Patent Publication Number: US-9404669-B2

Title: Application of electric heat coil in fan unit

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. provisional patent application Ser. No. 61/709,751, filed Oct. 4, 2012, the entire contents of which are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     The invention relates generally to a fan coil unit of a heating, ventilation, and air conditioning system, and, more particularly, to an electric heater coil accessory configured for use with a fan coil unit. 
     In a conventional air conditioning system, the condenser of the refrigeration circuit is located exterior to a building. Typically, this system includes a condensing coil, a fan for circulating outdoor ambient air over the condensing coil, and may additionally have a compressor, reversing valves, and various controls. The air conditioning system further includes an indoor unit having an evaporator for transferring heat energy from the indoor air to be conditioned to the refrigerant flowing through the evaporator and a fan for circulating the indoor air in a heat exchange relationship with the evaporator. This type of unit is referred to as a fan coil unit. 
     In conventional fan coil units, especially those used in warmer climates having a reduced heating demand, an auxiliary electric heat coil accessory may be mounted to the fan coil unit. By including an electric heat coil accessory, the air conditioning system can be adapted to provide both cool and warm air to a building. This electric heat coil accessory connects to the discharge end of the fan coil unit and therefore increases the overall height of the fan coil unit. Because many applications have strict size envelopes within which the fan coil unit must fit, inclusion of the additional electric heat coil accessory is not always possible. In addition, the added height of the accessory makes the fan coil unit more difficult to install. 
     BRIEF DESCRIPTION OF THE INVENTION 
     According to another aspect of the invention, an electric heat coil assembly for use adjacent a heat exchanger assembly in a fan coil unit is provided including at least one electric heat coil. A mount plate supports the at least one electric heat coil such that the at least one electric heat coil extends from the mount plate. The mount plate includes an edge configured to connect to the heat exchanger assembly. At least one relay is coupled to the at least one electric heat coil. The at least one relay selectively applies power to the electric heat coil. 
     According to yet another aspect of the invention, a fan coil unit is provided including a housing duct. A fan assembly circulates air through the housing duct. A heat exchanger assembly is arranged with the housing duct. The heat exchanger assembly is in a heat transfer relationship with the air circulating through the housing duct, At least one open space exists adjacent the heat exchanger assembly. An electric heat coil assembly is located within the at least one open space adjacent the heat exchanger assembly. 
     These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which: 
         FIG. 1  is a front view of an exemplary fan coil unit; 
         FIG. 2  is a side view of the exemplary fan coil unit shown in  FIG. 1 ; 
         FIG. 3  is a perspective view of a fan coil unit in accordance with an embodiment of the invention; 
         FIG. 4  is a perspective view of an electric heat coil assembly in accordance with an embodiment of the invention; 
         FIG. 5  is a perspective view of an alternate fan coil unit in accordance with an embodiment of the invention; and 
         FIG. 6  is a perspective view of an alternate fan coil unit in accordance with an embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to FIGS,  1  and  2 , heating and cooling systems include a ducted fan coil unit  20  having a fan assembly  40  and a heat exchanger assembly  30  disposed inside a housing duct  22 . Depending on the desired unit characteristics, the fan assembly  40  may be positioned either downstream with respect to the coil assembly  30  (i.e. a “draw through” configuration), or upstream with respect to the coil assembly  30  (i.e. a “blow through” configuration) as shown in  FIGS. 1 and 2 . The housing duct  22  includes a lower duct connector  24  and an upper duct connector  26  that define inlet and outlet openings. 
     In the illustrated embodiment, the fan assembly  40  is mounted near the inlet  24  of the unit  20 . The fan assembly  40  includes a fan scroll  44  coordinated with a fan mounted to a fan shaft  42  and is configured to circulate air generally forwardly into the heat exchanger assembly  30 . A combination fan deck and condensate pan  48  extends across the unit  20  located at the same height as the discharge end  46  of the fan scroll  44 . The combination fan deck and condensate pan  48  collects condensate dripping from the surface of the heat exchanger assembly  30  and prevents air discharged from the fan assembly  40  from circulating back to the fan inlet  47 . The heat exchanger assembly  30 , in the illustrated embodiment, has a generally flat profile and is arranged at an angle with respect to the flow path of air through the housing duct  22 . Alternative heat exchanger assemblies  30  are generally V-shaped and generally A-shaped as is known in the art (see  FIGS. 5 and 6 ). The fan assembly  40  directs air into the heat exchanger assembly  30  to either heat or cool the air. The heat exchanger assembly  30  includes a large surface area exposed to the flow path of the air to optimize heat transfer with the air flowing there through. 
       FIG. 2  is a side view of the fan coil unit  20  illustrated in  FIG. 1 , The discharge end  46  of the fan scroll  44  is shown extending through a portion of the combination deck and condensate pan  48 . Hence, it may be seen that the discharge end  46  of the fan scroll  44  is utilized to direct the air being circulated by the fan upwardly through the heat exchanger assembly  30  and out the unit  20  at the upper duct connector  26 . Although a particular fan coil unit  20  configuration is illustrated and described in the disclosed embodiment, other configurations are within the scope of the present invention. 
