Automatic Control System For Limiting Ice Formation In Gutters And Downspouts

Abstract

A gutter waste sensor comprising a grounded electrode and a water sensing electrical probe mounted on an insulated block which is vertically adjustable to various levels on a hollow stand extending upward from the bottom of the gutter. The water sensing probe is located and spaced protectively between members of the vertical stand. The grounded electrode terminates on the stand at a lower level than the probe. The probe and grounded electrode are part of a solid state electronic circuit for detecting the presence of water at the predetermined level in the gutter and energizing an electrical heating cable system laid therein to limit the accumulation of ice and prevent the overflow of water therefrom during a thaw.

Description

BACKGROUND OF THE INVENTION

Often during the winter, while the atmospheric temperature is below the freezing point of water, some of the snow on the roof melts in the sunlight and the resulting water runs off the roof and freezes in the gutter and downspout. After a number of such thaws, enough ice accumulates in the drains to prevent further drainage, the final result being a gutter completely filled with ice. Water from further melting of roof snow can then only overflow the gutter, forming icicles thereon and ice accumulation on surfaces below the gutter. Thus stairs and sidewalks become extremely slippery and dangerous for walking. Trees and shrubs may be severely damaged. Even if walks are made temporarily safe by the application of salt and sand, this still requires repeated attention and pedestrians may yet be injured by falling icicles. In addition, ice may accumulate on the eaves to such an extent that water will seep under the roofing, damaging the roof, eaves and soffit, and sometimes the house interior.

It has been the practice in the past to lay electrical heating cable along the bottom of the gutter and through the length of the rainpipe and wait until a snowfall or thaw before manually throwing a switch to connect the cables to an electrical power supply for melting the snow and ice in the drains and keeping them clear for drainage. Unfortunately, this requires watching and waiting. Even if weather conditions are carefully observed, the time to turn the heating cables on or off is conjectural, unless the operator is able to visually inspect the gutter and roof for the presence of ice or snow jam that will lead to stoppage of drainage if not melted. Such guessing can be uneconomical in the use of electricity or disastrous in the overflow of the gutter with water, since either too much or too little power can make all the difference in the results attained with the manually controlled system for limiting ice formation in gutters and downspouts. The prior art discloses an electrolytic system for sensing the presence of water in the gutter and downspout and energizing heating cable placed therein. That system had the disadvantage of (1) a short lift due to electrolytic decomposition of its switchplates, and (2) possible hazardous operation if instructions were not strictly followed.

There is an established need for a safe, simple and reliable device for automatically limiting ice accumulation in gutters and downspouts in which safety is improved by using a low-voltage sensing circuit. In the present invention, practicality is enhanced by having a small, compact water sensor closely associated with the heating cable in the gutter to reduce obstruction of the drain, and greater reliability is derived from a sensor which is kept free of ice and is permeable by water at all times.

SUMMARY OF THE INVENTION

The gist of this invention lies in an electronic water sensor comprising a water sensing probe which is mounted between two vertical legs of an inverted current-conducting T-shaped stand with the cross leg of the T serving as a base for resting on the bottom of the gutter. The water sensing probe is insulated from and spaced protectively between the vertical legs of the stand. One of the vertical legs and the cross leg of the stand, at a lower level than the probe, is the ground terminal. A 10-volt solid state electronic control circuit in combination with the water sensor probe electrically connects a heating cable installed in the roof drains to a 120-volt power supply for melting the accumulated ice and snow.

The vertical legs of the inverted T-shaped sensor stand serve also as a framework for supporting an enfolding loop of the gutter heating cable which makes a drain tunnel through any ice overlying the cable and provides a drain path for water on the top of accumulated ice and snow to reach the bottom of the gutter. Air also enters the tunnel melted around the enfolding cable loop, easing the flow of water by eliminating siphon restrictions. A slipknot in the heating cable at the enfoldment may be used to encircle the bottom of the inverted T-stand. This restores horizontal continuity of the drainage path and assures quick melting and complete drainage of the sensor area.

