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FIELD OF THE INVENTION 
   The present invention relates to faucet systems, and more specifically to a faucet system designed to allow only cold water flow unless hot water flow is specifically requested. 
   BACKGROUND OF THE INVENTION 
   Faucets having a single handle for adjusting both water flow rate and water temperature are well known. In such faucets, the handle is lifted upward to adjust water flow, and is moved from side to side to adjust hot and cold water proportions such that a desired overall temperature is achieved. Generally, the handle has approximately 180 degrees of freedom, such that only cold water from a cold water source is dispensed when the handle is at its rightmost position, and only hot water from a hot water source is dispensed when the handle is at its leftmost position. When the handle is located between these two extreme positions, a mixture of hot and cold water is dispensed. 
   One problem with this type of single-handle faucet is that at least some water is drawn from the hot water source in every operative position of the faucet handle except the extreme right. As a result, even though the operator may require only cold water, if he or she lifts the handle without first moving it to the extreme right, or neglects to move the handle to the right after lifting, at least some hot water from the hot water source will be used. The amount of hot water wasted in a given water drawing incident will be directly proportional to the handle position and the duration of time the handle is not turned to the extreme right. The cumulative effect of multiple incidents of this type, as may occur, for example, when the operator is running a garbage disposal or rinsing dishes while loading a dish washer can be a substantial waste of energy. 
   Also, if drinking water is being drawn and the faucet handle is in any position other then the extreme right, at least some hot water will be drawn and consumed. This water may not be safe for consumption since it may have been stagnant in a sediment laden tank for a substantial amount of time. 
   The need has therefore arisen for a single handled faucet that draws water from a hot water source only if an operator specifically requests hot water and then functions as a conventional single handle faucet for the duration of use. 
   SUMMARY OF THE INVENTION 
   In order to prevent energy wastage associated with the inadvertent drawing of water from a hot water source in a faucet system, the present invention is directed to a system and method for dispensing only cold water from an outlet unless the operator performs an act that clearly indicates a conscious desire to draw hot water. The invention is additionally directed to methods of installing and using such a system. 
   The system comprises a faucet having a single handle, a hot water inlet, a cold water inlet, an outlet such as a spigot, and a mixing valve that is responsive to handle motion to control the flow rate of water out of the outlet and the proportion of hot and cold water dispensed from the outlet. Water flow to the hot water inlet of the mixing valve is controlled by a control valve coupled to both the hot water conduit and the cold water conduit. The control valve supplies cold water to the hot water inlet of the mixing valve unless the operator activates a switch or takes some other action clearly commanding hot water. 
   This design effectively reverses the role of the operator from consciously turning off hot water by moving the handle to consciously selecting hot water when actually desired. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Preferred exemplary embodiments of the invention are illustrated in the accompanying drawings, in which like reference numerals represent like parts throughout, and in which: 
       FIG. 1  is a top plan view of a faucet system constructed in accordance with a first embodiment of the invention; 
       FIG. 2  is a partially cut away front elevation view of the faucet system of  FIG. 1 ; 
       FIG. 3  is an exploded view of a mixing valve cartridge assembly and control plate of the faucet system of  FIGS. 1 and 2 ; 
       FIG. 4  is a cutaway top view of the control plate and switches; 
       FIG. 5  is a front elevation view of the faucet system of  FIG. 1 , illustrating an alternative power source; 
       FIG. 6  is a partially cut away front elevation view of a faucet system constructed in accordance with a second embodiment of the invention; 
       FIG. 7  is a cutaway side elevation view of the control valve of the faucet system of  FIG. 6 ; and 
       FIG. 8  is a view of the knob of the control valve taken along lines B—B in  FIG. 6 . 
   

   DETAILED DESCRIPTION 
   Construction of First Embodiment 
   Referring to  FIGS. 1 and 2 , a faucet system  10  constructed in accordance with a first preferred embodiment of the invention is coupled to a hot water source  12  and a cold water source  14  by conduits  16 ,  18 . The faucet system  10  includes a base  20 , a handle  27  mounted on top of the base  20 , and hot and cold water inlets  21  and  22  formed in the bottom of the base  20 . The inlets  21  and  22  are connected to a modified standard mixing valve  24  by internal passages or conduits (not shown). The inlets  21  and  22  are also supplied with water from standard lines  25  and  26 . 
   Mixing valve  24  is actuated by the handle  27  to allow a mixture of hot and cold water from inlets  21  and  22 , through spigot  28 , and to a common outlet  30 . Handle  27  has approximately 180 degrees of freedom, allowing a wide range of hot and cold water mixtures. At the extreme ends of the range of motion of handle  27  are “hot only” and “cold only” positions. The flow rate of water through the faucet system  10  can be varied from 0 (off) to maximum by raising the handle  27  from its lower most position to its uppermost position. All of the structures as thus far described are conventional. 
