Abstract:
A hot water recirculation system includes a source of hot water, a fixture, a fluid circuit, a fluid pump, and an electrical circuit sensor. The fixture is remote from the source of hot water and is configured to dispense hot water. The fluid circuit extends from the source to the fixture for delivering hot water to the fixture. The fluid circuit returns to the source for recirculating hot water in the fluid circuit back to the source for reheating. The fluid pump is configured for recirculating hot water through the fluid circuit. The electrical circuit sensor is configured to detect operation of an electrical circuit proximate the fixture and associated with a user operating the fixture. The electrical circuit sensor is further configured to initiate operation of the fluid pump responsive to detected operation of the electrical circuit to initiate hot water recirculation. A method is also provided.

Description:
TECHNICAL FIELD  
       [0001]     The present invention pertains to hot water supply and heating systems that conserve water and energy. More particularly, the present invention relates to hot water recirculation systems.  
       BACKGROUND OF THE INVENTION  
       [0002]     Numerous hot water recirculation systems are known to exist for delivering hot water to a fixture within a building. The water is recirculated in order to make hot water instantly available at the fixture when the fixture is turned on. Also, hot water is recirculated in order to conserve water usage because unrecirculated water is typically delivered down a drain while an operator of a fixture waits for hot water to reach the fixture.  
         [0003]     U.S. Pat. No. 4,201,518 discloses one system for recirculating hot water. Manually operated push button switches are wired into positions adjacent to hot water fixtures, or taps, within a house. The push buttons operate a time delay circuit that turns on a recirculation pump for a set time interval to circulate hot water through the system. However, electrical wiring must be run from each hot water tap in the system to a central control circuit for a recirculation pump. Since hot water taps are distributed throughout a building or home, this can entail a significant amount of wiring. Furthermore, dedicated push button switches need to be wired into locations adjacent each hot water tap. This entails further expense and complexity in installing the system. Furthermore, the use of dedicated push button switches requires that a user manually activate the push button switch in order to initiate hot water recirculation for the respective hot water tap, which requires that a user remember to turn on the switch.  
         [0004]     U.S. Pat. No. 5,205,318 discloses another hot water recirculation system. This system uses a cold water line, or pipe, in combination with a hot water line to recirculate hot water. The system is placed near a hot water fixture. The system pulls water from the hot water line and places it into the cold water line until water in the hot water line reaches a set temperature. However, this makes water in the cold water line warm or hot. Additionally, temperature in the cold water line now varies greatly, and this may require that a user needs to aggressively and continuously adjust the fixture in order to realize a desired water temperature at the fixture, as temperature in the cold water line varies. Furthermore, cold water will be wasted at the fixture in order to obtain cold water at the fixture, and hot water that enters the cold water line can end up at other cold water fixtures. Even furthermore, power needs to be installed adjacent to the system, or unit, which is near the fixture. The system is also prone to failure due to accumulation of hard water deposits that can cause the system to stick into an open position, thereby wasting hot water and sending hot water to all the cold water outlets throughout the system.  
       SUMMARY OF THE INVENTION  
       [0005]     A hot water recirculation system is provided that reduces complexity and cost of installation, while also eliminating the need that a user remember to physically trigger initiation of hot water recirculation before using a hot water fixture. The system uses existing electrical wiring to detect a need to initiate hot water recirculation. Secondly, the system uses existing electrical switches that accompany usage of the fixture, such as an overhead light or a power switch for a device that has the fixture.  
         [0006]     According to one aspect, a hot water recirculation system includes a source of hot water, a fixture, a fluid circuit, a fluid pump, and an electrical circuit sensor. The fixture is remote from the source of hot water and is configured to dispense hot water. The fluid circuit extends from the source to the fixture for delivering hot water to the fixture. The fluid circuit returns to the source for recirculating hot water in the fluid circuit back to the source for reheating. The fluid pump is configured for recirculating hot water through the fluid circuit. The electrical circuit sensor is configured to detect operation of an electrical circuit proximate the fixture and associated with a user operating the fixture. The electrical circuit sensor is further configured to initiate operation of the fluid pump responsive to detected operation of the electrical circuit to initiate hot water recirculation.  
