Abstract:
An apparatus is shown for attachment to a plumbing system for the rapid on-demand delivery of hot water through the plumbing system to an ultimate point of use. The apparatus includes a diverter valve located in a hot water supply line upstream of the point of use. The diverter valve is actuated for a predetermined interval by a user to initially purge cold water from the hot water line to a drain. After the preset interval, the valve automatically closes. The initial diversion of cold water standing in the water supply line causes rapid delivery of hot water to the point of use once the diverter valve has completed its cycle.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to an apparatus and system for providing rapid hot water on-demand from a source, such as a water heater or boiler, to a point of use, such as the tap of a sink in a potable water system. 
     2. Description of the Prior Art 
     The present invention has application for homes, industrial or commercial buildings, or other structures having water lines which convey water from a source of hot water to an ultimate point of use, such as a kitchen or lavatory sink, a tub or shower, or other tap for dispensing hot water. Many existing structures have hot and cold water lines which discharge at a point of use with the discharge being controlled by a manual faucet in each line, or through a blending faucet common to both lines. The discharged water then passes down a discharge drain to the sewer system. In a typical residential, industrial or commercial installation, the water lines are contained in walls or flooring and distribute water to various commonly known discharge points. The water heater or boiler which supplies the hot water to the system is often located on the order of 10 to 150 feet or more from the various discharge points. 
     A common problem with potable water systems of the type described having an associated hot water source is that once the tap, valve or faucet controlling the flow of the water from the heated source is turned off, the water which is left in the line between the valve and the water heater or boiler gradually cools over time. The hot water line will lose heat in accordance with a number of variables, such as the nature of the conduit material conveying the water, the surrounding insulation, the temperature differential with the ambient surroundings, and the length of the line from the hot water source to the point of use where it is discharged. If a sufficient amount of time has elapsed before the hot water from that tap is again required, the user must wait until the cooled water within the line is evacuated through the lavatory drain and the hot water line is once again filled with hot water. The problem is usually worse in the case of large, single story homes, which tend to be more spread out than multilevel homes, where the water heater can be great distances from the farthest tap. A user may be forced to wait several minutes for the cooled water in the line to evacuate before hot water arrives at the tap location. The same process is repeated over and over during a typical day as water is allowed to cool again prior to repeated usage. 
     A number of different solutions to the above problem have been suggested in order to provide hot water rapidly at remote taps from the water heating device. One such solution is a recirculating system in which a return line is plumbed from the most remote tap back to the water heater source with a recirculating pump installed to provide a continuous flow of water. The flow ensures a supply of warm water contained in the plumbed line so that whenever the tap is turned on, warm water flows. There are a number of drawbacks with such a system, however. There is typically a relatively large up-front cost in installing such a system. It is usually necessary that the system be installed as a part of new construction. In other words, it is not easy to retrofit existing structures with circulating or recirculating systems. It is difficult or impossible to adequately insulate such systems in order to avoid unnecessary energy loss. In addition to the return line, an electrical pump is usually installed. The pump must be maintained and is subject to failures. In addition, there is an increase in electrical costs associated with the pump and the additional load on the water heater. 
     Another proposed solution for the problem of supplying rapid hot water is to provide a “point source” instant hot water device. Such devices are typically installed directly below the tap where the hot water is desired. The supplemental point source heating device is typically powered by an AC electric power source and is relatively expensive to install. The point source device usually has a small storage capacity of only a few gallons. The heat source is typically a resistance heating element, making such systems inefficient and expensive to operate in terms of relative energy costs. 
     Another more exotic solution to the problem is the so-called “convective circulating loop.” These type systems operate on the principal that in a closed recirculating flow loop, warm water will rise and cool water will fall, providing a continuous recharge of warmed water into the loop, from which taps and valves are operated. In this type system, a return loop segment is run from the farthest hot water tap back to the water heater. A venturi is typically provided to initiate flow, and a check valve is included to prevent back flow of water in the return line when the cold tap is operated. The plumbed return loop enters the cold water line just before the water heater device. However, there are also known drawbacks with the convective circulating loop type system. In order to operate, the return loop must be above the water heater. This generally limits the use of such systems to multi-story homes or buildings with the plumbing occurring above the level of the heated water source. If the system is installed in a typical one-story slab home with the potable water plumbing installed through the slab, then the necessary rise of warmed water and fall of cooled water will not take place. Another disadvantage of the system is the cost of running the return loop line in an existing home, typically limiting the application to professional plumbers. Again it is difficult to adequately insulate such systems and they tend to be relatively expensive from an energy point of view to operate. 
