with fitting  71  secured to the exterior of insert  60 . A conduit portion  68  is configured to receive conduit portion  66 . Collectively, as shown in  FIG. 2A , insert  60 , and conduit portions  66 ,  68  define return conduit  90 . 
         [0038]    In operation, as shown in  FIGS. 1 ,  2 A and  6 A, plenum  54  is disposed between heat exchanger core  42  and insert  60  such that combustion gases  37  passing through combustion gas outlet opening  96  are directed through passageway  56  and then into chamber  63  of insert  60 . Plenum  54  and insert  60  form an overlap  78  in which vane  67  of plenum  54  and vane  62  of insert  60  form a substantially fluid tight seal to substantially prevent combustion gases  37  from mixing with heated heat transfer medium  53 . In one embodiment, the curves defining passageway  56  act to preserve a portion of the momentum of the flow of combustion gases  37 . Combustion gases  37  entering chamber  63  then flow through opening  64  of insert  60 , then through fitting  71  of insert  64 , which extends through flue opening  28  formed in flue baffle  22 . 
         [0039]    The conventional throat or chimney opening  19  is sealed in the present disclosure by the presence of flue baffle  22 . As a result, all hot combustion gases  37  are directed through the heat exchanger assembly  40  prior to being discharged into chimney flue  20 . In one embodiment, one end of conduit  33 , such as flexible aluminum tubing, is secured over fitting  71  that extends through flue opening  28 , with the other end secured to an inlet aperture  112  of chimney cap  102  that is in fluid communication with an outlet aperture  114  for discharging combustion gases  37  exterior of fireplace venting system  3 . In other words, combustion gases  37  are confined to flow inside conduit  33  and do not mix with combustion air  35  passing through chimney cap  102  and into chimney flue  20 , which combustion air  35  being conveyed to combustion chamber  10 . 
         [0040]    As shown in  FIGS. 1 ,  7  and  8 , chimney cap  102  includes a body  104  defining a substantially trapezoidal profile extending in a longitudinal direction, i.e., the direction of primary length. Body  104  contains partitioned cavities  110 ,  116  disposed therein for separately receiving combustion air  35  and discharging combustion gases  37  therethrough. A louvered inlet aperture  106  including vanes  120  disposed therealong is formed in body  104  for receiving combustion air  35  into cavity  110  from exterior of body  104 . Adjacent to inlet aperture  106  is a partial partition  122  that is proximate to a full partition  118 . In one embodiment, the louvers of inlet aperture  106  are spaced to prevent access, such as by birds. 
         [0041]    Partial partition  122 , which may span body  104  in the transverse direction in one embodiment, prevents rain or other form of moisture from entering cavity  110  and provides additional structural stiffness to body  104 . Full partition  118 , shown as including three panel segments joined along their edges and disposed at angles from each other, forms a contiguous wall in body  104  to separate cavity  110  from another cavity  116 . An outlet aperture  108  ( FIG. 8 ) is disposed between full partition  118  and partial partition  122  for discharging combustion air  35  received into cavity  110  through inlet aperture  106 . Combustion air  35  discharged from outlet aperture  108  flows within chimney flue  20  toward combustion chamber  10 . 
         [0042]    Body  104  also includes cavity  116  having an inlet aperture  112  ( FIG. 8 ) for receiving combustion gases  37  from combustion chamber  10  via conduit  33 . In one embodiment, a transition fitting or adapter  126  ( FIG. 7 ) permits connection of conduit  33  and a blower  128  secured inside cavity  116 . Blower  128  draws combustion gases  37  through conduit  33  and then inside cavity  116  through inlet aperture  112 , finally discharging the combustion gases exterior of body  104  through louvered outlet aperture  114  having vanes  120 . In one embodiment, the louvers of outlet aperture  114  are spaced to prevent access, such as by birds. 
         [0043]    As shown, inlet aperture  106  and outlet aperture  114  are opposed from each other, separated from each other by a flue liner  124  ( FIG. 7 ) when chimney cap  102  is installed. Due to the opposed construction, in response to orienting inlet aperture  106  so that inlet aperture  106  is disposed upwind or faces the general direction of the wind, i.e., the northwest in many portions of North America, body  104  experiences a pivot effect with respect to each of inlet aperture  106  and outlet aperture  114 . That is, when inlet aperture  106  is oriented to face the wind, the relative atmospheric pressure developed outside of but in close proximity with cavity  110  is increased with respect to the relative atmospheric pressure developed inside cavity  110 , due to the combustion air  35  colliding with flue liner  124 , thereby drawing combustion air  35  through inlet aperture  106  and into cavity  110 . Conversely, when outlet aperture  114  is disposed downwind or oriented to face opposite the wind, the relative atmospheric pressure developed outside of but in close proximity with cavity  116  is reduced with respect to the relative atmospheric pressure developed inside cavity  116 , due to the wind flowing around flue liner  124 , thereby drawing combustion gases  37  from cavity  116  through outlet aperture  114 . 