         [0007]     According to another aspect, a system is provided for initiating hot water recirculation. The system includes a hot water tank, a hot water fixture, a hot water fluid conduit, a hot water pump, and an electrical power relay. The hot water tank has a hot water heater. The hot water fixture is disposed from the hot water tank and is configured to dispense hot water to a user. The hot water fluid conduit includes a hot water pipe loop extending from the hot water tank to the fixture and back to the hot water tank to enable passage of hot water in a single direction through the fluid conduit to the fixture and back to the hot water tank for reheating. The hot water pump is disposed in the fluid conduit downstream of the fixture and proximate the hot water tank. The hot water pump is configured to recirculate hot water through the fluid conduit and back into the hot water tank for reheating. The electrical power relay is configured to detect current flow through an electrical power circuit for a fixture that is proximate and associated with the hot water fixture. The electrical power relay is further configured to initiate power delivery to the hot water pump responsive to the relay detecting operation of current flow through the electrical circuit to initiate hot water recirculation.  
         [0008]     According to yet another aspect, a method is provided for recirculating hot water through a continuous loop fluid circuit, which includes providing a source of hot water disposed within a continuous loop fluid conduit with at least one fixture disposed along the fluid conduit; detecting operation of an electrical circuit proximate the fixture and associated with a user operating the fixture, in response to detecting operation of the electrical circuit, recirculating hot water through the fluid conduit. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]     Preferred embodiments of the invention are described below with reference to the following accompanying drawings.  
         [0010]      FIG. 1  is a simplified diagrammatic representation with parts broken away and illustrating a first embodiment of the present invention installed in a residential home.  
         [0011]      FIG. 2  is a simplified perspective view of a circuit breaker box into which relay current sensors are provided to detect operation of power circuits associated with a respective hot water fixture. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0012]     This disclosure of the invention is submitted in furtherance of the constitutional purposes of the U.S. Patent Laws “to promote the progress of science and useful arts” (Article 1, Section 8).  
         [0013]     Reference will now be made to a preferred embodiment of Applicant&#39;s invention in the form of a hot water recirculation system. While the invention is described by way of a preferred embodiment, it is understood that the description is not intended to limit the invention to such embodiments, but is intended to cover alternatives, equivalents, and modifications which may be broader than the embodiments, but which are included within the scope of the appended claims.  
         [0014]     In an effort to prevent obscuring the invention at hand, only details germane to implementing the invention will be described in great detail, with presently understood peripheral details being incorporated by reference, as needed, as being presently understood in the art.  
         [0015]      FIG. 1  illustrates a hot water recirculation system identified by reference numeral  10 . System  10  is implemented within a building, such as a residential home, to deliver recirculated hot water to selected hot water fixtures that are distributed about the home. However, it is understood that system  10  can be implemented within any building or any environment having a hot water delivery system.  
         [0016]     For example, hot water is delivered to fixtures within a kitchen  12 , a bathroom  14  and a laundry room  16  via a hot water supply line, or pipe,  20  that forms a continuous loop through the home. Hot water supply line  20  is configured in a continuous loop in order to enable recirculation of hot water therein. Cold water is delivered to fixtures within kitchen  12 , bathroom  14 , and laundry room  16  via a cold water supply line  18 .  
         [0017]     As shown in  FIG. 1 , a supply of hot water is generated within a hot water tank  38  via a gas-fired heater or electric heating elements (not shown) of tank  38 . Hot water supply line  20  receives hot water from tank  38  via a hot water outlet fitting  41 , and recirculates water from within line  20  back into tank  38  via a water inlet fitting  39  for reheating. Hot water supply line  20  provides a return line  22  for recycling water from line  20  back into tank  38  by passing the water into a main water supply line  24 , downstream of a one-way check valve  25 . Cold water supply line  18  branches off main water supply line  24  upstream of check valve  25 . Check valve  25  provides one-way flow of water toward tank  38  and prevents water in line  20  from being delivered upstream into line  24  which would otherwise introduce heated water into cold water supply line  18 .  
