1. Field of the Invention
The present invention relates generally to bypass valves for use in home or industrial water distribution systems that supply water to various fixtures at different temperatures through different pipes. More particularly, the present invention relates to such bypass valves that are thermostatically controlled so as to automatically bypass water that is not at the desired temperature for use at the fixture. Even more particular, the present invention relates to use of such a thermostatically controlled bypass valve in a water distribution system utilizing a single circulating pump at the water heater.
2. Background
Home and industrial water distribution systems distribute water to various fixtures, including sinks, bathtubs, showers, dishwashers and washing machines, that are located throughout the house or industrial building. The typical water distribution system brings water in from an external source, such as a city main water line or a private water well, to the internal water distribution piping system. The water from the external source is typically either at a cold or cool temperature. One segment of the piping system takes this incoming cold water and distributes it to the various cold water connections located at the fixture where it will be used (i.e., the cold water side of the faucet at the kitchen sink). Another segment of the piping system delivers the incoming cold water to a water heater which heats the water to the desired temperature and distributes it to the various hot water connections where it will be used (i.e., the hot water side of the kitchen faucet). At the fixture, cold and hot water either flows through separate hot and cold water control valves that are independently operated to control the temperature of the water into the fixture by controlling the flow rate of water from the valves or the water is mixed at a single valve that selectively controls the desired temperature flowing into the fixture.
A well known problem common to most home and industrial water distribution systems is that hot water is not always readily available at the hot water side of the fixture when it is desired. This problem is particularly acute in water use fixtures that are located a distance from the hot water heater or in systems with poorly insulated pipes. When the hot water side of these fixtures is left closed for some time (i.e., overnight), the hot water in the hot water segment of the piping system sits in the pipes and cools. As a result, the temperature of the water between the hot water heater and the fixture lowers until it becomes cold or at least tepid. When opened again, it is not at all uncommon for the hot water side of such a fixture to supply cold water through the hot water valve when it is first opened and for some time thereafter. At the sink, bathtub or shower fixture located away from the water heater, the person desiring to use the fixture will either have to use cold or tepid water instead of hot water or wait for the distribution system to supply hot water through the open hot water valve. Most users have learned that to obtain the desired hot water, the hot water valve must be opened and left open for some time so that the cool water in the hot water side of the piping system will flow out ahead of the hot water. For certain fixtures, such as dishwashers and washing machines, there typically is no method of xe2x80x9cdrainingxe2x80x9d away the cold or tepid water in the hot water pipes prior to utilizing the water in the fixture.
The inability to have hot water at the hot water side of the fixture when it is desired creates a number of problems. One problem is having to utilize cold or tepid water when hot water is desired. This is a particular problem for the dishwasher and washing machine fixtures in that hot water is often desired for improved operation of those fixtures. As is well known, certain dirty dishes and clothes are much easier to clean in hot water as opposed to cold or tepid water. Even in those fixtures where the person can let the cold or tepid water flow out of the fixture until it reaches the desired warm or hot temperature, there are certain problems associated with such a solution. One such problem is the waste of water that flows out of the fixture through the drain and, typically, to the sewage system. This good and clean water is wasted. This waste of water is compounded when the person is inattentitive and hot water begins flowing down the drain and to the sewage system. Yet another problem associated with the inability to have hot water at the hot water valve when needed is the waste of time for the person who must wait for the water to reach the desired temperature.
The use of bypass valves and/or water recirculation systems in home or industrial water distribution systems to overcome the problems described above have been known for some time. The objective of the bypass valve or recirculation system is to avoid suppling cold or tepid water at the hot water side of the piping system. U.S. Pat. No. 2,842,155 to Peters describes a thermostatically controlled water bypass valve, shown as FIG. 2 therein, that connects at or near the fixture located away from the water heater. In his patent, the inventor discusses the lack of hot water problem and describes a number of prior art attempts to solve the problem. The bypass valve in this patent comprises a cylindrical housing having threaded ends that connect to the hot and cold water piping at the fixture so as to interconnect these piping segments. Inside the housing at the hot water side is a temperature responsive element having a valve ball at one end that can sealably abut a valve seat. The temperature responsive element is a metallic bellows that extends when it is heated to close the valve ball against the valve seat and contracts when cooled to allow water to flow from the hot side to the cold side of the piping system when both the hot and cold water valves are closed. Inside the housing at the cold water side is a dual action check valve that prevents cold water from flowing to the hot water side of the piping system when the hot water valve or the cold water valve is open. An alternative embodiment of the Peters"" invention shows the use of a spiral temperature responsive element having a finger portion that moves left or right to close or open the valve between the hot and cold water piping segments. Although the invention described in the Peters"" patent relies on gravity or convection flow, similar systems utilizing pumps to cause a positive circulation are increasingly known. These pumps are typically placed in the hot water line in close proximity to the faucet where xe2x80x9cinstantxe2x80x9d hot water is desired.
