Patent Publication Number: US-2012043389-A1

Title: Apparatus for automatically controlling a constant flow by considering a heating load the specification of which

Description:
TECHNICAL FIELD 
     The present invention relates to an apparatus for automatically controlling a constant flow by considering a heating load, which calculates the amount of heat required for the optimum heating of each room by considering heating loads for each room, discovers the optimum flow value in proportion to the calculated amount of heat, and reduces the total flow value of the household by the optimum flow value corresponding to the room for which heating is stopped, to thereby reduce fuel costs in proportion to the saved flow value, and to decrease noise of a tube due to caviation. 
     BACKGROUND 
     A heating system used in an apartment house or a large building may include an individual heating system which uses the fluid heated by a heat source such as a boiler separately installed on a individual household, and a communal heating system which uses the fluid heated by a heat source installed outside a household and supplied to individual household wherein the communal heating system includes a central heating system which uses a heating source such as a central boiler installed inside an apartment house belt or a large building and a regional heating system which uses a heating source such as a regional power plant outside the apartment house belt. 
     In these heating systems, water may be generally used as a heating medium and specially the communal heating system may be provided with a circulation system which is configured for circulating warm water such that the warm water heated through a heating source is supplied from a central supply tube to a supply tube branched to the respective household and then the warm water is supplied for heating the respective household through a warm water distribution device installed on each household and including a warm water supply header, a plurality of warm water duct, a warm water returning header and a water returning header, and thereafter the warm water which is supplied through the water returning pipes of the respective household is collected to a central water returning tube and returned to the heating source. 
     In a prior warm water distribution device, as described in Korean Utility Model registration No. 371794, which was filed by the same applicant as this application, a constant flow valve is provided on a water returning pipe connected to a warm water returning header to limit a total constant flow per household and the total constant flow is a summation of flows in the water returning pipe flowing the respective room. 
     At this time, a driver may be provided on the respective water returning pipe and thus the returning pipe is opened and closed depending on a setting temperature of each room and thereby to maintain a constant temperature at each room. 
     However, in the prior warm water distribution device as described above, when a total constant flow of a constant flow valve is once set when the constant flow valve is installed, it cannot be re-set to change the total constant flow and thus the setting constant flow may flow through the constant flow valve, and as a result even though the room not necessary to be heated is closed by the driver, much more flow than the setting flow to be originally flowed flows further rapidly through a water returning pipe installed in another room being heated. (Referring to a formula, flow (Q)=sectional area×flow velocity (AV). As a result, in consideration of the water returning pipe which is now heating a room even though the flow increases, a flow velocity is great and thus sufficient heat is not exchanged between a room and a fluid not to save a heating cost though heating area decreases, and thereby to decrease a heating efficiency. 
     Specially, when more than one room stop being heated, as the flow velocity increases in the water returning pipe which is heating a room, a cavitation (cavity phenomenon) occurs to induce a water hammering phenomenon in which when a fluid flows, the fluid hammers an inner side of the pipe, thereby to make a noise. 
     Furthermore, in another warm water distribution device, as described in Korean Patent Registration No. 635107, a differential pressure flow adjusting valve is provided for constantly maintaining a differential pressure between a supply pipe and a water returning pipe based on a fluid pressure difference inside the supply pipe and the water returning pipe. 
       FIG. 1  is a block diagram showing a prior warm water distribution device provided with a prior differential pressure flow adjusting valve. 
     As shown in  FIG. 1 , the warm water distribution device includes a warm water supply header  3  connected to a supply pipe  2  branched from a center supply pipe  1 , a plurality of warm water ducts  4  branched from the warm water supply header  3  to each room and supplying heat thereto, a water returning pipe  5  which is communicated with the respective warm water duct  4 , a warm water returning header  6  to which the plurality of water returning pipes  5  are connected in a one point, a water returning pipe  7  to which the water returning header  6  is connected, and a central water returning pipe  8  to which the water returning pipe  7  is connected in a one point. 