         [0018]     A recirculation control system  26  is provided by system  10  for controlling movement of water within hot water supply line  20 . More particularly, system  26  includes a shutoff valve  28  (optional), a water recirculation pump  30 , a check valve  32 , a shutoff valve  34  (optional), and a thermal switch  36  (optional). Shutoff valves  28  and  34  can be used to close line  20  on either side of pump  30 . In this manner, line  20  can be shut off on both sides of pump  30 , which enables removal and replacement of pump  30  during regular maintenance or repair. Additionally, either one of valves  28  and  34  can be used to close down line  20  when it is desired to disable recirculation features of the present invention. Check valve  32  allows one-way flow of water toward tank  38 . Optionally, the locations of pump  30  and check valve  32  can be interchanged. Similarly, check valve  25  allows one-way flow of water toward tank  38 .  
         [0019]     According to one construction, water recirculation pump  30  comprises a gear rotor pump. Alternatively, pump  30  comprises a centrifugal pump, an impeller pump, a diaphragm pump, or any other pump suitable for pumping water in a single direction through a line or pipe circuit, or loop.  
         [0020]     As shown in  FIG. 1 , shutoff valves  28  and  34  are optional and one or both can be removed in an alternative implementation. Furthermore, thermal switch  36  is also optional. However, thermal switch  36  can be used to detect a desired setpoint temperature at the downstream end of the hot water loop provided by line  20 . If the temperature at the downstream end of line  20  does not drop below a desired setpoint (as detected by thermal switch  36 ), the recirculation system can be prevented from turning back on and initiating recirculation of hot water through line  20 .  
         [0021]     As shown by the implementation of hot recirculation system  10  within a home or building, various hot water fixtures are distributed about rooms  12 ,  14 , and  16  within a house such that all hot water fixtures are presented in series along a loop provided by hot water line  20  as line  20  passes circuitously through the house and back to hot water tank  38 . As shown in  FIG. 1 , system  10  is activated when power is used by devices that are associated with the hot water fixture present in a respective room. For example, when an overhead light is turned on by light switch  44  within kitchen  12 , a relay  47  detects current flow through an electrical line  46  associated with light switch  44 . Preferably, relay  47  is actually mounted about electrical line  46  where line  46  passes within a fuse box  88  (see  FIG. 2 ). Alternatively, relay  47  can be mounted anywhere between switch  44  and fuse box  88  (of  FIG. 2 ). In this manner, when lights are turned on in the kitchen, hot water circulation is implemented within line  20 . This action will ensure that hot water will be more quickly available to a user when the user subsequently opens hot water faucet  52  to deliver hot water via spout  53  into the kitchen sink  40 . Additionally, the initiation of hot water recirculation via line  20 , resulting from turning on of switch  44 , also presents hot water to a dishwasher  42  present within the kitchen  12 . However, an additional trigger is rendered for initiating hot water recirculation for dishwasher  42 , in the event that the kitchen light is not turned on. More particularly, a second relay  50  is provided about an electrical line  51  that supplies power to operate dishwasher  42 . When an operating switch  48  is used to turn on dishwasher  42 , relay  50  detects electrical current flow through electrical line  51  and thereby initiates operation of pump  30  and imparts hot water recirculation through line  20 . Again, relay  50  is preferably mounted within fuse box  88  of  FIG. 2 . Alternatively, relay  50  can be mounted anywhere along electrical line  51  which is wired to provide power to dishwasher  42 . Hence, relay  50  detects power consumption by dishwasher  42  when dishwasher  42  is initially turned on.  