   In the present invention, system  10  is modified to include a cold water bypass  32 , a control valve  34 , and a switch assembly  36  for actuating control valve  34 . Referring now to  FIG. 2 , the control valve  34  of the first embodiment comprises a three way, two position solenoid valve having a single outlet  34   a  connected to the waterline  25  and first and second inlets  34   b ,  34   c  connected to the hot water supply conduit  16  and a cold water bypass line  32 , respectively. The control valve  34  is normally maintained in an “energy saving” position in which the valve outlet  34   a  is connected to the second valve inlet  34   c  cold water is isolated from the first valve inlet  34   b , hence preventing hot water from flowing from source  12  to hot water inlet  21 . The control valve  34  is selectively switchable to a “hot water supply” position in which the valve outlet  34   a  is connected to the conduit  16  and is isolated from the cold water bypass passage line  32 , hence permitting hot water to flow from the source  12  to the hot water inlet  21 . The control valve  34  is responsive to a switch which is actuated when the operator takes positive action to demand hot water. For instance, the switch could be actuated by a push button located on the handle  27 , the base  20 , or even an area adjacent the faucet such as on the countertop or sink. In the present embodiment, a switch assembly  36  is incorporated into the faucet system  10  and is responsive to movement of the handle  27 . It is preferably responsive to movement of the mixing valve  24 . Mixing valve  24 , as best seen in  FIG. 3 , is part of a standard faucet cartridge assembly  38 , in this case a cartridge assembly manufactured by Moen®. Assembly  38  is modified such that a bore  40  is drilled into its bottom to receive a post  41  bearing a switch control plate  42 . Switch control plate  42  bears a projection  44 . Control plate  42  is held in place within bore  40  via screw  46 , and control plate  42  rotates left to right and moves up and down along with the motion of an internal stem of cartridge assembly  38  as driven by handle  27 . 
   Referring again to  FIG. 2 , switch assembly  36  additionally includes a “hot water demand” switch  48  and a “return to energy savings” switch  50 . Each of these switches may, for example, be a proximity switch, though contact switches are shown in the drawings. As seen in  FIG. 4 , in the preferred embodiment, hot water demand switch  48  is located adjacent control plate  42  approximately 5 degrees forward from a rotational position of the cartridge assembly  38  corresponding to the “hot only” position of handle  27 . Hot water demand switch  48  is actuated by turning handle  27  almost all the way to its “hot request” position, at which point projection  44  contacts and activates switch  48 . The “return to energy savings switch”  50  is located adjacent control plate  42  just beneath plate  42  such that return switch  50  is actuated when control plate  42  is in its lowest position, i.e. when handle  27  has been depressed to turn off the faucet. 
   Switches  48  and  50  are both electronically coupled to a control module  52 , which is powered by a power transformer  54 . Power transformer  54  is supplied with household current in the conventional manner. As is typical of such modules, transformer  54  steps down the input AC voltage to reduced DC voltage and delivers the reduced DC voltage to control module  52 . The control module  52  preferably comprises a conventional integrated circuit (IC) control mode. 
   Alternatively, the transformer  54  could be replaced by a self-contained DC power source. One such source is illustrated in  FIG. 5  in the form of a battery pack  261 . Battery pack  261  is connected directly to the control module  52  and provides the power for actuating valve  34 . Battery pack  261  can be attached through a bore  263  in base  20  so that it is readily accessible when a battery (not shown) needs to be changed, and is provided with a cover  264 . Cover  264  preferably matches the rest of the external components of the faucet system  10 . 
   Referring again to  FIG. 2 , module  52  in turn actuates control valve  34 , which in the present embodiment is a solenoid valve, thereby allowing hot water to flow into hot water inlet  21  and closing off access to cold water bypass  32 . Once demand switch  48  has been activated, hot water from source  12  is allowed to flow through inlet  21  for as long as the user keeps lever handle  27  raised, regardless of the position of handle  27 . 
   An additional feature of control valve  34  is a manual override  56  for allowing water to be drawn from hot water source  12  in the event of an electrical outage or failure of the control module  52 . In the present embodiment, override  56  comprises a lever  58  that can be actuated to manually drive the control valve  34  to its hot water supply position. 