     To summarize, the most commonly used prior art systems, of the type described, are all relatively costly to purchase, install and operate in terms of energy costs. All typically require the services of a professional plumber for installation. The first two systems typically require an AC power source to operate, and the third system requires the plumbing to be above the heated water source to operate. 
     An object of the present invention is to provide a system for supplying rapid hot water on-demand at a point of use, which system is easy to install, relatively economical to purchase, and which can be operated from a DC power source, such as a battery source, if desired. 
     Another object of the present invention is to provide a system for supplying rapid hot water on-demand at a point of use, which system is easy to install, relatively economical to purchase, and which can be operated from an AC power source if desired. 
     Another object is to provide such a system which does not require that the presence of a return loop which is located at an elevation above the level of the heated water source. 
     Another object of the invention is to provide a system for supplying rapid hot water on-demand at a point of use where the system can be easily installed, for example, at a location below a lavatory sink associated with a discharge tap using simple tools and with a minimum of trouble or expense. 
     Another object of the invention is to provide such a system which can be easily installed by a homeowner without the necessity of employing a professional plumber. 
     Another object is to provide such a system which can be easily and economically installed by a home builder during new home construction, including hard wiring the system for AC power, in order to provide rapid hot water in the home with little additional expense to the ultimate home purchaser. 
     SUMMARY OF THE INVENTION 
     It is accordingly the general object of the present invention to provide a novel, rapid, hot water delivery method and apparatus to overcome the above-described limitations and other problems associated with the prior art devices for providing rapid hot water on-demand from a hot water source to an ultimate point of use. A hot water supply line is provided between the hot water source and the point of use within a structure. A diverter valve is installed within the hot water supply line upstream of the point of use for temporarily diverting cold water present in the hot water supply line to a drain to thereby purge cold water from the hot water supply line. The diverter valve has an open state and a closed state. The open state of the diverter valve can be set for a predetermined interval, the predetermined interval being directly related to a calculated heat loss for hot water being transferred over a known distance from the hot water source to the ultimate point of use within the structure. 
     Preferably, the diverter valve is selected from the group consisting of thermostatically controlled and electrically timed solenoid valves although other styles and types of valves could be utilized, if desired. The preferred diverter valve can be operated on either DC current, as where an existing structure is being retrofitted, or on AC current, as where a new structure is being hard wired during new construction. The predetermined interval of operation for the solenoid valve begins when a user presses a switch located proximate the point of use, whereby a controlled flow of cold water is diverted from the hot water line to thereby cause rapid delivery of hot water at the point of use when the timing cycle is complete. 
     In one embodiment of the invention, the system includes a wireless transformer for actuating the solenoid valve having an associated remote wireless switch. In this case, the predetermined interval for the solenoid valve begins when a user actuates the remote wireless switch. While a wireless switch provides convenience of installation, it is not necessary that the switching system be wireless. The switch can easily comprise a simple on/off switch which is wired into the circuitry of the solenoid valve and which is thrown by a user at the point of use to initiate the operation of the diverter valve. 
     The solenoid valve is preferably battery operated in cases where an existing structure is being retrofitted and no AC outlet is present at the point of use. The battery source can conveniently be selected from the group consisting of alkaline batteries, lithium-ion batteries, nickel cadmium batteries, nickel metal hydride batteries and rechargeable batteries of one or more of the above types. 
     The source of hot water in the system supplies water to the water supply line at an elevated temperature above ambient and wherein the timing cycle of the solenoid valve is set to supply hot water at the point of use at the same approximate temperature once the timing cycle is complete. The supply of hot water to the point of use occurs rapidly once the user has activated the diverter valve cycle with the switch located in proximity to the point of use. 
     Additional objects, features and advantages will be apparent in the written description which follows. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view, partly broken away, of a typical kitchen sink or bathroom lavatory having an apparatus of the invention installed thereon. 
         FIG. 2  is a simplified schematic illustrating the operation of the mechanical components of the system of the invention. 
         FIG. 3  is a view similar to  FIG. 2 , but illustrating one embodiment of the electrical components of the system of the invention in schematic fashion. 