         [0022]     Also shown in  FIG. 1 , cold water supply line  18  provides cold water in series with each of the appliances present within kitchen  12 , bathroom  14 , and laundry room  16 . For example, the cold water faucet  54  is used to turn on and off a cold water supply to spigot  53  in kitchen sink  40 . Likewise, a cold water faucet  68  is used to turn on and off a supply of cold water from line  18  through a spigot  67  of a bathroom vanity sink  56 . Furthermore, a hot/cold water faucet  70  is provided within a shower  60  of bathroom  14  to supply cold water (or a mixture of cold and hot water) via a showerhead outlet  72 . Line  18  also supplies cold water to toilet  58  within bathroom  14 . Even furthermore, line  18  provides a supply of cold water to clothes washer  74  within laundry room  16 .  
         [0023]     As shown within bathroom  14  of  FIG. 1 , a bathroom light switch  65  is turned on by a user of bathroom  14 , which triggers hot water recirculation through line  20  to provide hot water to bathroom vanity sink  56  and shower  60 . More particularly, electrical wire  63  is encircled by a relay  64  that detects current flow when switch  65  is turned on in order to turn on an overhead bathroom light fixture (not shown). Relay  64  monitors current flow through electrical wire  63 , which then closes a circuit that turns on operation of pump  30  in order to initiate hot water recirculation through the closed loop provided by hot water line  20 .  
         [0024]     In the case of bathroom vanity sink  56 , a hot water faucet  66  is turned on in order to deliver the recirculated hot water via spigot  67  into sink  56 . Likewise, by rotatably positioning hot/cold water faucet  70  in shower  60  to a position that requires hot water, recirculated hot water is delivered through showerhead outlet  72  and into shower  60 .  
         [0025]     As shown in laundry room  16  of  FIG. 1 , clothes washing machine  74  includes power circuitry that is used to turn on washing machine  74  when a user desires to wash a load of clothes therein. More particularly, a timing/operation switch  76  enables initiation of a wash cycle by washing machine  74  when a user turns on switch  76 . Mode switches  78  enable a user to vary the intensity or duration of the operating mode selected by a user for washing machine  74 . Washing machine  74  receives power via an electrical wire  82  such that current is detected by a relay  80  when the washing machine cycle is turned on by selectively activating switch  76 . Accordingly, a user typically initiates operation of washing machine  74  by activating switch  76  to a desired operating mode, at which time electrical current passes through electrical wire  82 . Relay  80  (preferably placed in fuse box  88  (of  FIG. 2 )) immediately detects operation of washing machine  74  and initiates hot water recirculation through line  20 . Hence, hot water recirculation commences as soon as a user turns on washing machine  74 .  
         [0026]     As identified by the various hot water fixtures in  FIG. 1 , operation of switches  44  and  65  and switches  48  and  76  each individually trigger hot water recirculation through line  20  without requiring that a user activate a separate, dedicated switch within the respective room. In each of these cases, the user is already required to activate the respective switch in association with utilizing the related, or associated, hot water fixture. For example, a user will normally be required to turn on an overhead light within a kitchen before using sink  40  and activating hot water faucet  52  to deliver hot water-into sink  40 . Likewise, a user will be required to activate switch  65  in order to turn on a bathroom light so that they can see before activating hot water faucet  66  within sink  56 . Similarly, a user will activate switch  65  in order to use shower  60  and thereby activate hot water recirculation through line  20  before actual actuation of hot/cold water faucet  70  of shower  60 . Finally, a user will typically be required to turn on washing machine  74  before initiating operation of a washing machine cycle.  
         [0027]     In this manner, a user does not have to remember to activate a separate, dedicated switch in order to initiate hot water recirculation through line  20  within a house or building. Likewise, existing wiring can be utilized to trigger detection of a need to recirculate hot water within line  20  by merely utilizing relays  47 ,  50 ,  64  and  80 . These relays each detect current flow through existing electrical wires that provide independent power functions within the building that are associated with utilization of the rooms in which the desired hot water fixtures are to be used.  
