Abstract:
A representatively pumpless water heater system has an instantaneous water heater coupled in series with a storage water heater by piping circuitry incorporating a fixed (and selectively fixed) bypass useable to route pressurized incoming cold water sequentially through the instantaneous and storage type heaters. The fixed bypass can also route pressurized incoming cold water to mix with the heated water exiting the instantaneous heater for delivery to the storage heater.

Description:
PRIORITY CLAIM 
       [0001]    This patent application is a continuation patent application of U.S. patent application Ser. No. 13/475,999, titled “FIXED (AND SELECTIVELY FIXED) BYPASS PUMPLESS COMBINATION INSTANTANEOUS/STORAGE WATER HEATER SYSTEM,” filed May 20, 2012, which claims priority to U.S. Provisional Patent Application No. 61/499,185, titled “FIXED (AND SELECTIVELY FIXED) BYPASS PUMPLESS COMBINATION INSTANTANEOUS/STORAGE WATER HEATER SYSTEM,” filed Jun. 21, 2011. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The present invention generally relates to liquid heating apparatus and, in representatively illustrated embodiments thereof, more particularly provides a specially designed, pumpless combination instantaneous/storage water heater system. 
         [0003]    The on-demand supply of hot water to plumbing fixtures such as sinks, dishwashers, bathtubs and the like has for years been achieved using fuel-fired or electric water heaters in which a relatively large water storage tank is provided with a fuel-fired burner or one or more electric heating elements controlled to maintain pressurized, tank-stored water at a selectively variable delivery temperature—typically around 120 degrees Fahrenheit. Pressurized cold water from a source is piped to the tank to replenish hot water drawn for supply to one or more plumbing fixtures operatively connected to the water heater. 
         [0004]    Another conventional way of providing an on-demand supply of hot water to various plumbing fixtures is to use a tankless or “instantaneous” water heater in which water is flowed through a high heat input heat exchanger, without appreciable water storage capacity, so as to provide only as much hot water as needed by the open fixture(s). Where higher hot water flow rates than the instantaneous water heater can provide at the desired heated temperature are required, it has been conventional practice to connect a storage tank to the instantaneous water heater, in series, to augment the hot water delivery capability of the instantaneous water heater with pre-heated storage tank water. 
         [0005]    According to another conventional practice, a hot water recirculating loop with a circulating pump therein is operatively coupled to one or both of the instantaneous heater and storage tank to provide even faster delivery of hot water to the served fixtures. Despite the overall hot water production and delivery improvements provided by these conventional instantaneous/tank type water heater combinations, they present several well-known problems, limitations and disadvantages. 
         [0006]    For example, the necessity of providing a pump and the pump&#39;s necessary controls undesirably builds in additional cost and complexity to the overall hot water supply system. 
         [0007]    It would thus be desirable to provide an improved combination instantaneous/tank type water heater system in which the attendant complexity and cost, of pumps, mixing valves and controls was eliminated or minimized. 
       SUMMARY OF THE INVENTION 
       [0008]    In carrying out principles of the present invention, in accordance with representatively illustrated embodiments thereof, specially designed, representatively pumpless fluid heating apparatus is provided which comprises an instantaneous fluid heater, a fluid storage vessel, and flow circuitry, interconnected between the instantaneous fluid heater and the fluid storage vessel. Via the flow circuitry an incoming fluid may be sequentially flowed through the instantaneous fluid heater and the fluid storage vessel or through a fixed (or selectively fixed) bypass to mix with the heated water exiting the instantaneous heater for delivery to the storage heater for discharge from the apparatus as heated fluid. 
         [0009]    The flow circuitry, which is representatively piping interconnecting the instantaneous fluid heater in series with the fluid storage vessel, has incorporated therein (1) an incoming fluid bypass structure, representatively a bypass pipe, operable to cause a fixed portion of the incoming fluid to bypass the instantaneous fluid heater, and (2) an orifice connected in series with said incoming fluid bypass pipe and operable to blend a fixed amount of the bypassed fluid and heated fluid exiting said instantaneous fluid heater to maximize the temperature of heated fluid entering the fluid storage vessel while minimizing the pressure loss through the entire system. 
         [0010]    The flow circuitry may incorporate therein instead of the orifice, a mixing valve, operable to receive heated fluid exiting the instantaneous fluid heater and unheated fluid through the bypass pipe to deliver to the fluid storage vessel at a fixed temperature. 
