HEATING ASSEMBLY AND METHOD FOR FREEZE PROTECTION OF HOLLOW DOCK SUPPORT LEGS

[0001] This application claims priority to U.S. Provisional Patent Application No. 63/743,715, filed January 10, 2025, entitled “Energy-Efficient Heating Assembly for Dock Support Legs to Mitigate Freezing Damage,” the disclosure of which is incorporated by reference herein in its entirety.

[0002] The present disclosure relates to freeze protection and ice mitigation for stationary dock structures, and more particularly to heating assemblies configured to heat a hollow dock support leg and/or fluid within the hollow dock support leg to mitigate freezing-related damage and external ice loading.

[0003] In cold climates, stationary docks and similar waterfront structures may be subjected to freezing and ice movement that can damage support legs, pilings, and dock frames. Hollow dock support legs—often formed from aluminum, steel, galvanized steel, composite, polymer, or other materials—may become partially or fully filled with water from the surrounding body of water when open at a lower end.

[0004] Freezing within the hollow interior of the dock support leg can cause damage due to ice expansion and can contribute to deformation, cracking, splitting, or displacement of the leg and the overall dock structure. Additionally, freezing around the outer surface of the dock support leg can increase adhesion between the leg and the surrounding ice, thereby increasing lateral and torsional loads on the dock structure as ice shifts.

[0005] Conventional approaches, such as bubblers and dock de-icers, circulate or aerate water near the water surface to reduce ice formation. Such systems may be energy intensive, may create hazardous open water conditions, and may disturb aquatic habitats by disrupting natural ice coverage or sediment. Other known approaches include heating elements disposed around a piling within a sleeve or hose to heat an annular water space; however, such systems are not optimized for preventing freezing within a hollow dock support leg and may be cumbersome to install and maintain.

[0006] Accordingly, there is a need for a safe, energy-efficient, and modular heating assembly to inhibit freezing within hollow dock support legs and to reduce external ice adhesion and loading, while avoiding hazardous open-water conditions.

[0007] Disclosed herein is a heating assembly for a stationary dock structure. The heating assembly includes a heating element (C) configured to be disposed within an interior cavity of a hollow dock support leg (L). During operation, the heating element heats at least one of (i) a fluid within the interior cavity and (ii) a wall of the hollow dock support leg, thereby inhibiting freezing within the interior cavity and reducing ice adhesion and loading external to the dock support leg.

[0008] In some embodiments, the heating element comprises a self-regulating positive temperature coefficient (PTC) heating cable. In other embodiments, the heating element may comprise a constant-wattage heating cable, resistive heater, cartridge heater, immersion heater, or other heating device.

[0009] A retainer, such as a strain-relief grommet (12) and/or one or more grommets (F), may be positioned at an opening of the hollow dock support leg to retain the heating element and to protect the heating element from abrasion. The retainer may be adjustable along a length of the heating element to set a selected insertion depth into the hollow dock support leg. In some embodiments, the heating element is provided in a standardized length (e.g., about 48 inches), and the retainer is repositionable to accommodate dock support legs of differing lengths.

[0010] The heating assembly may include one or more waterproof electrical connections (1,2) configured to couple the heating element to a power supply (S). In one embodiment, the electrical connections include an IP67-rated connector such as a threaded M14 connector. In some embodiments, a ground fault circuit interrupter (GFCI) device is included as part of the heating assembly or kit.

[0011] The heating assembly may be installed by forming an opening in an upper region of the dock support leg and inserting the heating element into the interior cavity, or by inserting the heating element through an open upper end of the dock support leg.

[0012] Multiple heating assemblies may be combined to heat multiple dock support legs of a dock structure. Such assemblies may be physically daisy-chained while being electrically coupled in parallel, and may alternatively be coupled in parallel via a trunk-line distribution arrangement or in series.

[0016] The invention relates to a heating assembly configured for installation in hollow dock support legs (L) of stationary docks. The heating assembly includes a heating element (C) disposed within an interior cavity of the hollow dock support leg and configured to inhibit freezing within the cavity, thereby reducing damage caused by internal ice expansion and reducing external ice adhesion and loading.

[0017] Dock support legs (L) may be cylindrical, square, or otherwise shaped, and may have a diameter or width from about 1 inch to about 12 inches, and more typically from about 2 inches to about 4 inches. Dock support legs may be formed from aluminum, steel, galvanized steel, polymer, composite, or other materials having sufficient structural integrity to support a dock structure and sufficient thermal conductivity to transfer heat from the heating element to the surrounding environment.

[0018] In one embodiment, the dock support legs are open at a lower end such that water from the surrounding body of water enters and fills the interior cavity to a fluid level. In another embodiment, the dock support legs are sealed and contain a fluid such as water, brine, antifreeze solution, oil, or other suitable fluid. In another embodiment, the interior cavity contains air or is substantially air-filled, and the heating element heats a wall of the dock support leg to inhibit freezing and reduce external ice adhesion.

[0019] The heating element (C) may comprise a self-regulating PTC heating cable that adjusts power output based on temperature. In other embodiments, the heating element may comprise a constant-wattage heat trace cable, resistive heating element, cartridge heater, immersion heater, or other heater. The heating element may be encased in a waterproof, submersible sheath formed from polyolefin, fluoropolymer, or other durable materials to resist water ingress and environmental wear.