Additional plain loops for drainage may be formed by simply gathering at intervals several inches of heating cable into a tied, doubled section and resting each loop thus formed on the gutter bottom. The top of each additional plain loop is secured to a gutter hanger strap by insulated wire or tape. The optimum distance between successive vertical drainage loops in the gutter is indeterminate because of the differences in installation sites. Initially, a loop every 8 to 10 feet of gutter is suggested, but this may be varied considerably according to experience and expected conditions.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a fragmentary perspective view of a corner of a house, showing a gutter, downspout and the housing for electrical components secured to the gutter;

FIG. 2 is a fragmentary perspective view of a gutter, showing a sensor stand in the gutter near the downspout;

FIG. 3 is a cross-sectional view of the gutter along line 3--3 of FIG. 2 showing an electric heating cable loop enveloping the stand of the gutter water sensor;

FIG. 4 is a fragmentary cross-sectional view of the gutter along line 4--4 of FIG. 2 showing an electrical heating cable loop enveloping the stand of a water sensing probe;

FIG. 5 is a side elevational view of a laminated blocktype water probe on a sensor stand;

FIG. 6 is a side view taken along the lines 6--6 of FIG. 5;

FIG. 7 is a bottom plan view of the sensor stand along lines 7--7 of FIGS. 5 and 11;

FIG. 8 is a fragmentary side elevational view of the sensor probe of FIG. 5 mounted in the block with the stand removed;

FIG. 9 is an end elevational view taken along the lines 9--9 of FIG. 8;

FIG. 10 is a bottom view taken along the lines 10--10 of FIG. 8 but including the lower ends of the legs of the inverted T-shown shown in cross section with the laminated block clamped thereto;

FIG. 11 is a side elevational view of a water sensor in which the electronic components are encapsulated in its own inverted U-housing;

FIG. 12 is an end view taken along the lines 12--12 of FIG. 13;

FIG. 13 is a side elevational view of the sensor with the encapsulated components shown in FIG. 11 with the inverted T-stand removed;

FIG. 14 is a side elevational view taken along the lines 14--14 of FIG. 13;

FIG. 15 is a circuit diagram of the 10-volt solid state electronic system for connecting heating cables to a 120-volt AC power supply;

FIG. 16 is a perspective view of a modified form of an inverted T-stand; and

FIG. 17 is a cross sectional view taken along the lines 17--17 of FIG. 16 but also showing one means of securing the heating cable to the horizontal legs of the stand.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring to the drawings, my invention is designed to limit ice formation and blockage in gutter G and downspout D by heating cable C laid therein, as shown in FIG. 1, and by the electrical power box B, housing the control circuit, when the presence of water is detected by a gutter water sensor 8 installed therein, as shown in FIGS. 2, 3 and 4.

In FIGS. 5-10 is illustrated an embodiment of the gutter water level sensor 8 comprising an upright inverted T-stand 9, preferably made of copper or other bare, weather-durable metal, having a horizontal base member 10 which mounts a pair of spaced vertical legs 13 and 13' connected together at their top by loop 12. The leg 13 is bent horizontally adjacent its lower end and then back upon itself. The leg 13' is also bent horizontally adjacent its lower end, all as clearly shown in FIG. 5, to form base 10.

A ground lead 14 connects to the bare metal of the first plate member 11, as shown in FIGS. 5 and 6, which is clamped by screws 15 to the outer face of the leg 13. The other end of the lead 14 is connected to the tap 51. A laminated insulating block 16 mounts between the side members 13 and 13' and is positioned adjacent the upper end thereof. The laminated insulating block 16 is held against the inner face of and supported by the side member 13 by the screws 15 in appropriate threaded apertures 15' in said block 16, as shown in FIG. 8, in a clamping action on opposite sides of member 13. A water sensing probe 18, which is insulated except for a portion of its tip 18', is protectively and adjustably held substantially medially between members 13 and 13' by the laminated block 16 in which the probe is threaded, as shown in FIGS. 5, 8, 9 and 10, at an adjustable distance up from the base 10 of the stand 9. A lead 19 connects with the sensing probe 18 at one end and to the other to the resistor 47. An aperture 17 is provided in the base member 10 between the side members 13 and 13', as shown in FIG. 7, so that water can encroach easily upon the water sensing probe tip 18' and recede completely therefrom leaving no puddle, capillary, droplet or wet surface for residual conduction between the electrode tip 18' and ground. The base 10 normally is positioned flat against the bottom of the drain G. The water sensing probe, which may be plastic insulated, number 20, solid hookup wire, is a straight member pointed downward with about a half-inch of insulation removed from the tip 18', exposing the conductor to contact with any water in the gutter.