         [0044]    It is to be understood that the term “facing the wind” or “facing upwind” in reference to apertures  106  and  114  is intended to include circumstances in which a plane (not shown) defining apertures  106  and  114  are disposed at an angle to the direction of travel of the wind, including parallel to the wind, and also includes circumstances in which apertures  106  and  114  are disposed to the wind at angles different from parallel. With assistance of a sustained pivot effect, the load required by blower  128  to discharge combustion gases  37  from conduit  33  through and then exterior of chimney cap  102  is reduced. 
         [0045]    The pivot effect may be enhanced through the use of vanes  120  staggered to be disposed upwind or directly face the wind. That is, as shown in  FIG. 7 , a plane  130  of inlet aperture  106  is disposed at an angle θ to the horizontal. Thus, wind that is horizontally disposed combustion air  35  strikes each of vanes  120  distributed over inlet aperture  106 , thereby enhancing the pivot effect described above. It is to be understood that vanes  120  may be of similar or of different sizes, so that a portion of each vane is directly exposed to wind emanating from a predominant direction and orientation, such as horizontally oriented wind from the northwest. For example, as shown in  FIG. 7A , vanes  120  are substantially planar, versus being curved in  FIG. 7 . In addition, vanes  120  in  FIG. 7A  are entirely contained within respective cavities  110 ,  116 . 
         [0046]    As shown in  FIGS. 7 and 8 , chimney cap  102  includes features permitting use with differently configured blowers  128 . That is, chimney cap  102  can accommodate different blower sizes and shapes. Adjustable fastening members  134 , such as threaded rod, and associated mating fastener members  136 , such as jam nuts, may be used to secure blower  128  via a blower flange  138  and openings  132  formed in body  104 . In one embodiment, the pattern of openings in blower flange  138 , openings  132  and openings  148  of chimney cap  102  are substantially identical, and plate  152  is separable from body  104 . 
         [0047]    In one embodiment, adjustable brackets  142  support chimney cap  102  and include opposed pairs of brackets  142  that are disposed on opposite ends of flue liner  124 . The opposed pairs of brackets  142  include slots  144  for use with mating fasteners  150  to accommodate differently sized flue liners  124 . Additionally, brackets  142  include fasteners  146 , such as set screws, for securing brackets  142  and chimney cap  102  in position to flue liner  124 . Moreover, brackets  142  secure a transition fitting or adapter  126  between blower  128  and conduit  33 , such as a reducer, which transition fitting or adapter  126  structurally supports the weight of conduit  33 . 
         [0048]    In one non-limiting method of assembly of chimney cap  102  to flue liner  124 , transition fitting or adapter  126  is secured to each opposed pair of brackets  142 , then conduit  33  is secured to transition fitting or adapter  126  prior to lowering conduit  33  inside of flue liner  124 . Once conduit  33  has been lowered, the opposed pairs of brackets can then be secured to flue liner  124  with fasteners  146 , such as set screws. In one embodiment, plate  152  is separable from body  104 . Plate  152  is secured via openings  132  to such as respective openings (not shown) formed in brackets  142  using fastening members  134  and  136 , such as respective threaded rod and jam nuts, as shown, which fastening members are further utilized to secure flanges  138  to blower  128 . At this point, in one embodiment, four ends of fastening members  134  extend upwardly. Body  104  is then lowered over fastening members  134 , aided by guides  140  so that ends of fastening members  134  extend through corresponding openings  148  aligned with the guides. Assembly is then completed by securing fasteners  154 , such as cap screws, over each fastening member  134 . 
         [0049]    Referring back to  FIGS. 2 ,  2 A and  3 - 6 , each heat exchanger core  42  is made of a material to provide a highly heat conductive arrangement. To that end, inner hollow member  44  is constructed of a heat conductive material, such as aluminum, to effectively conduct heat from the hot combustion gases  37  flowing through the annular passageway  48  to the heat transfer medium  52  flowing through the inner hollow member  44 . Outer hollow member  46 , which is directly exposed to the combustion occurring at burner  30 , is likewise constructed of a highly heat conductive material, but one that is also more suitable for the combustion chamber environment, such as steel and, more specifically, stainless steel. 
         [0050]    In one embodiment, the heat exchanger assembly  40  is configured such that inlet and outlet openings  86 ,  96  for the inner hollow members  44  and the annular passageways  48  are generally adjacent and proximate to a common end of the assembly  40 . 
