1. Field of the Invention
This invention relates to a system for detecting water leaks and for closing a valve to shut off a water supply in the event of a leak, and more particularly to a system including a number of battery-powered leak detectors connected by a radio link to a receiver closing the valve.
2. Background Information
A typical structure, such as a house or commercial building, has a single input pipe through which water is supplied to a network of pipes carrying the water to various faucets and appliances. Alternately, a single structure may be divided into a number of dwellings or commercial areas, each of which has a single water input pipe supplying a network of pipes. In either case water leaks may develop in a number of locations, despite the fact that water comes into the structure or individual area through a single source, the input pipe. If a leak develops and is not detected, severe property damage generally results from the water which accumulates, since the water source continues to supply water which escapes through the leak. Furthermore, a personal safety problem arises when the water forms a slipping hazard on the floor, or if the water comes into contact with primary electrical wiring, such as wiring carrying 110 volts AC.
Water leaks are caused by failures within the appliances connected to the network of pipes or by failures within the network of pipes itself. Appliances prone to such failures include water heaters, washing machines, refrigerators with icemaking mechanisms, pipes or hoses associated with such appliances, and toilet flushing mechanisms. Failures within the network are often caused by ambient conditions which cause the water in certain pipes, such as pipes extending through or along poorly-insulated outside walls, to freeze, bursting the pipes. Serious flooding is also often caused by inadvertently leaving a faucet in a sink or tub running with the associated drain(s) blocked.
Thus, while there are a number of places where water leaks can be expected to occur, the locations where sensors must be placed to determine when such leaks may occur can generally be predetermined. For example, such sensors should be placed near or under appliances likely to develop leaking conditions, under pipes extending through or near exterior walls likely to promote freezing conditions, and at low points in bathrooms where sinks and tubs may be left with water running. While the locations of potential leaks can be determined, some of these locations, such as the places where pipes run through or near exterior walls, are not easily accessed. Such locations may, for example, by in crawl spaces under floors. Any sensing unit placed in such a location cannot easily be serviced with line current, such as 110 volts AC. Any visual indication given directly by a sensing unit in such a location will probably not be noticed. While an audio indication, such as a buzzer, given directly by a sensing unit in such a location may be heard, its meaning, including the location of the unit, may be difficult to determine, and a leak may occur in a building when no one is inside. Furthermore, the input pipe, through which water is brought into the structure, is typically in a location which is not easily accessed. While a solenoid valve in this location can effectively be used to shut off the flow of water, visual and audible indications in this location may not be noticed or understood.
Thus, a system for detecting leaks and for providing an alarm when they occur should include sensors capable of placement in remote locations not having line current. Visible indications, such as alarm lights, should be placed both at the sensing unit and at the solenoid valve. Audible indications should also be placed both at the sensing unit and at the solenoid valve, and should be differentiated, one from another, so that the source of a leak can be determined even if the leaks and sensing units are not accessible.
Since the conditions which cause water leaks, such as extremely low outside temperatures, often also cause the interruption of electrical power, it is particularly desirable that such a system should operate properly without line power, using batteries for energy storage.
The potential danger of having electrical wiring attached to the power lines in locations of standing water is well known. While this danger can be alleviated by proper design measures, such as watertight enclosures and circuits providing electrical isolation, a particularly simple and effective way to avoid this danger is the use of battery power without electrical line power to operate all sensor units. What is therefore needed is a system having a number of sensors operating on individual batteries.
The most serious water leaks, in terms of property damage, are typically leaks which occur in unattended conditions. It is therefore highly desirable that a system capable of recognizing water leaks and providing alarms should also be capable of taking action to shut off the water at an input pipe so that further damage is prevented.