Referring to FIG. 15, the solid state electronic control circuit 20 in housing B comprises a silicon controlled rectifier circuit 41 having a thyristor 44, preferably of the Type 2N5060, with a sensitive gate 45, anode 46 and cathode 48. The gate 45 has a switching action responsive to a small signal current passed through the water sensor 8. The gate 45 is electrically connected to the sensor ground lead 14 and to the first terminal 51 of preferably a 0.01 microfarad capacitor 50. The anode 46 is electrically connected through preferably a 30,000 to 45,000-ohm resistor 47 to lead 19, probe 18 and tip 18' of water sensor 8. The anode 46 is also electrically connected to the first terminal 56 of heater 49 in the thermal relay 57. The cathode 48 is electrically connected to the second terminal of capacitor 50 by lead 52 and to the first terminal 58 of secondary coil 55 of transformer 59.

In FIG. 15, the thermal time delay relay 57 comprises a heating element 49 and a normally-open thermostatic switch 63. The heating element 49 has a second terminal 54 connected to the second terminal 60 of secondary coil 55 of transformer 59, for energizing the heating element 49 when the silicon controlled rectifier circuit 41 is fired by the presence of water between the probe tip 18' and the sensor stand 9.

In FIG. 15, a normally-open bimetallic single-pole, single-throw switch 63 in the thermal relay, having first and second electrical terminals 62 and 64, is actuated by the heating element 49 for closing the contacts of the switch after a rated delay period and connecting terminals 62 and 64 in the 120-volt AC power supply circuit between one side of the primary coil 61 and one side of receptacle 65, respectively, for energizing the receptacle 65 and heater cable C when its plug is electrically connected to receptacle 65.

The transformer 59 has an input of 120 volts at the primary coil 61 connected to power supply wires 32 and 33 and has a 10-volt, 5-watt output from secondary coil 55 connected to the sensor circuit at terminals 58 and 60. The transformer has a built-in automatic resetting thermal protector, not shown in FIG. 15.

In the operation of this system for limiting the formation of ice in the gutter G and the downspout D, a critical level of water in the gutter G of FIG. 1 actuates the water sensor 8, as shown in the circuit diagram of FIG. 15, and produces an electrical signal which is connected to and fires the silicon controlled rectifier circuit 41 and energizes the thermal relay 57, which in turn, after a rated delay, connects the 120-volt AC power supply to the heating cable C which is laid in the gutter G and the downspout D. The slow-acting delay relay prevents repeated short term operations of the switch 63 by fluctuant water in the gutter, thereby greatly reducing contact wear.

Reversely, water receding below the critical level in the gutter opens the circuit in sensor 8 and makes the silicon controlled rectifier circuit 41 non-conductive. The resultant cooling of heater 49 allows the switch 63 to return after a delay to its normally open position, turning off the heating cable plugged into receptacle 65.

In FIGS. 2, 3 and 4, a gutter strap 30 supports the vertical leg of the sensor stand 9, while the base 10 rests on the bottom of the gutter. An insulated wire loop 31 ties the connector 12 of the stand 9 to the strap 30. The vertical leg of the sensor stand 9 is long and narrow and sets upright on the bottom of gutter G. The water sensor 8 is preferably located near the downspout D, because this is the lowest level of the gutter G and accumulating water therein can first be detected there.

FIG. 3 also shows the heating cable C tied to form a loop 34 over the side members 13 and 13' and secured at the connector 12 to the gutter strap 30 by the tie 31. The bottom of the loop is tied by making a slipknot 35 in the heating cable C, adjacent to the base 10 of the stand 9, to insure adequate drainage to the bottom of the gutter. The heat of the cable C around the legs will tend to dry up any water or droplets in the area between the side members 13-13' during the time delay period mentioned hereinabove.

Additional simple loops, tied closed with tape or insulated wire, may be formed without sensor or stand every 8 to 10 feet along the gutter length and secured to other gutter straps, primarily to allow water to flow along the heating cable C lying on the gutter bottom by means of drainage holes melted in the ice depth and regardless of the depth of ice overlying the cable.