         [0011]    The flow circuitry may further incorporate therein instead of the orifice, a solenoid valve, operable to control whether unheated fluid will pass through the bypass pipe and mix with the water exiting the instantaneous fluid heater before entering the fluid storage vessel. The opening and closing of said solenoid valve can be controlled by (1) a thermostatically controlled electrical switching device placed in a position to measure the temperature of the fluid entering the fluid storage vessel, (2) an electrical relay triggered by the signal of a flow sensor or flow switch that is internal to the instantaneous fluid heater, or (3) a flow switch in line previous to the bypass pipe. 
         [0012]    Illustratively, the fluid heating apparatus is a water heating apparatus, with the instantaneous fluid heater being a fuel-fired instantaneous type water heater, and the fluid storage vessel being the water storage vessel being the tank portion of a storage type water heater having an electrical heating section used to selectively add heat to water disposed within the tank. However, the system described herein is not limited to water heater heating and may be advantageously employed with a variety of other types of fluids to be heated. 
         [0013]    Preferably, the combination instantaneous/storage type fluid heating apparatus of the present invention is of a pumpless construction. However, if desired, a pumped fluid recirculation system could be suitably incorporated into the apparatus without departing from principles of the present invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]      FIG. 1  is a schematic diagram of a specially designed pumpless, combination instantaneous/storage water heating system embodying principles of the present invention. 
           [0015]      FIG. 2  is a schematic diagram of an alternate embodiment of the  FIG. 1  system. 
           [0016]      FIG. 3  is a schematic diagram of an alternate embodiment of the  FIG. 1  system. 
           [0017]      FIG. 4  is a schematic diagram of an alternate embodiment of the  FIG. 1  system. 
           [0018]      FIG. 5  is a schematic diagram of an alternate embodiment of the  FIG. 1  system. 
       
    
    
     DETAILED DESCRIPTION 
       [0019]    Schematically depicted in  FIG. 1  is a pumpless water heater heating system  10  that embodies principles of the present invention and includes an instantaneous gas water heater (IGWH)  12  having a burner section  14  supplied with gaseous fuel via a gas supply line  16 , and a storage type water heater (SWH)  18  having a water storage tank  20  with electric heating elements  22  extending into the interior of tank  20 . IGWH  12  has a water inlet  24 , and a water outlet  26 , and tank  20  has a water inlet  28  and a water outlet  30 . 
         [0020]    A water line  34  is interconnected between the IGWH inlet  24  and the tank inlet  28 , and a water line  38  is interconnected between the IGWH outlet  26  and the tank inlet  28  and extends from the tank inlet  28  downwardly through the interior of the tank  20  to a bottom portion thereof. Valve  36  is operatively connected as shown in the water line  34 . Valve  36  is a bypass valve controllable to allow a selectively variable flow or an orifice to allow a fixed amount of incoming cold water therethrough via the line  34  in the direction of the arrows in line  34 . A cold water inlet line  32  (through which incoming cold water is flowed to the system) is connected as shown in the line  34  between the IGWH inlet  24  and the valve  36  as shown. 
         [0021]    During a demand for hot water supply from the system  10 , pressurized hot water at temperature T TANK  is discharged from the tank outlet  30  to the open fixture(s) served by line  42  while at the same time pressurized cold water, at temperature T COLD , from a source, is flowed through line  32  into the segment of the line  34  between the IGWH outlet  26  and the bypass valve  36 . A portion of this incoming pressurized cold water is flowed into the through IGWH  12  and discharged therefrom, into the line  38 , as heated water, at temperature T HOT . The balance of the incoming pressurized cold water bypasses IGWH  12  and flows through the valve  36  into the line  34  where it mixes with line  38  to become T MIX , which flows into the interior of the tank  20  via line  40 . 
         [0022]    As needed (for example during standby periods of the system  10 ), the electric heating elements  22  may be energized to maintain T TANK  at an appropriate level. 
         [0023]    It is important to note that the unique use of the cold water bypass valve  36  in the overall interconnecting flow circuitry of the system  10  advantageously permits full flow from tank  20  while allowing a constant volume of T MIX  into the tank inlet  28 . 
         [0024]    The selective bypassing of cold inlet water around IGWH  12  helps reduce pressure loss and limited flow in the heat exchanger portion of IGWH  12 . The bypass ratio of valve  36  may be fixed or adjustable with respect to the outlet temperature T HOT . 