         FIG. 4  is a view of the electrical panel and switch used in the system of the invention, in this case powered by a 12 volt DC power source, it being understood that other voltages could be used, as well. 
         FIG. 5  is a view of the mechanical components of the invention which are used with the electrical panel of  FIG. 4 . 
         FIG. 6  is a block diagram of the steps involved in the installation and use of the apparatus of the invention in supplying rapid hot water on-demand from the hot water source to the point of use. 
         FIG. 7  is a view of an alternate embodiment of the electrical panel used with the system of the invention, in this case powered by an AC power source. 
         FIG. 8  is a view of the mechanical components of the system of the invention used with the electrical panel of  FIG. 7 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Turning to  FIG. 1 , there is shown the general environment of the present invention.  FIG. 1  illustrates a sink  11  of the type found in a typical residential dwelling, or which could be found in a commercial building or industrial setting. While  FIG. 1  illustrates a kitchen sink, it will be understood that the method and apparatus of the present invention can be applied to a bathroom lavatory, or to a bathtub or shower installation or other facility of the same general type, assuming access to the necessary plumbing is available. When the term “sink” is used in this discussion, it is intended to encompass a sink, lavatory, bathroom tub, or shower, etc. 
     The sink shown in  FIG. 1  is conventional in nature and includes a pair of side-by-side basins  13 . A hot and cold water knob  15 ,  17  are mounted at the level of a counter top  19  and supply water to the common faucet  21 . 
     As illustrated in simplified fashion in  FIG. 1 , a water heater  23  has a hot water supply line  25  which communicates with a hot water conduit  27  under the sink which, in turn, supplies hot water through the valve and knob  15  to the common faucet  21 . The water heater  23  will be referred to as the “source” in the discussion which follows and the faucet  21  will be referred to as the “point of use.” While a traditional upright water heater  23  is shown in  FIG. 1 , it will be understood that the hot water source could be a boiler or other device for supplying potable water at an elevated temperature above ambient. A stop cock  29  is located in the hot water conduit  27  in order to turn hot water in the supply line  25  on and off for maintenance type operations. A separate cold water supply line communicates cold water through the conduit  31  to the valve knob  17  and the common faucet  21 . The sink also has a drain line  33  which is typically provided with a P-trap  35 . 
     The on-demand system of the invention for rapidly delivering hot water to a point of use can be adapted to the typical home plumbing arrangement illustrated in  FIG. 1 . Typically, the water heater  23  is located at some distance from the sink installation  11 . For example, if the water heater  23  is located near the kitchen plumbing, then the hot water supply line  25  might be required to traverse a distance of 100 feet or more to reach the lavatory sink in the bathroom of the dwelling. As mentioned in the background discussion, general heat transfer principles dictate that hot water will reduce heat in accordance with a number of variable in this type arrangement, which variables include such things as the type of hot water conduit material chosen, the surrounding insulation if any is present, the temperature differential with respect to the surrounding ambient conditions as well as the length of the hot water supply line from the hot water source to the point of discharge. 
     Generally speaking, the longer the line, the greater the area through which the heat may be transferred and the greater the heat loss. Such transfer of heat is typically more pronounced during the winter at which time there is a greater temperature differential between the hot and cold sides of the water supply system through which the heat is transferred. The periods of heat transfer loss are generally greatest during periods of non-use when the water stands in the hot water supply line. General principles of thermodynamics dictate that the heat transfer in the hot water supply line is in the direction that will establish equilibrium with the surrounding conditions of the line. 
     As a result of the above factors, a user of a water supply system such as that shown in  FIG. 1  will be subjected to the inconvenience of an initial cold flow of water through the hot water supply line  27 . The duration of the cold water flow again depends upon the various factors enumerated above and is primarily related to the distance at which the water heater  23  is located from the sink  11 . The greater the distance, the greater the heat loss and subsequent delay in receiving hot water from the tap of the faucet  21 . 
     Turning now to  FIGS. 2 and 3 , there is shown a simplified, schematic illustration of the operation of the components of the present invention.  FIG. 2  shows, in simplified fashion, a source of hot water, such as water heater  37 , which is supplied by a cold water inlet  39  through a check valve  41 . The source  37  communicates with the point of use  43  by means of a hot water supply line  45 . The supply line  45  communicates with a hot water faucet  47  through a hot water stop cock  49 . In a similar fashion, a cold water supply line  51  communicates cold water from the inlet  39  through a stop cock  53  to a cold water faucet  55 . 
