Abstract:
A combined domestic hot water supply and space heating system includes a single water heating system, one or more space heating systems and a heated fluid distribution apparatus. The apparatus has piping that provides communication between the apparatus, the water heating system, the space heating system, a fresh water source, and a house tap. The apparatus also includes anti-scalding device, a temperature and pressure gauge that monitors hot water temperature, a priority device that controls flows between the pipes and other safety and maintenance devices.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present invention is related to a system that provides both domestic hot water and space heating. More particularly, the invention is related to an apparatus that properly distributes heated water from a singe water heating system to domestic hot water and space heating applications.  
         [0002]     Most building or houses that require a domestic hot water supply as well as space heating use separate appliances for each purpose. For example, a conventional tank type gas water heater or an electric water heater has been used for domestic hot water supply. Conventional tank type gas heater or electric heater has disadvantage that it takes significant amount of space and it continuously lose heat energy due to its stand.  
         [0003]     Conventionally, when space heating is required, a separate furnace or any hydronic space heater has been used. The furnace or heater has its own gas burner or electric heating element. This scheme is inefficient and waste space and energy.  
         [0004]     A more compact and efficient hot water and space heating system has long been in need.  
       SUMMARY OF THE INVENTION  
       [0005]     An objective of the present invention is to provide a compact and efficient combined domestic hot water supply and space heating system.  
         [0006]     Another objective of the invention is to provide a fast, safe and reliable combined domestic hot water supply and space heating system.  
         [0007]     In order to achieve the above objectives, the present invention provides a combined domestic hot water supply and space heating system that includes a water heating system, a space heating system and a heated fluid distribution apparatus.  
         [0008]     The heated fluid distribution apparatus includes a cold water inlet fitting that is adapted to be connected to a fresh water source, a hot water outlet fitting that is adapted to be connected to a house plumbing fixture, a water outlet fitting that communicates with an inlet of the water heating system, a water inlet fitting that communicates with an outlet of the water heating system, a space inlet fitting that communicates with a space heating system return fitting of the space heating system, and a space outlet fitting that communicates with a space heating system inlet fitting of the space heating system.  
         [0009]     The water heating system may be an on demand flow through tankless water heater, or a fully modulating device, which can supply hot water at a predetermined temperature ranging from about 100° F. to about 180° F.  
         [0010]     The apparatus further includes an anti-scalding valve, which communicates with the cold water inlet fitting and the water inlet fitting and has an outlet that is connected to the hot water outlet fitting. The temperature of water from the anti-scalding valve is set to about 120° F.  
         [0011]     The apparatus further includes a temperature and pressure gauge that indicates incoming hot water temperature from the outlet of the water heating system.  
         [0012]     The apparatus further includes two three-way valves that change the combined domestic hot water supply and space heating system into a bypass mode in which the combined domestic hot water supply and space heating system is operated for providing domestic hot water to the house plumbing fixture.  
         [0013]     The apparatus further includes a priority device and a control board for prioritizing domestic hot water. The priority device is connected to the control board. The control board controls activation and deactivation of the three way valves. The control board is adapted to communicate with a house room thermostat for turning on/off of the space heating system.  
         [0014]     The apparatus further includes an expansion tank and an air separator between the water inlet fitting and the cold water inlet fitting. The expansion tank and the air separator balance pressure and automatically eliminate air in water flows between the water inlet fitting and the cold water inlet fitting.  
         [0015]     The apparatus further includes a thermostatic mixing valve, which communicates with the water inlet fitting and the space inlet fitting, and includes an outlet that is connected to the space outlet fitting.  
         [0016]     The apparatus further includes a circulation pump between the space inlet fitting and the water outlet fitting. The circulation pump provides water head that is high enough to activate a flow sensor for the water heating system. The circulation pump includes a check valve that prevents backflow from the water outlet fitting to the space outlet fitting.  
         [0017]     The apparatus further includes a space check valve that prevents cold water backflow to the space heating system, and a water check valve that prevents return water backflow to the cold water inlet fitting.  
         [0018]     The present invention utilizes an on-demand water heater, which is small enough to hang on a wall, as a water heating system. Sine the water heater has no reservoir tank, the water heater takes significantly less space compared to conventional water heater. Fully modulating computer controlled gas valve brings out significant energy saving. Automatic flow adjustment valve supplies hot water at desired temperature. Various sizes of input water heating system can be used anywhere.  
         [0019]     The present invention wisely controls conjunction of hot water supply and space heating with flow through type water heating system and space heating. Combining domestic hot water and space heating system involves a lot of confusion and difficulties in practice especially in controlling heat generation system, heated water temperature and flow rate.  