In FIGS. 11 to 13, another embodiment of the gutter water sensor 8' comprises the silicon controlled circuit 41 (see FIG. 15) comprising the thyristor 44, resistor 47 and capacitor 50 embedded in the insulator capsule 24, which is housed in a U-shaped current conducting sheet metal member 21 having legs 22 and 23 fitting between the side members 13 and 13' of the upright member 9 (see FIG. 11). A clamp member 25, soldered to the outer side of leg 22, extends beyond the width of leg 22 with appropriate threaded holes therein. The clamp is wrapped around side member 13' of the member 9 and locks the sensor 8' at an adjustable height on the member 9 by tightening screws 26. The member 13' is electrically connected to the clamp by sliding contact pressure. In the embedded circuit, the ground lead 14, FIG. 15, is electrically connected to the leg 22 and hence through the clamp to member 13', while the probe 18' of FIGS. 11 and 12 emerges directly as a bare conductor from the embedding material of capsule 24, which holds all elements of circuit 41, FIG. 15, fixed and insulated. Of course, as in the main embodiment, the probe 18' is electrically connected to the resistor 47 and the anode 46.

When circuit 41 of FIG. 15 is thus spatially separated from other elements of the control circuit 20 in box B and is distantly encapsulated in sensor 8' of FIGS. 11-14, then the conductors 70 and 71 of FIG. 15 become leads for joining sensor 8' and circuit 41 to control box B at the first terminal 58 of the secondary coil 55 of transformer 59 and at the first terminal 56 of heater element 49 of thermal delay relay 57.

In the modified form of the invention in FIGS. 16 and 17, a relatively heavy rectangular-shaped plate 80 is anchored to the lower face of horizontal legs 10 by bonding as at 82, medially of the side edges 81 of the plate. This plate is preferably constructed of lead or zinc approximately 11/2 inches wide and 31/8 inches long. The plate is provided with an aperture identical to the aperture 17 in the horizontal leg 10 whereby water in the gutter may enter between the members 13-13'. Water may also readily drain to the gutter when the water in the gutter is drained off.

The purpose of adding the plate 80 to the inverted T-stand 9 is to allow the stand 9 to seat freely in the gutter without using the ties 31, shown in FIGS. 2, 3 and 4.

As shown in FIGS. 16 and 17, the plate 80 is provided with a series of spaced apertures 83 on each side of the horizontal leg 10 for the purpose of using a lace 84 to tie the heater cable to the upper surface of the plate 80.

Thus it should be apparent from the foregoing that the component cost is small, the water sensor operates on safe low voltage, and multiple sensors may be used in simple parallel connection without requiring increased power for sensing.

It is to be understood that various details shown and disclosed may be altered or omitted without departing from the spirit of this invention as defined by the following claims.

Claims

I claim:

1. In an automatic control system for limiting ice formation in gutters having electrical heating cables laid therein, the combination comprising:

a. a gutter,

b. a water level sensor including an electric probe for sensing the level of water in the gutter,

c. an electronic switch connected to the sensor and to the heating cable, and

d. a power supply connected to the switch.

2. In the control system as set forth in claim 1 wherein the water level sensor comprises:

a. an upright stand having a top and a base for mounting on the bottom of the gutter, and

b. wherein the electric probe is mounted on and insulated from the stand between the top and the base.

3. In the control system as set forth in claim 2 wherein the stand comprises:

a. a horizontal leg, and

b. a plurality of spaced vertical members mounted to the leg for protectively mounting the probe therebetween.

4. In the control system as set forth in claim 3 wherein the upright stand comprises:

a. a heating cable looped over the vertical legs and secured to the top of the stand, and

b. a cable loop wound around the juncture of the base and the upright stand.

5. In the control system as set forth in claim 1 wherein the switch comprises:

a. a transformer having a primary circuit connected to the power supply,

b. a thyristor control circuit connected to one terminal of the secondary circuit of the transformer, and

c. an electrical relay having one terminal connected to the thyristor and the other terminal connected to the other terminal of the secondary circuit of the transformer.

6. A water level sensor comprising a conducting metal stand having a horizontal base member which mounts a hollow vertical leg having a top and side members, and uninsulated ground lead connected to the bare metal of the stand, a laminated insulating block mounted between the side members intermediate between the top and the base of the stand, a water sensing probe protectively mounted on and extending downward from the laminated block at a distance up from the base of the stand, a water sensing probe lead connecting with the sensing probe comprising insulated hookup wire, a heater cable, a vertical loop of the heating cable on the vertical leg of the stand, and a loop of heating cable tied around the vertical leg adjacent to the horizontal base member, all connected in an electrical circuit whereby in the presence of water between the side members and the probe, the electrical circuit will be operable.

7. The device of claim 6 wherein the electrical circuit comprises a small signal thyristor in a rectifier circuit, a thermal delay relay and a transformer.