Abstract:
A power distribution system for an air handler is reconfigureable by way of selectively connectable plug-in connectors. The air handler includes a blower associated with a first plug-in connector that is selectively connectable to a second plug-in connector of a heater and a third plug-in connector of an electric air cleaner. If the air handler includes a heater but not the electric air cleaner, then the blower connector plugs into the heater connector. If the air handler includes an electric air cleaner but not a heater, then the blower plugs into the connector of the air cleaner. And if the air handler includes both a heater and an electric air cleaner, then a three-way electrical connector couples the blower to both the heater and the air cleaner.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The subject invention generally pertains to an air handler and more specifically to an air handler connected to a reconfigureable electrical distribution system. 
     2. Description of Related Art 
     Air handlers typically condition the air of a comfort zone, such as a room or area within a building, and can assume a variety of configurations. Many air handlers include a fan or blower to move the air across a heat exchanger, such as an evaporator or condenser of a heat pump or some other refrigeration system. They can also include a variety of other components or accessories, such as an electrostatic air cleaner and/or supplemental electric heaters. Unfortunately, the variety of configurations can create a problem for an electrician installing the equipment. 
     For example, when an electrostatic air cleaner is to be added to an air handler having an electric heater, a 115 or 230-volt outlet may not be available for the air cleaner. Since installing such an outlet adds to the time and cost of the air cleaner&#39;s installation, an electrician may consider wiring the air cleaner in parallel with the 115 or 230-volt electric heater. However, such an approach often violates national and local electrical codes, as the current draw of a heater is usually much higher than that of an air cleaner. Consequently, an air cleaner&#39;s lighter gage wiring may be inadequately protected against current overload (e.g., a short circuit) when it is connected in parallel with a heater&#39;s heavier gage wiring. This is especially true when the heavier wiring is protected by a circuit breaker that is appropriate for the heavier wiring but oversized for the lighter wiring. 
     SUMMARY OF THE INVENTION 
     To facilitate the installation of air handlers of various configurations, it is an object of the invention to provide a power distribution system that is reconfigureable by way of selectively connectable plug-in connectors. 
     Another object of the invention is to safely connect lighter gage wiring of an air handler accessory in parallel with an electric heater having heavier gage wiring. 
     Another object is to provide a three-way electrical connector that reconfigures an air handler to accept various accessories. 
     Yet another object is to provide a reconfigureable plug-in connector that conveys both control voltage and higher power voltage. 
     A further object of the invention is to effectively protect both lighter and heavier gage wiring with a common circuit breaker. 
     A still further object is to avoid the time and cost of installing an additional electrical outlet dedicated to power an accessory of an air handler. 
     These and other objects of the invention are provided by an air handler that includes a blower associated with a first plug-in connector that is selectively connectable to a second plug-in connector of a heater and a third plug-in connector of an electric accessory to selectively reconfigure the air handler. 
    
    
     BRIEF DESCRIPTIONS OF THE DRAWINGS 
     FIG. 1 is a wiring schematic of an embodiment of the invention showing an air handler in one configuration. 
     FIG. 2 is a wiring schematic of an embodiment of the invention showing an air handler in a second configuration. 
     FIG. 3 is a wiring schematic of an embodiment of the invention showing an air handler in a third configuration. 
     FIG. 4 is a wiring schematic of an embodiment of the invention showing an air handler in a fourth configuration. 
     FIG. 5 is a wiring schematic of an embodiment of the invention showing an air handler in a fifth configuration. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     An air handler, schematically illustrated in FIG. 1, includes a three-way connector  10  that electrically interconnects a blower  12 , a heater assembly  14 , an electric air cleaner  16 , and an electrical panel  18 . Blower  12  draws return air from a comfort zone and through cleaner  16  that electrostatically removes dust and other airborne particles. Blower  12  discharges the air across one or more heaters, such as heaters  20 ,  22  and  24 , to provide heated supply air to the comfort zone when needed. Arrows  26  denote the general direction of airflow. Typically the blower  12  and the heater assembly  14  share a common housing  25 . The air cleaner  16  is preferably connected upstream of the housing  25  so that air flows through the air cleaner  16  into the blower  12 , and across the heaters  20 ,  22 ,  24 . In some embodiments, the air handler also includes a refrigeration system, such as a heat pump that also conditions the temperature and/or humidity of the comfort zone. In such embodiments, the heat pump provides the primary cooling or heating, while heaters  20 ,  22  and  24  supplement heating as needed. In response to sensing the temperature and/or humidity of the comfort zone, a conventional thermostat  28  controls the operation of heater assembly  14  and blower  12 , and may further control the operation of the heat pump, if present. 