     The system illustrated in  FIG. 2  also includes a T-element (approximately at  57  in  FIG. 2 ) which has an associated branch conduit  59 . The branch conduit  59  has a diverter valve  61  located therein. When the diverter valve  61  is opened, cold water initially present in the hot water supply line  45  is diverted through the branch conduit  59  to the drain  63 . 
       FIG. 3  illustrates the associated electrical components for the system illustrated in  FIG. 2 . In one embodiment, the electrical components simply comprise an electrical timer circuit  65  powered by a 12 volt DC power supply  67  for actuating the diverter valve, in this case electrically operated solenoid valve  69 . The solenoid valve has an open state and a closed state. The open state of the valve  69  can be set for a predetermined interval. The predetermined interval is directly related to a calculated heat loss for hot water being transferred over a known distance from the hot water source  37  to the ultimate point of use  43  within the structure. 
     While the preferred diverter valve  61  is selected from the group consisting of electrically timed solenoid valves and thermostatically controlled solenoid valves, it will be appreciated that other type valves could be used as well. For example, a screw controlled valve could be utilized. In one of the embodiments which follow, the solenoid valve  69  is operated on DC current. In another embodiment of the invention, the solenoid valve  69  is operated on AC current. 
     The predetermined timing interval for the solenoid valve  69  can be set to begin when a user presses a switch located proximate the point of use  43 . For example, note switch  71  in  FIG. 1  which is located in the counter top of the sink installation. The electrical switch  71  is wired within the power circuitry ( 67  in  FIG. 3 ) so that pushing the switch button actuates the timer  65 , opens the solenoid  69 , and causes a controlled flow of cold water to be diverted from the hot water line  45  to the drain  63  to thereby cause rapid delivery of hot water at the faucet  47  once the timing cycle is complete. 
     As will be described in the discussion which follows, the predetermined interval for the solenoid valve  69  can also be initiated by installing a wireless transformer for actuating the solenoid valve  69  with an associated remote wireless switch. In this case, the predetermined interval for the solenoid valve begins when a user actuates the remote wireless switch to divert the flow of cold water to the drain  63 . 
     As mentioned above, the system of the invention is an on-demand system for rapidly delivering hot water through a plumbing system to a hot water outlet.  FIG. 6  is a simplified block diagram illustrating the steps in determining the timing cycle for the solenoid valve to achieve speedy hot water. The timing cycle determines the interval during which the solenoid valve is in the “open state”, the interval being directly related to a calculated heat loss for hot water being transferred from the hot water source to the point of use. For example, the system would first be installed as explained with respect to  FIGS. 1–3 . The timer circuit  65  is first set at the minimal point, as determined by the particular manufacture of timer, generally about 3 seconds, as shown in the step  73 . When the hot water line is in the cold state, the user then presses the timing button in a step  74 , allowing water to run to the drain for 3 seconds. The discharge temperature at the hot water outlet is then manually checked in a step  75 . If the desired hot water temperature is not available, the timing button is pressed again, as in step  74 . The discharge temperature is again checked in step  75 . This operation is continued until the desired hot water temperature is available in step  77 . The user then calculates the “predetermined interval” that the valve is in the open state by multiplying the number of button presses times the 3 second interval to obtain a total number of seconds required to deliver the desired hot water temperature at the point of use. 
     In operation, the user then turns the stop cock ( 49  in  FIG. 3 ) off. The timer can now be set and checked without running any water. The stop cock  49  is then turned on. When the hot water line returns to its cold state, the user can press the timing button and the desired hot water temperature will be rapidly available. 
       FIGS. 4 and 5  illustrate a first embodiment of the components of the invention which utilize a DC power source. While a 12 volt DC power source is used to illustrate the invention, it will be understood that other DC power sources may also be commercially available and convenient to implement. For example, the power source may be 14.5 volt DC, 16 volt DC, 18 volt DC, etc. This version of the system of the invention can conveniently be utilized in existing homes or structures where an AC power outlet is not located proximate the hot water point of use. The components illustrated in  FIGS. 4 and 5  can be easily installed, for example, within the kitchen cabinet area illustrated in  FIG. 1 , by a home owner without the necessity of a plumber. Because the system operates on, e.g., a 12 volt DC power source, it is not necessary to install additional AC wiring or outlets. The mechanical components illustrated in  FIG. 5  include the hot water supply line  81  connecting the source  83  to the point of use faucet  85 . A commercially available stop cock  85  is located between the source  83  and point of use  85 . Most modern plumbing illustrates feature the stop cock  85  making the installation of the T-element  87  relatively easy. Installing the T-element within the hot water inlet  89  provides a branch conduit  91  for temporarily diverting cold water present in the hot water supply line  81  to a drain  93  to thereby purge cold water from the hot water supply line  81 . 
