Patent Publication Number: US-6700098-B1

Title: System for preventing and clearing ice dams

Description:
BACKGROUND OF THE INVENTION 
     This invention relates generally to deicing systems and, more particularly, to a system for preventing and clearing ice dams from roof gutters and downspouts. 
     Ice and snow on the roof of a house or building melts as heat from the building warms the roof. Water from the melting ice and snow then runs to the edges or “eaves” of the roof and into a gutter or eave trough where it tends to refreeze. This refrozen water forms an ice dam at the roof edge or in the gutter which can be damaging to the house or building structure in that additional water from melting snow may pool up and seep through the roof into the house, causing damage to drywall, insulation, etc. Further, additional water may contribute to increasing the size and weight of the ice dam. 
     Various deicing systems have been proposed in the art for clearing ice and snow from gutters mounted to a roof edge. Although assumably effective for their intended purposes, the existing systems do not provide for selective placement of a heating cable on a roof surface itself as well as in a gutter and associated downspouts. Further, the existing systems do not provide convenient user controls that improve utility and energy conservation. 
     Therefore, it is desirable to have a system for preventing and clearing ice dams for use with gutters and downspouts that includes rotatable, pivotal, and telescopic heat cable holding assemblies. Further, it is desirable to have a system that utilizes a self-regulating heat cable having a plurality of sections that respond independently to changes in ambient temperature. In addition, it is desirable to have a system having multiple modes of operation for optimal user control of the system. 
     SUMMARY OF THE INVENTION 
     An ice dam prevention and clearing system for use with gutters and downspouts mounted to a roof includes a plurality of wire holding assemblies, each assembly having a base for attachment to a gutter panel and an elongate arm coupled to the base. The system further includes a heating cable for generating beat when electrically actuated. Each assembly arm includes at least one fastener for retaining the heating cable. Each arm is rotatably and pivotally coupled to a respective base such that the arm may be laterally positioned on a roof surface adjacent a gutter or completely displaced from the roof surface. In addition, each arm is length adjustable such that the heating cable may be vertically extended along the roof surface. The heating cable may also be positioned in the gutter itself. Therefore, this system may heat a roof surface adjacent a gutter so as to prevent the formation of an ice dam or to eliminate an existing ice dam so that the melted water may flow through the gutter. The heating cable is connected to a control unit that includes a selector switch for selecting a mode of operation. 
     Therefore, a general object of this invention is to provide a system for the prevention and clearing of an ice dam in or adjacent a gutter mounted to the edge of a roof. 
     Another object of this invention is to provide an ice dam prevention and clearing system, as aforesaid, which includes a plurality of wire holding assemblies that may be spaced apart along a gutter for holding a heating cable. 
     Still another object of this invention is to provide an ice dam prevention and clearing system, as aforesaid, in which an arm of each wire holding assembly is pivotally and rotatably coupled to a base for positioning the arm at a desired position relative to a roof surface. 
     Yet another object of this invention is to provide an ice dam prevention and clearing system, as aforesaid, in which the arm of each wire holding assembly is telescopically length adjustable. 
     A further object of this invention is to provide an ice dam prevention and clearing system, as aforesaid, that provides a plurality of user-selectable modes for operation of the system. 
     A still further object of this invention is to provide an ice dam prevention and clearing system, as aforesaid, including temperature and moisture sensors for determining when the heating cable is energized. 