         [0051]    In one embodiment, the aluminum inner hollow members  44  and other aluminum parts of the heat exchanger cores  42  are anodized flat black. This improves the heat transfer properties of these parts by improving the heat transfer coefficient thereof. The overall heat transfer effectiveness of the heat exchanger assembly  40  is improved by the addition of a radiant energy reflector  65  to at least a portion of the heat exchanger assembly  40 . In one embodiment, radiant energy reflector  65  is a contiguous component as shown in  FIG. 2A , simultaneously serving as an access cover for blower or fan/motor assembly  100 , although multiple reflectors may be used. The radiant energy reflector  65  may be in the form of a reflective covering, such as polished stainless steel or the like, on at least a portion of the outer hollow members  46 . By positioning radiant energy reflector  65  on or along a portion of the heat exchanger core  42  adjacent to the burner  30 , radiant heat energy from the combustion flames of the burner is thereby directed toward the room or space to be heated. Radiant energy reflector  65  may also be in the form of a material selection and/or exterior surface treatment of the outer hollow members  46  to provide the desired surface reflective characteristics. 
         [0052]    Each heat exchanger core  42  is constructed and arranged to increase the dwell time of hot combustion gases  37  in the annular passageway  48  thereby increasing the heat transfer between the relatively hotter combustion gases and the relatively cooler heat transfer medium  52 . An object is to extract as much thermal energy as possible in a relatively compact space. By doing so, materials of construction for the chimney flue can be selected having to withstand much lower temperatures, as low as about 150° F. in at least one embodiment, thereby allowing less expensive materials to be used for the chimney flue, such as PVC. To this end, the heat exchanger cores  42  are configured to cause a vortex flow of the combustion gases  37  as they flow through the annular passageway  48 . The vortex flow is caused by at least one nozzle disk  70  ( FIGS. 2A ,  6  and  9 - 10 ), which is connected to at least one of the inner and outer hollow members  44 ,  46  and positioned proximate to the inlet end  86  ( FIG. 6 ) of the annular passageway  48 . As hot combustion gases pass through nozzle disk  70 , the gases are forced to swirl about the annular passageway  48  (e.g.,  FIG. 6 ), generally circulating around the inner hollow member  44  as the gases proceed along the length of the heat exchanger core  42 . Referring to  FIG. 4 , combustion gases  37  flowing downwardly through heat exchanger core  42  rotate generally counterclockwise, when viewed from above, about the inner hollow member  44  as the gases downwardly traverse the annular passageway  48 . While the rotation for the upwardly directed combustion gases is opposite that of the downwardly directed combustion gases  37 , as shown in  FIGS. 4 and 5 , in another embodiment (not shown), the rotational directions of combustion gases  37  are the same in both directions. The direction of spin for at least the downwardly directed combustion gases  37  in the annular passageways  48  is selected to be aided by the Coriolis effect of the earth&#39;s rotation, further enhancing the spinning motion of the combustion gases traversing through the annular passageways. Those skilled in the art will appreciate the direction of spin shown corresponds to the Coriolis effect in the northern hemisphere, so that an installation for use in the southern hemisphere should be configured to cause a spin in a reverse direction. 
         [0053]      FIGS. 9 and 10  show details of the nozzle disk  70 , which disk positioned proximate to the inlet end  86  of each annular passageway  48 . In one embodiment, nozzle disks  70  may be interconnected to each other. In one embodiment, nozzle disk  70  is of generally planar circular construction, having an outer perimeter  72  generally matching the inner perimeter of outer hollow member  46  ( FIG. 4 ), and an inner opening structure  74  through which the inner hollow member  44  ( FIG. 4 ) passes. In one embodiment, inner and outer hollow members  44 ,  46  and nozzle disk  70  are arranged along a common centerline corresponding to the longitudinal axis of the hollow members  44 ,  46 . A plurality of vane structures  76  is arranged generally radially about the centerline. The vane structures include a penetration  73  through the nozzle disk structure and a flow directing vane  75  positioned such that hot combustion gases passing through the penetrations  73  impinge on the flow directing vane and are deflected. Each flow directing vane  75  defines an inclination angle Φ with respect to the plane of the nozzle disk, approximately 30 degrees in one embodiment, but those skilled in the art will recognize that a wide variation in the angle of inclination can be used without deviating from the functional objective of the nozzle disk  70 . Gaps between the inner and outer hollow member  44 ,  46  walls and the nozzle disk  70  are minimized by a tight-fitting interface so that combustion gases bypassing the nozzle disk will be minimized. 
         [0054]    Referring now to  FIGS. 2 ,  2 A,  3 - 6  and  6 A, there is shown one embodiment for circulating heat transfer medium  52 , room air in one embodiment, through the heat exchanger assembly  40  to heat the adjacent space. Once heat transfer medium  52  is heated after passing through heat exchanger assembly  40 , it is designated as heated heat transfer medium  53 . As shown, a supply conduit  80  is employed to convey heat transfer medium  52 , and a return conduit  90  is employed to convey heat transfer medium  53 . 