     In the embodiment of FIG. 1, an electrical supply  30  (e.g., power voltage of 230 VAC) is applied across supply leads  32  and  34  to power the air handler. Two current interrupters  36  (e.g., a 30-amp circuit breaker or fuse), a set of normally open relay contacts  38  and a normally closed temperature limit switch  40  are connected electrically in series with heater  20 . This allows electrical supply  30  to energize heater  20  when contacts  38  and limit switch  40  are closed. Under normal operation, temperature limit switch  40  remains closed and only opens upon sensing an abnormally high temperature brought on by, for example, insufficient airflow across heater  20 . A relatively heavy wire  42  (e.g., 12-gage wire) provides the series connection of the heater-related components. Similarly, two more current interrupters  44  (e.g., 60-amp circuit breaker or fuse), a set of normally open relay contacts  46  and a normally closed temperature limit switch  48  (similar or identical to switch  40 ) are connected electrically in series with heater  22 . Supply  30  energizes heater  22  when contacts  46  and limit switch  48  are closed. Interconnecting wire  50  is similar to that of wire  42 . A set of relay contacts  52  and a temperature limit switch  54  (similar or identical to switch  40 ) couple heater  24  electrically in parallel with heater  22  and in series with breakers  44 . Thus, breakers  36  protect wiring  42 , while breakers  44  protect wiring  50  and also protect interconnecting 12-gage wire  56  associated with heater  24 . Electrical power leads  58  and  60  are wired to a plug-in connector  62  (e.g., a socket 19-09-2061 w/02-09-2101 by Molex of Lisle, Ill.). An additional three leads  64 ,  66  and  68  connect socket  62  to a 24-volt (control voltage) relay coil  70  associated with contacts  38  and  46 , and a similar relay coil  72  associated with contacts  52 . 
     Three-way connector  10 , comprising plug-in connectors  74 ,  76  and  78 , plugs into socket  62  by way of connector  74  (e.g., a Molex plug 19-09-1061 w/02-09-1102). Connectors  62  and  74  connect power voltage leads  58  and  60  to air cleaner  16  by way of wires  80 , a connector  78  (e.g., a Molex plug 19-09-1061 w/02-09-1102), a mating plug-in connector  82  (e.g., a Molex socket 19-09-2061 w/02-09-2101), wires  84 , wire nuts  86 , and an air cleaner power cord  88 . Connectors  62  and  74  also connect leads  60 ,  58 ,  64 ,  66  and  68  to wires  90 ,  92 ,  94 ,  96  and  98  respectively by way of wires  100 , a plug-in connector  76  (e.g., a Molex socket 19-09-2061 w/02-09-2101), and a mating plug-in connector  102  (e.g., a Molex plug 19-09-1061 w/02-09-1102). In this embodiment, wires  90 ,  92 ,  94 ,  96  and  98  feed into panel  18 . 
     Within panel  18 , wires  90  and  92  apply power voltage to the primary windings of a transformer  104  to provide 24 VAC control voltage across wire  94  and a wire  106 . Wire  106  conveys the control voltage onto thermostat  28 . Since there are a wide variety of thermostats know to those skilled in the art, thermostat  28  is schematically illustrated to include a blower switch  108  and two temperature switches  110  and  112 , all of which receive control voltage from wire  106 . Switches  110  and  112  both close in response to the temperature of the comfort zone dropping to a set point, but each at a slightly different set point. Blower switch  108  closes in response to a demand for airflow, e.g., whenever switch  110  or  112  calls for heat. Blower switch  108  closing energizes a coil  114  of a blower relay  116  to close its contacts  118  and  120 . Contacts  120  energize blower  112 , while contacts  118  enable switches  110  and  112  to energize their respective coils  72  and  70 . Switch  110  closing energizes coil  72  through leads  64  and  68  to actuate contacts  52 , which turns on heater  24 . Switch  112  closing energizes coil  70  through leads  64  and  66  to actuate contacts  38  and  46 . Contacts  38  and  46  turn on heaters  20  and  22  respectively. 