     An electrically operated solenoid valve  95  is located within the branch conduit  91 . The valve  95  can be switched between open and closed positions to allow water to be diverted through the branch conduit  91  to the drain  93 . The branch conduit  91  enters a drain entrance point  97  located below the sink  99 . Note that a downwardly inclined baffle  101  is located within the drain pipe  93  adjacent the entrance point  97  for directing the flow of cold water downwardly toward the drain  93 . 
     The electrically operated solenoid valve  95  is connected by a suitable wiring  102 ,  104  to the control panel  103  illustrated in  FIG. 4 . The control panel  103  includes as 12 volt timer  105  which is adjustable by means of the settings knob  107  between, for example, a 3 to 30 second timing interval. The commercially available 12 volt timing circuit  105  is powered by a suitable DC power source such as the battery pack  109 . Any number of battery sources can be utilized such as the typically available selection of alkaline batteries, lithium, ion batteries, nickel cadmium batteries and nickel hydride batteries and rechargeable batteries, for example. Because the low current requirement needed to operate the timer circuit  105 , a conventional battery pack  109  will normally last a number of months or even years without requiring replacement. Because the components illustrated in  FIG. 4  can be battery powered, it is not generally necessary to undergo the expense of installing a separate AC outlet underneath the sink  99 . As will be discussed further, however, an AC power source could be preferable if there is a 110 volt already present under the sink  99 . 
     The electrical control panel  103  of the system also includes a wireless transformer  111  for actuating the timing circuit  105 , and, in turn, the solenoid valve  95  by means of a remote wireless switch  113  which can be located in any convenient spot adjacent the point of use. The use of the wireless transformer  111  and remote wireless switch  113  eliminates the need to run unnecessary wiring or the need to cut unnecessary holes in counter tops or wall spaces adjacent the point of use. 
       FIGS. 7 and 8  illustrate an alternative wiring arrangement where an AC power source is adjacent the point of use. With reference to  FIG. 8 , the components utilized are the same as those discussed with reference to  FIG. 5  except than an AC powered solenoid valve  115  has been installed within the branch conduit  91 . Suitable wiring  117 ,  118  connects the solenoid  115  to the timing circuit  105 . In this case, rather than the wireless transformer  111 , a traditional on/off switch  119  is hardwired to the timing circuit  105 . The predetermined interval of the timing circuit  105  is initiated by a user pressing the button  120  of the on/off switch  119 . Otherwise, the operation of the system shown in  FIGS. 7 and 8  is identical to that system described in  FIGS. 4 and 5 . 
     It should be emphasized that the on-demand system of the invention supplies hot water at the point of use  43  which is generally of the approximate temperature of the hot water exiting the hot water source ( 37  in  FIG. 2 ). For example, if the water heater  37  supplies water to the water supply line  45  at a temperature above about 100° F., the timing cycle of the solenoid valve  63  will be set to supply hot water to the hot water outlet  47  at about the same approximate temperature once the timing cycle is complete. There are no recirculating loops are blending of the water supplies in order to supply “warm” water to the tap  47 . 
     An invention has been provided with several advantages. The on-demand hot water system of the invention is simple in design and economical to implement. The system does not involve the expense of a recirculating loop or require changes in elevation or other exotic elements. The hardware components of the system are commercially available from a variety of sources and are commonly known to those familiar with the electrical and plumbing trades. Because of the simplicity of the system, there is little to go wrong and maintenance requirements are minimum. 
     Because the system has a low current draw, it can be powered from a battery operated circuit and does not require the installation of AC outlet beneath the sink region of the sink region. Even with a water heater located, for example, 40 feet from the discharge point, hot water can easily be provided in 10 seconds or less using the apparatus and system of the invention. The water which is provided is at the approximate temperature of the hot water leaving the water heater. 
     While the invention has been shown in only one of its forms, it is thus limited but is susceptible to various changes and modifications without departing from the spirit thereof.