   Advantageously, the preferred embodiment also includes a timer feature that negates the need to repeatedly move the handle  27  to its leftmost position during periods of frequent use, as is often the case when a person is washing dishes. It is therefore desirable to allow an operator to draw hot water from faucet system  10  multiple times without having to make multiple specific hot water demands. A system which did not allow multiple draws of hot water in a single episode could become cumbersome and irritating, thus encouraging the user to manually override the system on a permanent basis and preventing the energy savings associated with use of the system. 
   In this embodiment, a timer  60  is interposed between return switch  50  and valve  34 , and preferably on the control module  52 . The timer  60  of this embodiment consists of a potentiometer (not shown) that is positioned in the control module  52  and that is responsive to closure of the switch  50  to enable switching of the control valve  34  from its hot water dispensing mode to its energy savings mode after a designated period of time. The designated time may be adjusted by turning a dial or screw  62  on the side of the control module  52  (seen schematically as  62  in  FIG. 2 ). The currently preferred embodiment of the timer  60  has a minimum of 2 minutes and a maximum of 5 minutes. During the set time period, any lift of handle  27  between the two extreme ends of the handle&#39;s range will draw both hot and cold water. The timer  60  will reset when the handle  27  is pushed down to close switch  50 , again preventing the control valve  34  from closing. As a result, the control valve  34  switches into its energy savings position only if the faucet is turned off and left in its off position for at least the designated period. 
   In normal use of system  10 , if an operator merely lifts handle  27  to obtain water without specifically requesting hot water, only cold water from cold water source  14  will be dispensed. In order to draw hot water, the operator turns handle  27  to the far left to activate the hot water demand switch  48 , and both hot and cold water from sources  12 ,  14  are provided as desired. The operator then adjusts the flow and temperature of the water as desired using handle  27  to control mixing valve  24  in the conventional manner. 
   When the operator no longer requires water, he or she lowers handle  27  to shut off the water, which has the additional effect of beginning a pre-set time period. If the operator does not lift handle  27  again within the pre-set time, the system  10  will reset to again provide only cold water when handle  27  is lifted. However, if the operator lifts handle  27  again before the pre-set time period expires, both hot and cold water from sources  12 ,  14  continue to be dispensed. 
   Construction of Second Embodiment 
   A second embodiment of the invention, shown in  FIGS. 6–8 , is similar in most respects to the first embodiment. The reference numerals shown are the same as for the first embodiment, incremented by 100, where corresponding parts are found. 
   As in the previous embodiment, a hot water demand switch  148  and a return to energy savings mode switch  150  are located adjacent to a control plate  142  and projection  144  borne by a modified cartridge assembly  138 . In this way, handle  127  of system  110  is able to effect switching of the control valve  134  between the hot water supply mode and energy savings mode. 
   However, in this embodiment, control valve  134  is not a solenoid valve. Referring to  FIG. 7 , it can be seen that valve  134  instead contains a cartridge  168  similar to the cartridge  138  containing mixing valve  124 . In order to use cartridge  168  effectively in valve  134 , hot water conduit  116  and cold water bypass  132  are arranged so that they connect with valve  134  opposite one another, as shown in  FIGS. 6 and 7 . A motor  170 , controlled by the control module  152 , turns the cartridge  168  within valve  134  all the way clockwise to allow hot water to be released through line  125 , or all the way counter-clockwise to prevent hot water from being disposed and to allow only cold water to flow through the valve  134  from bypass  132 . Hence, the valve  134  functions as a three-way, two position valve rather than a mixing valve. 
   System  110  also includes a manual override feature  156 , but in the present embodiment, override  156  consists of a knob  172  connected to the outer axial end of the cartridge assembly  168  by a screw  174 . In order to override system  110 , knob  172  is manually turned all the way clockwise to connect valve  134  to hot water conduit  116  and disconnect it from cold water bypass  132 . 
   Valve  134  of the present embodiment is also of somewhat simpler and of more durable construction than the solenoid version. The faucet system  110  of this embodiment is otherwise identical in construction and operation to the faucet system  10  of the first embodiment. 
   While the present invention has been described and illustrated in connection with preferred embodiments, the scope is not to be limited by such description and illustration, but is to be limited solely by the scope of the claims, which follow. It should be noted that features of the various embodiments may be combined and suitable equivalents may be substituted without departing from the scope of the present invention.

Summary:
A modified single-handled faucet is configured to permit the faucet to dispense hot water only if the operator actuates a hot water demand switch. The control valve couples the outlet of the faucet to the cold water source unless the operator actuates the hot water demand switch, and thereafter permits water to be dispensed from the hot water source, preferably via a conventional mixing valve that mixes hot and cold water in a desired proportion prior to dispensing the mixed stream.