         [0055]    In operation, a fan/motor assembly  100  draws relatively cool heat transfer medium  52  from the space or room and directs it through supply conduit  80  toward the heating medium inlet opening  84  of the heat exchanger core  42 . To simplify installation and accommodate fireplaces of different size, supply conduit  80  includes several portions that slidingly overlap each other. 
         [0056]    In one embodiment, after being directed through fan/motor assembly  100 , heat transfer medium  52  enters plenum  58  which defines a region of increasing cross-sectional area between the lower and upper end of plenum  58 , as measured by horizontal planes (not shown). In other words, plenum  58  increases in arial transverse directions between the lower and upper end of plenum  58 , as shown orthogonally in  FIGS. 3 and 4 . This increase in cross-sectional area significantly reduces the velocity of entering heat transfer medium  52  without decreasing the energy associated with the fluid flow from fan/motor assembly  100 . In addition, as shown in  FIG. 4 , one or more vanes  83  are disposed within plenum  58  to selectably redirect a portion of the flow of heat transfer medium  52  to at least the outermost positioned heat exchanger cores  42 . Vanes  83  are configured to redirect flow of heat transfer medium  52  to more evenly distribute the amount of the medium flowing through each heat exchanger core  42  while minimizing a reduction of energy associated with the fluid flow from fan/motor assembly  100 . 
         [0057]    After exiting plenum  58 , heat transfer medium  52  enters the interior of inner hollow member  44  through the heating medium inlet opening  84  and moves through the heat exchanger cores  42  while absorbing thermal energy from the hot combustion gases  37  that are spinning around the outer surface of the inner hollow member  44 . After passing through the heat exchanger cores  42 , the heated heat transfer medium  53  ( FIG. 6 ) then exits the heat exchanger assembly  40  through a heating medium outlet opening  94  and is delivered back to the area or room to be heated by the return conduit  90 . 
         [0058]    It is appreciated that as shown in  FIG. 2A , heat exchanger assembly  40  is similarly able to accommodate fireplaces of different height due to the overlapping sliding rectangular portions  79 ,  81  surrounding heat exchanger cores  42 . 
         [0059]    Conduit design may include adjustable and/or flexible supply and return conduit  80 ,  90  to enable plenums to be installed in a variety of fireplace sizes and configurations. While imperative for retrofit installations where the exact fireplace dimensions are unknown when the conduits are fabricated, such flexibility may also benefit purpose-built fireplace installations by enabling a single conduit design to be used on a range of fireplace sizes. Such flexible design streamlines production and inventory requirements, thereby reducing overall cost of production of the invention. 
         [0060]    While the embodiment shown in  FIG. 2  describes use of one embodiment of the disclosure invention for heating a room adjacent to the fireplace, other alternatives are possible by directing the air supply and return conduits to other rooms. Those skilled in the art will recognize that numerous options for directing a heat transfer medium to and through the heat exchanger assembly are permissible within the scope of the present invention. While six generally parallel flow paths are shown in  FIG. 4 , it is possible to direct the heat transfer medium in a serial flow through the entire heat exchanger assembly wherein a single heating medium inlet opening  84  and a single heating medium outlet opening  94  is used. Conversely, more or less than six generally parallel flow paths may also be used since the heat exchanger cores  42  of the present invention are modular in nature. Adjusting the heating medium flow rates and the flow configuration through the heat exchanger cores allows a desired heating medium return temperature to be selected based on the heat input of the burner assembly. 
         [0061]    In an alternate embodiment, a liquid heat transfer medium may be circulated through the inner hollow members whereupon the liquid heat transfer medium absorbs heat energy from the hot combustion gases. The heated liquid may then be easily conveyed to other locations where the heat energy may be extracted to provide heat to a room or another area. An example remote location would be a heat exchanger positioned in the existing heating system for a house whereby the heat energy from the fireplace is efficiently distributed to the entire heated portion of a house or building structure. Such an application provides further benefit to heat pump systems, which require a supplemental heat source when outside air temperatures fall below certain levels. Heat energy from the fireplace can replace expensive electric resistance heating elements often used as supplemental heat sources for heat pumps, potentially lowering energy costs. Due to the modular arrangement of the heat exchanger assembly, a combination of room air from a room adjacent the fireplace and a heat transfer liquid directed to a heat exchanger in a different location may be accommodated, enabling a single fireplace to effectively heat greater portions of a house, thereby further increasing the effectiveness of the fireplace as a supplemental heating source. 
         [0062]    While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.