U.S. Pat. No. 5,623,990 to Pirkle describes a temperature-controlled water delivery system for use with showers and eye-wash apparatuses that utilize a pair of temperature responsive valves, shown as FIGS. 2 and 5 therein. These valves utilize thermally responsive wax actuators that push valve elements against springs to open or close the valves to allow fluid of certain temperatures to pass. U.S. Pat. No. 5,209,401 to Fiedrich describes a diverting valve for hydronic heating systems, best shown in FIGS. 3 through 5, that is used in conjunction with a thermostatic control head having a sensor bulb to detect the temperature of the supply water. U.S. Pat. No. 5,119,988 also to Fiedrich describes a three-way modulating diverting valve, shown as FIG. 6. A non-electric, thermostatic, automatic controller provides the force for the modulation of the valve stem against the spring. U.S. Pat. No. 5,287,570 to Peterson et al. discloses the use of a bypass valve located below a sink to divert cold water from the hot water faucet to the sewer or a water reservoir. As discussed with regard to FIG. 5, the bypass valve is used in conjunction with a separate temperature sensor.
A recirculating system for domestic and industrial hot water heating utilizing a bypass valve is disclosed in U.S. Pat. No. 5,572,985 to Benham. This system utilizes a circulating pump in the return line to the water heater and a temperature responsive or thermostatically actuated bypass valve disposed between the circulating pump and the hot water heater to maintain a return flow temperature at a level below that at the outlet from the water heater. The bypass valve, shown in FIG. 2, utilizes a thermostatic actuator that extends or retracts its stem portion, having a valve member at its end, to seat or unseat the valve. When the fluid temperature reaches the desired level, the valve is unseated so that fluid that normally circulates through the return line of the system is bypassed through the circulating pump.
Despite the devices and systems set forth above, many people still have problems with obtaining hot water at the hot water side of fixtures located away from the hot water heater or other source of hot water. Boosted, thermally actuated valve systems having valves that are directly operated by a thermal actuator (such as a wax filled cartridge) tend not to have any toggle action. Instead, after a few on-off cycles, the valves tend to just throttle the flow until the water reaches an equilibrium temperature, at which time the valve stays slightly cracked open. While this meets the primary function of keeping the water at a remote faucet hot, it constantly bleeds a small amount of hot or almost hot water into the cold water piping, thereby keeping the faucet end of the cold water pipe substantially warm. If truly cold water is desired (i.e., for brushing teeth, drinking, or making cold beverages), then some water must be wasted from the cold water faucet to drain out the warm water. If the bypass valve is equipped with a spring loaded check valve to prevent siphoning of cold water into the hot water side when only the hot water faucet is open, then the very small flow allowed through the throttled-down valve may cause chattering of the spring loaded check valve. The chattering can be avoided by using a free floating or non-spring loaded check valve. Substantially warmed water in the cold water piping system is also undesirable as it requires re-adjustment of shower or tap valves to maintain a constant mix temperature while the xe2x80x9ctepidxe2x80x9d water is exhausted from the cold water pipe and replaced with cold water. This detracts from the users expectation of thermal bypass valve performance. It is also detrimental to have any noticeable crossover flow (siphoning) from hot to cold or cold to hot with any combination of faucet positions, water temperatures, or pump operation.
The thermostatically controlled bypass valve and water circulating system of the present invention solves the problems identified above. That is to say, the present invention provides a thermostatically controlled bypass valve placed at or near a fixture to automatically bypass cold or tepid water away from the hot water side of the fixture until the temperature of the water reaches the desired level. A single small circulating pump can be placed between the water heater and the first branch in the hot water supply line which supplies a fixture having a bypass valve to pressurize the hot water piping system and facilitate bypassing of the cold or tepid water.