         [0025]    As previously mentioned herein, system  10  efficiently functions without the expense of a pump and its associated recirculation piping (although such a pump and associated recirculation piping could be appropriately added to the system if desired). Instead, the “driving” force selectively flowing the tempered water to the plumbing fixture(s) via pipe  42  is simply the pressure of the cold water source coupled to the pipe  40 . Additionally, the combination system  10  is provided with improved hot water supply from Tank  18  due to the provision of the cold water bypass valve  36  in the piping circuitry interconnecting IGWH  12  and SWH  18 . 
         [0026]    An alternate embodiment  10   a  of the previously described pumpless water heating system  10  is schematically depicted in  FIG. 2 . System  10   a  is identical to system  10  with the exceptions that (1) valve  36  is replaced with a mixing valve, representatively a thermostatically controlled mixing valve  46 . . The mixing valve  46  allows cold water from line  32  to bypass IGWH  12  and mix with T MIX  from line  38  and flow into tank  20  as T MIX  through line  40 . This feature provides for substantially improved temperature control of T MIX  by providing a controlled mix of T COLD  from line  32  and T HOT  discharged from IGWH  12 . 
         [0027]    An alternate embodiment  10   b  of the previously described pumpless water heating system  10  is schematically depicted in  FIG. 3 . System  10   b  is identical to system  10  with the exceptions that valve  36  is replaced with a thermal switch (ie “Aquastat)  48  and a normally closed solenoid valve  50 . The thermal switch  48  allows cold water from line  32  to bypass IGWH  12  and mix with T HOT  from line  38  and flow into tank  20  as T MIX  through line  40 . 
         [0028]    This feature allows for better utilization of the IGWH  12  during low usage (flow) periods by eliminating unnecessary amounts of T COLD  into tank  20 . During high usage (flow) periods, T HOT  from 
         [0029]    IGWH  12  will decrease below the set temperature of thermal switch  48  thus activating solenoid  50  to provide a greater volume of T MIX  into tank  20 . 
         [0030]    An alternate embodiment  10   c  of the previously described pumpless water heating system  10  is schematically depicted in  FIG. 4 . System  10   c  is identical to system  10   b  with the exceptions that thermal switch  48  is replaced with a flow sensor  52  and a relay  54 . The flow sensor  52  sends a signal to relay  54  when a predetermined amount of flow is passing through IGWH  12  to activate solenoid valve  50 . Flow sensor  52  can be integral to IGWH  12  or installed in lines  32 ,  38 , or  40 . This feature allows for an alternate means to detect heavy usage (flow) periods based on flow conditions rather than temperature conditions. As previously mentioned in alternate embodiment  10   b,  solenoid  50  will only activate during high usage (flow) periods in order to make best utilization of IGWH  12 . 
         [0031]    An alternate embodiment  10   d  of the previously described pumpless water heating system  10  is schematically depicted in  FIG. 5 . System  10   c  is identical to system  10   b  with the exceptions that thermal switch  48  is replaced with flow switch  56 . The flow switch  56  sends a signal to solenoid valve  50  when a predetermined amount of flow is passing through line  32 . This feature allows for a direct signal to solenoid  50  without the use of additional electronics as describe in alternate embodiment  10   c.  As previously mentioned in alternate embodiment  10   b,  solenoid  50  will only activate during high usage (flow) periods in order to make best utilization of IGWH  12 . 
         [0032]    In any of alternate embodiments  10   a,   10   b,   10   c  and  10   d,  valve  36  as shown in  FIG. 1  could be added to line  32  to provide a fixed amount of the incoming fluid to bypass IGWH  12 . As can be readily seen from the foregoing, the representatively illustrated embodiments  10 , 10   a,   10   b,   10   c,   10   d  of the pumpless water heater system of the present invention, compared to conventional combination instantaneous/tank type water heater systems, provide improved water temperature and flow rate control, while at the same time eliminating the complexity and cost of an associated mechanical pumping system. 
         [0033]    While the pumpless systems  10 , 10   a,   10   b,   10   c,   10   d  illustrated and described herein are representatively water heating systems, principles of the present invention are not limited to water heating but could be alternatively employed to advantage in conjunction with supply systems for other types of fluids. Additionally, while as previously mentioned herein the systems  10 , 10   a,   10   b,   10   c,   10   d  are representatively of pumpless configurations, various types of pumps and associated recirculation systems could be appropriately incorporated therein if desired. 
         [0034]    In yet a further alternative embodiment, the flow circuitry described herein may be disposed within a self-contained unit that can be operably integrated such that an instantaneous fluid heater could be connected to any fluid storage vessel. 
         [0035]    The foregoing detailed description is to be clearly understood as being given by way of illustration and example only, the spirit and scope of the present invention being limited solely by the appended claims.