    
    
     Other objects and advantages of this invention will become apparent from the following description taken in connection with the accompanying drawings, wherein is set forth by way of illustration and example, an embodiment of this invention. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a ice dam prevention and clearing system according to a preferred embodiment of the present invention in use with a gutter and associated downspouts; 
     FIG. 2 is a fragmentary perspective view of the system as in FIG. 1 showing the control unit on an enlarged scale; 
     FIG. 3 is a fragmentary perspective view of the system as in FIG. 1 showing a wire holding assembly and heating cable on an enlarged scale; 
     FIG. 4 is a fragmentary perspective view of the system as in FIG. 1 on an enlarged scale and taken from another angle; 
     FIG. 5 is a fragmentary perspective view on an enlarged scale of an end of a downspout as in FIG. 1; 
     FIG. 6 is a perspective view of a plurality of wire holding assemblies as in FIG. 1 with an arm of one of the assemblies in a configuration displaced from a roof surface; 
     FIG. 7 is a perspective view of a wire holding assembly as in FIG. 1 on an enlarged scale and removed from attachment to a gutter; 
     FIG. 8 is an exploded view of the wire holding assembly as in FIG. 7; 
     FIG. 9 is front view on an enlarged scale of the control panel of the control unit as in FIG. 1; 
     FIG. 10 a  is a block diagram of the electrical components of the preferred embodiment of the ice dam prevention and clearing system; 
     FIG. 10 b  is a block diagram illustrating the modes of operation implemented by system central processing unit (CPU); 
     FIG. 11 is a flowchart illustrating the program logic implemented by the CPU according to one mode of operation; and 
     FIG. 12 is a flowchart illustrating the program logic implemented by the CPU according to another mode of operation. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     An ice dam prevention and clearing system  10  according to the preferred embodiment will now be described in detail with reference to FIGS. 1 through 12 of the accompanying drawings. The system may be installed for use with gutters  2  attached to edges of a roof  6  (FIG.  1 ). 
     The system  10  includes a plurality of wire holding assemblies, each holding assembly  12  having a base  14  and an elongate arm  16  coupled to the base  14  (FIG.  7 ). More particularly, the base  14  includes a generally inverted U-shaped configuration and is constructed of spring steel or aluminum although a durable plastic construction would also be suitable. Lower edges of the base  14  are biased toward one another such that the base  14  may be frictionally attached to the elongate front wall of a gutter  2 . The arm  16  of each wire holding assembly  12  includes a mounting shaft  18  that is rotatably coupled to the base  14  (FIGS.  7  and  8 ). The mounting shaft  18  establishes an imaginary vertical axis about which the entire arm  16  may rotate, thus allowing the arm  16  to be positioned laterally along a roof surface (FIG.  1 ). Further, the arm  16  includes a spring-loaded coupling  20  for pivotally mounting the arm  16  to the mounting shaft  18  which, in turn, is coupled to the base  14 . This spring-loaded coupling  20  includes a spring  22  and a bolt  24 , pin, or the like (FIG. 8) such that the arm  16  is pivotally movable about an imaginary horizontal axis of the bolt  24 , the arm  16  being movable between a first configuration in contact with a roof surface  6  (FIG. 3) and a second configuration displaced from the roof surface (FIG.  6 ). 
     Each arm  16  includes a plurality of telescopic sections  26  such that the arm is length-adjustable. A first telescopic section is connected to the mounting shaft  18  that, in turn, is rotatably coupled to the base  14 . Further, a plurality of wire fasteners  28  is mounted to the arm  16  (FIG. 7) although each arm may include only a single fastener  28 . 
     The system  10  includes a self-regulating heating cable  30  for generating heat when electrically energized, as to be described in more detail below. Preferably, the heating cable  30  is a conductive polymeric temperature coefficient of resistance (PTCR) cable having a polymeric core with embedded graphite. The PTCR cable includes a plurality of sections, each of which responds independently to changes in ambient temperature. When energized, the PTCR cable produces an amount of heat for melting ice and snow with which it is in contact. The amount of heat is dependent upon the ambient temperature surrounding the cable. The polymeric formulation of the PTCR cable causes the amount of heat output produced by the cable to vary in an inversely proportionate relationship to changes in temperature. In other words, the heat output increases when the ambient air is colder and decreases when warmer. Specifically, as the core temperature increases, the number of conductive paths in the core material decreases, automatically decreasing heat output. This inverse relationship has the effect of saving energy as temperature increases. The heating cable  30  may be retained by the fasteners  28  of each wire holding assembly  12  for covering a substantial portion of a roof surface  6  adjacent a gutter  2 . The heating cable  30  may also be positioned in the gutter  2  itself and may even be extended through associated downspouts  4  (FIGS.  1 - 5 ). 