In the primary embodiment of the present invention, the bypass valve is a generally tubular valve body having a first end (hot water side), a second end (cold water side) and a separating wall located therebetween. Preferably, the valve body is manufactured from a plastic material that is suitable for injection molding. The first end of the valve body has a first inlet port and a first discharge port and the second end has a second inlet port and a second discharge port. The separating wall has a passage that interconnects the first end and the second end of the valve body to allow water to flow from the first end to the second end. A thermally sensitive actuating element is disposed in the interior of the valve body at its first end. The actuating element has an actuating body and a rod member, the rod member being configured to operatively extend from the actuating body to seal against the passage located in the separating wall to prevent water flow therethrough. A bias spring is located in the valve body between the separating wall and the actuating body to urge the rod member toward the actuating body so as to open the passage. A check valve is located in the valve body at its second end to prevent flow of water from the cold water side to the hot water side.
In the preferred embodiment, the first and second inlet ports are axially disposed on the valve body, the first and second discharge ports are radially disposed on the valve body and the actuating element is a wax-filled cartridge actuator. The valve body has a positioning shoulder in its first end such that the actuating element abuts against this shoulder. An over-travel spring is located in the first end of the valve body between a mechanism for retaining the spring and the actuating element so as to urge the actuating body against the positioning shoulder. Preferably, the mechanism is a screen that is securably held in place by a retaining pin disposed in a retaining pin hole located in the first discharge port. The screen can be configured to be cleaned by the movement of water from the first inlet port to the first discharge port. The threads on the first and second inlet ports and on the first and second discharge ports can have flats or slots thereon. The bypass valve can be configured to be integral with a fixture, such as a faucet, shower, bathtub, washing machine or dishwasher, for use in a water distribution system having a hot water heater.
The present invention also describes a water circulating system for distributing water to at least one fixture which is configured for utilizing hot and cold water. The fixture has a hot water inlet and a cold water inlet. The hot water heater supplies hot water to the fixture through the hot water piping system that interconnects the hot water heater with the hot water inlet at the fixture. The system also has a source of cold water, such as the city water supply or a local well, for supplying cold water to the fixture through the cold water piping system that interconnects the source of cold water with the cold water inlet at the fixture. The source of cold water also supplies water to the hot water heater for distribution through the hot water piping system. As such, when the bypass valve is bypassing water the hot and cold water circulating systems form a loop. A thermostatically controlled bypass valve at the fixture interconnects the hot water piping system to the hot water inlet and the cold water piping system to the cold water inlet. The bypass valve is configured to bypass water from the hot water piping system to the cold water piping system until the water in the hot water piping system rises to a preset temperature value. The bypass valve can comprise the elements and be configured as described above. A single, small pump can be used in the hot water piping system to pump water through the hot water piping system to the hot water inlet on the fixture. In the preferred embodiment, the single pump is a low flow and low head pump and a check valve is used to pass water around the pump when the flow rate in the hot water piping system exceeds the flow rate capacity of the pump. An orifice can be located in the discharge of the pump to achieve the desired steep flow-head curve from available stock pumps. A mechanism for cyclically operating the pump can be used to reduce electrical demand and wear and tear on the pump and bypass valve. In addition, a flow switch can be connected to the pump for detecting the flow rate of the water in the hot water piping system and for shutting off the pump when the flow in the hot water piping system exceeds the flow rate capacity of the bypass valve. As above, the bypass valve can be manufactured to be integral with the fixture.
Accordingly, the primary objective of the present invention is to provide a thermostatically controlled bypass valve that is suitable for bypassing water from a hot water piping system to a cold water piping system at a fixture until the temperature of the water in the hot water piping system rises to a preset level for use at the fixture.
It is also an important objective of the present invention to provide a thermostatically controlled bypass valve that has a generally tubular valve body with two inlet ports and two discharge ports to connect to a fixture that utilizes hot and cold water and to sources of hot and cold water.
It is also an important objective of the present invention to provide a thermostatically controlled bypass valve that utilizes a thermally sensitive actuating element having a rod member configured to open and close a passage between the hot and cold sides of the bypass valve based on the temperature of the water adjacent to the fixture.
It is also an important objective of the present invention to provide a thermostatically controlled bypass valve that has a check valve in the cold water side of the bypass valve to prevent the flow of water from the cold water piping system to the hot water piping system.
It is also an important objective of the present invention to provide a thermostatically controlled bypass valve that utilizes a pump in the hot water piping system to circulate water from the hot water piping system to the cold water piping system through the bypass valve until the temperature of the water in the hot water piping system reaches a preset level.
It is also an important objective of the present invention to provide a thermostatically controlled bypass valve that is suitable for integrally incorporating into a fixture that utilizes hot and cold water.
USPTO Backgrounds
USPTO Backgrounds