     In many cases, wiring a low wattage component with light gage wire in parallel with a higher wattage component having heavier gage wire is considered poor wiring practice and often violates electrical codes. However, a unique opportunity presents itself with an air handler having several high-wattage heaters and a low wattage air cleaner connected as shown in FIG.  1 . For air handlers, some electrical codes restrict the maximum allowable current draw of heaters to about 48 amps when the heater wiring is protected by just one pair of circuit breakers. For heat requirements above 48 amps, multiple heaters are wired in parallel to each other to create several parallel circuits each wired with, for example, 12-gage wiring (to conduct up to 48 amps). And each parallel circuit can be protected by a pair of standard-sized 30-amp or 60-amp breakers, depending on the size of the heater or heaters. However, 18-gage wiring can also readily trip a 60-amp breaker. Thus, lighter 18-gage wire can safely connect an appropriately sized, relatively low wattage air cleaner in parallel with a heater, provided the air cleaner is wired in series with one pair of breakers that protects the heater&#39;s heavier gage wiring. For example, one pair of breakers can protect both the 12-gage wire leading to a heater and a lighter 18-gage wire feeding an air cleaner. 
     For the exemplary embodiment of FIG. 1, air cleaner power cord  88  is 16-gage wiring that electrically connects air cleaner  16  in parallel with heater  24  and in series with breakers  44 . Heaters  20 ,  22  and  24  each draw about twenty amps, and breaker  44  is rated at sixty amps. Thus, breaker  44  protects the 12-gage wiring  50  and  56  of respective heaters  22  and  24  as well protects the 16-gage wiring of power cord  88 . 
     The air handler of FIG. 1 can also be reconfigured as shown in FIG.  2 . When air cleaner  16  is omitted, blower connector  102  plugs directly into heater socket  62 , and the three-way connector  10  and the air cleaner power cord  88  are not required. Socket  82  and wires  84  can be removed or left unused as shown. The operation of blower  12 , heater assembly  14  and thermostat  88  remains basically the same as that of the configuration of FIG.  1 . 
     In another configuration, shown in FIG. 3, the air handler includes air cleaner  16  but does not include heater assembly  14 . In this example, blower connector  102  plugs directly into socket  82 , and electrical supply  30  delivers power voltage directly to the air cleaner power cord  88  and wires  84  at wire nuts  86 . Wires  84  deliver the power voltage to wires  90  and  92  to energize blower  12  and transformer  104 . 
     In yet another configuration, shown in FIG. 4, the air handler has neither heater assembly  14  nor air cleaner  16 . Here, blower connector  102  plugs directly into socket  82 , and electrical supply  30  delivers power voltage to blower  12  and transformer  104  by way of wires  84 , connectors  82  and  102 , and wires  90  and  92 . 
     The embodiment of FIG. 5 is similar to that of FIG. 3; however, wire nuts  86  are eliminated by combining wires  84  and  88  (FIG. 3) to create a continuous power cord  88 ′ that directly couples air cleaner  16  to socket  82 . To power air cleaner  16  and blower  12 , power supply  30  is connected to socket  62 , which, in turn, is coupled to air cleaner socket  82  and blower plug  102  by way of three-way connector  10 . 
     Although the invention is described with respect to a preferred embodiment, various modifications thereto will be apparent to those skilled in the art. For example, plugs  74 ,  78  and  102  could be sockets when sockets  62 ,  76  and  82  are plugs. Therefore, the scope of the invention is to be determined by reference to the claims, which follow.