         [0028]     For the case of clothes washing machine  74 , an optional configuration entails providing relay  80  configured about an electrical wire that supplies power to an overhead light for laundry room  16 . Where laundry room  16  is used solely for washing and drying clothes, utilization of relay  80  on the respective light switch will trigger hot water recirculation through line  20  immediately when a user turns on the respective light switch. Accordingly, hot water recirculation will be initiated earlier in time, even before a user has had a chance to turn on switch  76 . Likewise, dishwasher  42  can utilize the benefits of hot water recirculation that are triggered solely by activation of switch  44 , and relay  50  optionally can be eliminated for cases where it is believed that a user will turn on light switch  44  prior to each time they initiate a washing cycle using dishwasher  42 .  
         [0029]     For the case of relays  47 ,  50 ,  64 , and  80 , each relay ties into power that is going to a respective light switch or appliance in order to activate hot water recirculation in line  20  via pump  30 . It is understood that the respective relays can be configured to be activated by either  110 ,  220 , or  440  volts, depending on the voltage of the respective circuit being monitored.  
         [0030]     For the optional case where a thermal switch  36  is incorporated into the design of system  10 , thermal switch  36  can be used to shut down operation of pump  30  once thermal switch  36  detects a sufficiently high temperature within the downstream end of the closed loop provided by line  20 . Switch  36  can be further configured to restart pump  30  in the event that the detected downstream temperature in line  20  falls sufficiently below a desired threshold setpoint temperature. However, this will only occur as long as one of relays  47 ,  50 ,  64 , and  80  is still detecting current flow associated with operation of the respective electrical appliance which would indicate a need for hot water recirculation through line  20 .  
         [0031]     According to one construction, thermal switch  36  is preferably placed adjacent hot water tank  38 , but is sufficiently spaced far enough away from hot water tank  38  so that switch  36  is not heated by tank  38 . For example, oftentimes hot water tank  38  is placed within a heated room. In such case, preferably thermal switch  36  is placed just outside such heated room in order to more accurately detect the true downstream temperature of water within line  20 .  
         [0032]     In operation, the downstream section of the return hot water line  20  will cool down much more slowly than the remaining hot water line  20  that serves the remaining upstream portion of the house. This is particularly true if the piping used to form hot water line  20  is present within a crawl space of the home. In the alternative, if thermal switch  36  is placed in a heated portion of the house, system  10  may not heat up water in the cooler downstream portion of line  20 . More particularly, the thermal switch (or temperature sensor)  36  that is present in the heated area will indicate a higher temperature than would be required by the setpoint temperature in order to trigger switch  36  to activate operation of pump  30 .  
         [0033]     System  10  provides one benefit in that there is no need for special switches or special wiring to be placed within a residential home or building at the time of construction. Instead, existing switches that are dedicated to other purposes, but which are associated with utilization of the respective hot water fixture, are monitored using a relay to detect current flow and to thereby trigger associated hot water recirculation for the respective hot water fixture. For the case of existing home or building construction, if existing wiring does not allow for appliances or light switches to be placed onto their own dedicated circuits, then a relay can be installed at the end of the circuit being used to detect and trigger hot water recirculation.  
         [0034]     As was shown with respect to bathroom  14  in  FIG. 1 , relay  64  is activated by a user turning on an overhead bathroom light. Alternatively, the relay can be used to detect current flow in an electrical wire for an overhead ventilation fan provided within the bathroom.  
         [0035]     For the case of kitchen  12 , relay  47  is activated by the use of overhead light switch  44 , which is placed adjacent to sink  40 . For the case of dishwasher  42  in kitchen  12 , relay  50  can be configured to detect current flow through electrical wire  50  that delivers power to the power circuit for the dishwasher  42 . Alternatively, relay  50  can be a solid state relay that is configured to attach directly to power circuitry for dishwasher  42 .  