         [0020]     The present invention supplies and maintains potable domestic hot water at steady temperature, maximizes efficiency in output BTU in supplying hot water, and maximizes efficiency in space heating by optimized control for radiant floor heating system, base board heating system, or force air heating system with a single flow through water heating system. The single flow through water heating system adopts an on-demand tankless water heater or an instantaneous water heater.  
         [0021]     The present invention utilizes an open loop system and a semi-closed loop system simultaneously. The open loop system is used for domestic hot water supply, and the semi-closed loop system is used for space heating mostly.  
         [0022]     The present invention may be applied for various space heating system and wide area applications. For flow through water heating system that offers between 110,000 BTU/hour to 350,000 BTU/hour, the present invention can continuously produce hot water from 2 GPM to 12 GPM with 77° F. rise from ground water temperature. The present invention uses this hot water effectively to the combination of domestic hot water supply and space heating.  
         [0023]     The distribution apparatus is used for distributing heated water to potable domestic hot water supply and space heating with the single water heating system.  
         [0024]     The apparatus includes the priority device for supplying domestic hot water at 120° F., the step down mixing valve, the circulation pump for space heating, and safety and performance devices.  
         [0025]     The single water heating system is a flow through type, and has the inlet for replenishing the system with unheated water and the outlet for supplying heated water. The water heating system can be set to provide hot water at 100° F.˜180° F. depending on the space heating system.  
         [0026]     The space heating system includes a radiant in floor space heating, base board space heating and forced fan assistant space heating system. The temperature drop through the space heating system is designed to 14° F.˜35° F. on average using predetermined water flow rate and hot water temperature.  
         [0027]     Although the present invention is briefly summarized, the fuller understanding of the invention can be obtained by the following drawings, detailed description and appended claims. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0028]     These and other features, aspects and advantages of the present invention will become better understood with reference to the accompanying drawings, wherein:  
         [0029]      FIGS. 1   a  and  1   b  are perspective views of a heated fluid distribution apparatus for a combined hot water supply and space heating system according to the present invention;  
         [0030]      FIG. 2  is a schematic diagram showing the heated fluid distribution apparatus;  FIG. 3  is a schematic diagram showing the combined hot water supply and space heating system;  
         [0031]      FIG. 4  is a schematic diagram showing a water heating system; and  
         [0032]      FIGS. 5   a  and  5   b  are schematic diagrams showing space heating devices. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0033]      FIGS. 1   a  and  1   b  show a heated water distributing apparatus  32  according to the present invention.  FIG. 2  shows that the apparatus  32  has a cold water inlet fitting  21  for connection to a filtered and treated water source (not shown) as a potable fresh water source. The apparatus  32  also has a hot water outlet fitting  23  that delivers domestic hot water at a predetermined temperature, which is set about 120° F. The domestic hot water outlet fitting  23  normally supplies the household potable hot water via potable hot water taps or any plumbing fixtures that use potable hot water.  
         [0034]      FIG. 3  shows that the apparatus  32  has a water inlet fitting  24  that is connected to an outlet  2  of a water heating system  31 . The apparatus  32  has a water outlet fitting  22  that is connected to an inlet  1  of the water heating system  31  for replenishing unheated water. The water heating system  31  is an on demand flow through tankless water heater, and uses gas (Natural gas or Propane gas) or electricity. Alternatively, the water heating system  31  is a fully modulating device, which can supply hot water at a predetermined temperature ranging from about 100° F. to about 180° F.  
         [0035]     The cold water inlet fitting  21 , the water inlet fitting  24 , the water outlet fitting  22 , the hot water outlet fitting  23  of the apparatus  32 , and the inlet  1  and the outlet  2  of the water heating system  31  are made of ¾″ copper pipe and fittings.  
         [0036]     The apparatus  32  has a space outlet fitting  20  that is connected to a space heating system inlet fitting  27  or  29  as a heated water supply fitting, and a space inlet fitting  19  that is connected to a space heating return fitting  28  or  30  as a return conduit for reheating water. The space inlet fitting  19  and the space outlet fitting  20  of the apparatus are made of 1″ copper pipe.  
         [0037]     Referring to  FIG. 2 , the apparatus  32  has an anti-scalding device  9  for setting domestic hot water supply at 120° F. The anti-scalding device  9  is connected to the inlet fitting  24  and the cold water inlet fitting  21 , and it has an outlet that is connected to the hot water outlet fitting  23 .  
         [0038]     The apparatus  32  has a priority device  8  for prioritizing domestic hot water. The priority device  8  is connected to the control board  26 . The control board  26  controls activation and deactivation of three way valves  11 ,  15 .  
         [0039]     The apparatus  32  has a temperature and pressure gauge  7  that indicates incoming hot water temperature from the outlet  2  of the water heating system  31 . The temperature is between 100° F.˜180° F. depending on the temperature set in the water heating system  31 . The temperature and pressure gauge  7  is used to prevent high temperature replenish water.  