     Referring now to  FIG. 3 , a fan coil unit  20  according to one embodiment of the present invention is illustrated. The illustrated fan coil unit  20  includes an electric heat coil assembly  60  positioned in an open area  54  between the heat exchanger assembly  30  and the housing duct  22 . The contour of the electric heat coil assembly  60  may be complementary to the shape of the open area  54  between the heat exchanger assembly  30  and the housing duct  22 . For example, a portion of the electric heat coil assembly  60  may be arranged at an angle equal to the angle at which the heat exchanger assembly  30  is positioned relative to the air flow path in the housing duct  22 . In one embodiment, the electric heat coil assembly  60  is generally triangular in shape. Regardless of whether the fan coil unit  20  has a “draw through” configuration or a “blow through” configuration, the electric heat coil assembly  60  may be positioned adjacent the discharge side  34  of the heat exchanger assembly  30  in open space  54 , Air exiting the discharge side  34  of the heat exchanger assembly  30  is therefore heated by the electric heat coil assembly  60  before being circulated into a duct (not shown) connected to the outlet side  26  of the housing duct  22 , such as a duct leading into a portion of a building to be heated for example. Alternatively, the electric heat coil assembly  60  may be positioned in the open space  56  adjacent the inlet side  36  of the heat exchanger assembly  30 . 
     An electric heat coil assembly  60  according to an embodiment of the invention is illustrated in  FIG. 4 . The electric heat coil assembly  60  includes at least one electric heat coil  70  connected to a mounting plate  62 . In one embodiment, the electric heat coil assembly  60  includes a plurality of bunched electric heat coils  70  extending from the mounting plate  62 . The electric heat coils  70  may extend perpendicularly or at an angle to the mounting plate  62 . Each of the plurality of electric heat coils  70  may be generally equal in length or alternatively, the electric heat coils  70  may vary in length. At least one switching device  68 , such as a relay for example, is coupled to the electric heat coils  70  through the mounting plate  62 . The switching device  68  selectively applies power to the electric heat coils  70  to heat air flowing through the coils  70 . The mounting plate  62  is substantially flat and may be formed, for example, from a piece of sheet metal. In one embodiment, at least one edge  64  of the mounting plate  62  is configured to connect to a portion of the heat exchanger assembly  30 . By joining the edge  64  of the mounting plate  62  to the heat exchanger assembly  30 , the plurality of electric heat coils  70  are supported in a position near the heat exchanger assembly  30 . 
     Referring now to  FIG. 5 , another fan coil unit  120  according to an embodiment of the present invention is shown. The heat exchanger assembly  130  of the illustrated fan coil unit  120  includes multiple portions such that multiple open spaces exist between the heat exchanger assembly  130  and the housing duct  122 . The illustrated heat exchanger assembly  130  includes a substantially symmetrical first portion  132  and second portion  138 . A first open space  154  is formed between the first portion  132  and the housing duct  122  and a second open space  156  is formed between the second portion  138  and the housing duct  122 . In addition, a third open space  158  exists between the first portion  132  and the second portion  138  of the heat exchanger assembly  130 . The heat exchanger assembly  130  shown in  FIG. 5  is a generally A-shaped and is commonly referred to as an “A-coil”. 
     In one embodiment, at least one electric heat coil assembly  160  is mounted in one of the open areas  154 ,  156 ,  158  adjacent the A-coil  130 . As illustrated, a first electric heat coil assembly  160  is mounted in the open area  154  adjacent the discharge surface  134  of the first portion  132  and a second electric heat coil  160 ′ is mounted in the open area  156  adjacent the discharge surface  140  of the second portion  138  of the heat exchanger assembly  130 . The first electric heat coil assembly  160  and the second electric heat coil assembly  160 ′ may be substantially symmetrical to one another. Alternatively, the first electric heat coil assembly  160  and the second electric heat coil assembly  160 ′ may have different shapes, sizes, number and arrangements of electric heat coils  170 . 
     The heat exchanger assembly  230  of the fan coil unit  220  illustrated in  FIG. 6 , similarly includes a first portion  232  and a second portion  238 , such that a first open space  254  and a second open space  256  exist between the heat exchanger assembly  230  and the housing duct  222  and a third open space  258  exists between the first and second portions  232 ,  238  of the heat exchanger assembly  230 . The heat exchanger assembly  230  is generally V-shaped and is commonly referred to as a “V-coil”. The V-coil heat exchanger assembly  230  is substantially similar to the A-coil heat exchanger assembly  130  shown in  FIG. 5 , but is inverted within the housing duct  222  such that the first portion  232  and the second portion  238  are joined adjacent the inlet end  224  of the housing duct  222 , 
     At least one electric heat coil assembly  260  is mounted in one of the open areas  254 ,  256 ,  258  adjacent the V-coil  230 . In one embodiment, at least one electric heat coil assembly  260  is positioned within the open area  258  between the first portion  232  and the second portion  238  of the heat exchanger assembly  230 . As illustrated, a single electric heat coil assembly  260  may be configured to fit within open space  258  adjacent the discharge surfaces  234 ,  240  of the heat exchanger assembly  230 . However, multiple electric heat coil assemblies  260  may be configured to fit within an open space, such as open space  258  for example. If multiple electric heat coil assemblies  260  are located within an open space, the electric heat coil assemblies  260  may be substantially uniform in size and shape. Alternatively, the multiple electric heat coil assemblies  260  within an open space may be distinct sizes and shapes that fit within the open space. 
     By including at least one electric heat coil assembly within the open spaces, of the housing duct, the overall height of the fan coil unit is reduced, such as by a distance of approximately eight to ten inches, This reduction in height allows for greater flexibility during installation of the fan coil unit. 
     While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.