         [0036]     Similarly, clothes washer  74  in laundry room  16  uses a similar relay  80  configured to detect current flow through electrical wire  82  that supplies power to power circuitry for clothes washer  74 . Alternatively, the solid state relay can be attached directly to power circuitry for the clothes washer in order to detect the turning on of power to clothes washer  74  at the initiation of a wash cycle. Further optionally, a switch can be provided when the door is opened on either of dishwasher  42  or washing machine  74  which sends an electrical signal that is detected by a relay and which initiates activation of the recirculation hot water pump  30  to start recirculation through line  20  upon opening of the respective door.  
         [0037]      FIG. 2  illustrates a preferred technique for detecting operation of an electrical circuit proximate a hot water fixture and associated with a user operating the fixture. More particularly, relays  46 ,  50 ,  64  and  80  are provided in association with electrical wires  47 ,  51 ,  63  and  82 , respectively, to detect current flow through the respective electrical wires. The detection of current flow indicates that a user has initiated operation of an electrical circuit proximate the respective hot water fixture. This signals a need to initiate hot water recirculation in line  20 .  
         [0038]     In the present case, relays  46 ,  50 ,  64  and  80  are mounted inside the housing of fuse box  88 , adjacent the respective fuses. Alternatively, relays  46 ,  50 ,  64  and  80  can be provided anywhere along the length of electrical wires  47 ,  51 ,  63  and  82  as they extend to the respective light switch or switch on the electrical device that is consuming power and for which hot water is needed.  
         [0039]     As shown in  FIG. 2 , relays  46 ,  50 ,  64  and  80  are shown installed within a main electrical panel of a fuse box  88 . Each relay comprises a current sensor that is wrapped around a power leg for a circuit that supplies power to an overhead light or power circuitry a dishwasher or a clothes washer. Depending on the electrical code for the area in which the system is being implemented, many devices can be run on one circuit, as is the case for the devices present within the bathroom  14  of  FIG. 1 .  
         [0040]     Also depending on the electrical circuit and the respective electrical codes in the region, a less expensive relay can be implemented without using a doughnut-type relay, but using a direct connection to an electrical contact of the respective electrical circuit. Accordingly, a solid state relay can be utilized.  
         [0041]     As shown in  FIG. 2 , all of relays  46 ,  50 ,  64  and  80  are tied into an electrical power supply wire  86  for pump  30 . When none of relays  46 ,  50 ,  64  and  80  detect power through the respective electrical wires,-all four relays are in an open position (as each relay acts as an on/off switch), which is configured to short out electrical wire  86  and cut off power supply to pump  30 . In the event that any one of the relays detects current flow through the respective electrical wires, the short in electrical wire  86  is shunted and power is delivered to pump  30  in order to operate pump  30  and initiate hot water recirculation to the system.  
         [0042]     According to one construction, a suitable relay comprises a current sensor-start/stop relay, such as a Model No. RIBXLCA, sold by Functional Devices, Inc., 310 S. Union Street, Russiaville, Ind. 46979. Such sensor is operative to detect both alternating current (AC) and direct current (DC). Another suitable relay, also sold by Functional Devices, Inc., comprises a Model No. RIBU1C. Alternatively, any of a number of doughnut-type solid state relays can be utilized. Further alternatively, mechanical relays (which are less expensive) may be suitable for certain applications, but can be susceptible to switch bounce, which makes them less desirable for applications requiring frequent changes of state. In addition to using a relay, any form of solid state switch that is capable of detecting current flow through an existing electrical circuit can be utilized to detect the need to initiate hot water recirculation.  
         [0043]     In compliance with the statute, the invention has been described in language more or less specific as to structural and methodical features. It is to be understood, however, that the invention is not limited to the specific features shown and described, since the means herein disclosed comprise preferred forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims appropriately interpreted in accordance with the doctrine of equivalents.