         [0040]     The apparatus  32  has an air separator  10 , an expansion tank  13  and a pressure regulator  12  for adjusting heated water pressure in space heating systems  33 ,  34  (refer to  FIG. 3 ).  
         [0041]     The apparatus  32  has a thermostatic mixing valve  17 , which has an inlet that is connected to the water inlet fitting  24 , and another inlet that is connected to the space inlet fitting  19 , and an outlet that is connected to the space outlet fitting  20  for supplying tempered hot water to the space heating system. As explained above, the space inlet fitting  19  is connected to the space heating return fitting  28  of the space heating system  33  or the space heating return fitting  30  of the space heating system  34 . The space outlet fitting  20  is connected to the space heating system inlet fitting  27  of the space heating system  33  or to the space heating system inlet fitting  29  of the space heating system  34 . The thermostatic mixing valve  17  keeps preset heated water supply temperature around 110° F. for the radiant space heating system  33  and above 140° F. for the forced air space heating system  34 .  
         [0042]     The apparatus  32  has a circulation pump  16  between the space inlet fitting  19  and the water outlet fitting  22  for circulating heated water in closed loop at the space heating system  33  or  34 .  
         [0043]     When temperature drops between the space outlet fitting  20  and the space inlet fitting  19  around 14° F.˜35° F. from the supply temperature depends on the space heating system  33 ,  34 .  
         [0044]     The circulation pump  16  provides water head that is high enough to activate a flow sensor  54  for the water heating system  31 . The circulation pump  16  includes a check valve  56  that prevents backflow from the water outlet fitting  22  to the space outlet fitting  20 .  
         [0045]     The apparatus further includes a space check valve  58  that prevents cold water backflow to the space heating system  33 ,  34 , and a water check valve  14  that prevents return water backflow to the cold water inlet fitting  21 .  
         [0046]     A house space heating thermostat  44  is connected to the control board  26  of the apparatus  32  for activating a space heating mode. When the space heating thermostat  44  is engaged to start, the control board  26  starts the circulation pump  16 , which circulates heated water through the space heating circuit. The temperature of circulated water is set around 110° F. for a radiant floor heating system, around 180° F. for a base board heating system. The heated water supply temperature is set above 140° F. for a forced air space heating system.  
         [0047]     The domestic hot water capacity is from 2 GPM to 10 GPM depending on the input rate of the water heating system  31 .  
         [0048]     The operation of the invention is explained. If there is a request for domestic hot water supply through the domestic hot water outlet fitting  23 , fresh cold water is supplied through the cold water inlet fitting  21 . Immediately after the cold water supply, the priority device  8  communicates to the control board  26 , and the control board  26  controls the three way valves  11 ,  15  to change to a bypass mode in which the whole system is operated for providing domestic hot water to household plumbing fixtures.  
         [0049]     If there is no request for domestic hot water supply, and a thermostat for house space heating sends request for heating, the whole system is operated only for space heating with semi-closed loop system until domestic hot water supply is requested.  
         [0050]     The room air temperature in the bypass mode may drop 2° F.˜10° F. from the room air temperature before the bypass mode is activated in about 20 minutes. The temperature drop depends on the heat insulation rate of the house.  
         [0051]     The apparatus  32  of the present invention with the single water heating system  31  and the space heating systems  33 ,  34  can satisfy most of domestic hot water requirements for traditional household plumbing fixtures. The relationship between the input capacity and hot water flow rate is explained under the predetermined temperature of 120° F. for the anti-scalding device  9 .  
         [0052]     Basic Equation for apparatus  32  that produces hot water as is, and in case that the hot water temperature of the water heating system  31  is set above 120° F. 
 
Input BTU×Efficiency (%)=500×GPM×ΔT 
        Where     Input BTU by BTU/hour     ΔT=preset temperature−fresh cold water temperature     GPM as gallons per minute        
 
         [0057]     Actual GPM with 120° F. can be predicted with the following equation: 
 
GH=(TM−TC)/(TH−TM) 
        Where     GH: Gallon of hot water requirement for one gallon of cold water     TM: Cold and hot water mixture temperature (The apparatus is set as TM=120° F.)     TC: Fresh cold water temperature     TH: Output hot water temperature in the water heating system        
 
         [0063]     The input BTU may be changed depending on each house&#39;s domestic hot water requirement and/or space heating requirement.  
         [0064]     While the invention has been shown and described with reference to different embodiments thereof, it will be appreciated by those skilled in the art that variations in form, detail, compositions and operation may be made without departing from the spirit and scope of the invention as defined by the accompanying claims.