[0020] In some embodiments, the heating element provides approximately 6 to 9 watts per linear foot under cold conditions, although power may vary with ambient temperature, installation geometry, and self-regulating characteristics.

[0021] In some embodiments, the heating element (C) is supported at an opening of the dock support leg by a strain-relief grommet (F). The strain-relief grommet may provide frictional retention to prevent the heating element from slipping into the cavity. The grommet may be adjustable along the heating element to set a selected insertion depth, such that an installer may position the grommet at a desired point along the heating element and insert a corresponding portion of the heating element into the dock support leg.

[0022] In some embodiments, the heating element is provided in a standardized length (e.g., about 48 inches), and the adjustable grommet enables a single heater length to be configured for dock support legs of differing heights and water depths.

[0023] One or more additional grommets (F) may be provided to protect the heating element from abrasion at contact points, to guide the heating element into the cavity, or to provide additional retention.

[0024] In some embodiments, at least a portion of the heating element is disposed below a fluid level within the dock support leg to directly heat the fluid. In some embodiments, a portion of the heating element may extend above the fluid level while still heating the dock support leg wall and transferring heat into the cavity and surrounding water.

[0025] The heating element may be electrically coupled to a power supply (S) via one or more waterproof electrical connections (1,2). In one embodiment, the connector is an IP67-rated waterproof connector. In one embodiment, the connector comprises a threaded M14 connector having hot, neutral, and ground conductors. The heating assembly may be configured for use with 120V or 240V supply voltages.

[0026] In some embodiments, a ground fault circuit interrupter (GFCI) device is included in the heating assembly or kit to provide fault protection in wet or freezing environments.

[0027] In one preferred embodiment, an opening is formed in an upper region of the dock support leg, and the heating element is inserted through the opening into the cavity. The opening may be sized to receive the strain-relief grommet (F), which retains and seals around the heating element.

[0028] In another embodiment, the heating element is inserted through an open upper end of the dock support leg and retained by a grommet or retainer at the top.

[0029] During operation, the heating element heats fluid within the interior cavity and/or heats a wall of the dock support leg. This inhibits freezing within the dock support leg and reduces freezing and ice adhesion external to supporting legs, thereby reduces loads. In some conditions, the heating assembly creates a clearance zone adjacent the dock support leg. For example, the clearance zone may be at least about one-eighth inch and may be greater depending on ambient conditions, heater wattage, leg material, and water movement. The clearance zone is variable and non-limiting.

[0030] A plurality of heating elements may be installed in a plurality of dock support legs to protect a dock structure. In some embodiments, heating assemblies are physically daisy-chained using sealed connectors while being electrically connected in parallel such that each heating element receives supply voltage independently. In other embodiments, heating assemblies may be connected via a trunk line distribution arrangement or in other electrical configurations, including series connection.

[0031] In some embodiments, the heating element may be positioned along an exterior surface of the hollow dock support leg rather than within the interior cavity. For example, the heating element may comprise a heat-trace cable or other elongate heater secured to an outer wall of the dock support leg using one or more attachment structures, such as clamps, straps, bands, wraps, ties, adhesive, tape, a sleeve, shrink tubing, or combinations thereof. The heating element may extend longitudinally, may be arranged in a helical wrap, or may be otherwise distributed along the exterior surface, and may be disposed at or below a waterline during use. In some embodiments, an insulation layer or protective covering may be positioned over the heating element and/or the dock support leg to improve heat retention and/or protect the heating element from the environment. During operation, externally-applied heating may heat the wall of the dock support leg and/or heat fluid within the interior cavity through thermal conduction so as to inhibit freezing within the interior cavity and thereby mitigate freezing-related damage to the dock structure.

[0032] Referring to FIG. 3, in some embodiments the heating element (C) is disposed along an exterior surface of a hollow dock support leg (L) rather than within the interior cavity. In the illustrated embodiment, the heating element (C) comprises a heat-trace cable secured to the dock support leg (L) and arranged as a helical wrap around the dock support leg (L). The heating element (C) may be secured using one or more attachment structures, including, for example, clamps, straps, bands, ties, wraps, adhesive, tape, a sleeve, shrink tubing, or combinations thereof. During operation, the externally disposed heating element (C) heats a wall of the dock support leg (L) and transfers heat toward the interior cavity by thermal conduction, thereby inhibiting freezing within the interior cavity and reducing ice adhesion and loading external to the dock support leg (L). In some embodiments, at least a portion of the heating element (C) may be positioned at or below a waterline during use.

[0033] In some embodiments, an insulation layer or protective covering may be positioned over at least a portion of the heating element (C) and the dock support leg (L) to improve heat retention and/or to protect the heating element (C) from abrasion, ultraviolet exposure, and environmental wear. The heating element (C) may be electrically coupled to the power supply (S) via one or more waterproof electrical connections (1,2), which may include an IP67-rated connector, and a ground fault circuit interrupter (GFCI) device may be included to provide fault protection.

[0034] In some embodiments, the system may include a thermostat, temperature sensor, timer, controller, remote monitoring device, or networked control system. Such optional enhancements may control operation, improve efficiency, or provide status information.