     The system  10  further includes a control unit  32  (also referred to as a control box) for connection to a conventional electrical power source such an AC wall outlet  38  (FIG.  1 ). The control unit  32  includes a central processing unit (CPU) for controlling system operations and mode selections, as to be described more fully below. The heating cable  30  is electrically connected to the control unit  32  (FIG. 5) for control by the CPU. The system  10  also includes sensors for determining if conditions are suitable for activation of the heating cable  30 . More particularly, the system may include a moisture sensor  40 , a precipitation sensor  42 , an eave temperature sensor  44 , a roof temperature sensor  46 , and an ambient air temperature sensor  48  (FIG. 10 a ). While all of these sensors may be directly connected to the CPU with electrical wires in a conventional manner, it would also be suitable for the sensors to communicate remotely with the CPU, such as through radio frequency transmission or the like. In either case, the sensors deliver respective data signals to the CPU. The sensors are generally positioned adjacent the heating cable  30 . 
     The control unit  32  includes a control panel  34  having a selector switch  36 . The selector switch  36  is pivotally movable between “Auto”, “Manual”, and “Timer” configurations (FIG.  9 ). More particularly, there are two “Auto” mode selection options. The selector switch configurations correspond to CPU-controlled modes as shown in FIG. 10 b . When the “manual” mode  50  is selected, the CPU immediately energizes the heating cable  30  until the mode is changed or electrical power is otherwise interrupted. Operation of a first automatic mode  54  is illustrated in FIG.  11 . The heating cable  30  is only energized  68  when the moisture sensor  40  indicates the presence of moisture  62  and when the eave temperature sensor  44  indicates a temperature less than a predetermined temperature  64 , e.g. 32° F., and the roof temperature sensor  46  indicates a temperature greater than a predetermined temperature  66 , e.g. 32° F. In other words, the heating cable  30  is energized only when all three conditions are present: moisture is present, melting is occurring on the roof surface  6 , and freezing is occurring at the eave/gutter  2 . 
     Operation of a second automatic mode  56  is illustrated in FIG.  12 . In this mode, the CPU energizes the heating cable  30  as indicated by reference numeral  76  when the precipitation sensor  42  indicates that precipitation is actively falling  72  and the ambient temperature sensor  48  indicates a temperature below a predetermined temperature  74 , e.g. 35° F. It is understood that the ambient temperature threshold in this mode is greater than 32° F. as snow can fall at temperatures above 32° F. It is also understood that the precipitation sensor  42  may be vertically oriented to collect and sense falling precipitation and may be self-cleaning with a heating element to evaporate collected precipitation. 
     The control unit  32  further includes conventional timer circuitry connected to the CPU. As shown in FIGS. 11 and 12, the actuation of the heating cable  30  may be made subject to this timer function. With particular reference to FIG. 11, if the heating cable has been activated  68  but precipitation is not actively falling  80 , then the a timer is activated  82  for a predetermined period of time so as to clear any ice dam and then the heating cable  30  is deactivated. Primed reference numerals are utilized in FIG. 12 for this same function. 
     In addition, a user may select the timer mode  52  to have greater control over how long the heating cable  30  is energized. In the timer mode, a user may select a duration and the remaining time will be displayed on a display screen  37  of the control panel  34 . The CPU operates to deactivate the heating cable  30  upon expiration of the selected time. 
     In use, the ice dam prevention and clearing system  10  may be installed before or after an ice or snow event. In either case, the plurality of wire holding assemblies may be removably attached in longitudinally spaced apart relation along a gutter connected to the edge of a roof surface (FIG.  1 ). The arm  16  of each assembly  12  may be telescopically length adjusted and may be rotatably oriented in desired lateral positions. The heating cable  30  may be held in place along the arms  16  with the arm fasteners  28 . The heating cable  30  may also be positioned in the gutter  2  itself as well as in associated downspouts  4 . A user may then select a desired mode of operation using the control panel  34  of the control unit  32 . In either of the automatic modes, the CPU evaluates data signals from respective sensors and then actuates the heating cable  30  when predetermined parameters are met. A user may exercise even more control over heating cable activation by selecting the manual or timer mode. 
     It is understood that while certain forms of this invention have been illustrated and described, it is not limited thereto except insofar as such limitations are included in the following claims and allowable functional equivalents thereof.