     Herein, a differential pressure flow adjusting valve  10  to be operated by a fluid pressure difference between a water returning pipe  7  and a supply pipe  2  may be provided on the water returning pipe  7  so that when one room is closed by the driver  9 , the fluid velocity toward another room may not increase. 
     However, since the differential pressureflow valve  10  is operated mechanically by using a difference pressure, a total constant fluid is not controlled actively and also flow is not controlled properly, and further since a constant fluid of a fluid actually flowing through the differential pressureflow adjusting vale cannot be known, a constant flow valve has to be provided separately. 
     Furthermore, since a total constant fluid for a household is not controlled properly in proportion to the heating-stop rooms, the heating efficiency decrease and noise caused from cavitation, which are initially mentioned, are confirmed to remain from experimental results when one or more rooms are heating-stopped. 
     As a result, recently, a heating device has been introduced to save fuel cost and prevent fluid velocity increase and thus pre-avoid cavitation occurrence, in which one room is heating-stopped, a controller senses the heating stop and allows the flow adjusting valve to reduce the total constant fluid by the amount of the fluid flowing through the heating-stop room. 
     The controller in the heating device controls a flow value of the flow adjusting valve according to the following two methods. 
     According to the first method, a controller senses whether a driver of branch pipe valve is opened and closed, calculates “open valve number rate” which refers to a number rate of open branch pipe valve among a total branch pipe valve numbers, and uniformly controls the flow adjusting valve as the flow corresponding to the open branch pipe valve number. 
     According to the flow control method by calculating the “open valve number rate”, for example in case of a house having 4 rooms, when 2 room indoor temperatures reach a desired temperature and thus 2 drivers among 4 drivers are closed, it is controlled to uniformly supply 50 flow, assuming that a total constant fluid is 100. The flow control method may be applied to rooms having same area and same heating load. However, since the rooms practically have different area and have different heating load even in case of having same room area, the request heating amounts necessary for heating the rooms (hereinafter, referred to as “necessary request heating amount”) are different from each other and thus an error greatly becomes larger when uniformly controlling the total constant fluid by the valve open number of a driver. As a result, an optimum heating cannot be performed and further over-flow or low-flow of a fluid may be made into a room in which a driver is opened, thereby to produce cavitation and decrease the heating efficiency. 
     Meanwhile, according to the second method, in consideration of a branch pipe length in proportion to a room area, the controller senses the opened branch pipe valves all, calculates a branch pipe open length value by summating all the respective lengths of the warm water branch pipes on which the opened branch valves are installed, calculates the “open valve length rate” which refers to the branch pipe open length value among a branch pipe total length value made by summating the respective length values of a total warm water branch pipes, and controls the flow adjusting valve as the flow value corresponding to the open valve length rate. 
     The control method according to the open valve length rate is a further advanced control method and is performed by considering actually different room sizes, comparing with the control method according to the open valve number rate. However, the control method by the open valve length rate neglects the facts of rooms having different heating loads even in case of same area and thus the flow is not supplied enough to provide the necessary request heat amount of the corresponding room. 
     For reference, even in case of same room area, the heating loads for the room may be different when considering the numbers of windows provided in the room and whether the room is fabricated with external walls through which heat is exchanged sufficiently with outer air, which causes different loss heating amounts, and thus the necessary request heating amounts for an optimum heating may be different. 
     That is, even though a conceptual approach has been made about the total constant fluid control in the heating device and thus the total constant fluid seems to be controlled effectively, the heating load which is an important factor when designing the heating system is not considered at all and thus a fluid supply proper for the necessary request heating amount depending on different heating load is not made. Accordingly, as shown in a comparison table to the present invention, which will be described later, the optimum heating system is not implemented due to the wide range of error between the necessary request heating amount and the supplying flow. 
     Since the heating load is not considered at all while installing the heating device in a house, the standard of “indoor supply temperature−indoor water returning temperature=15° C.” as a regional heating design criteria is not satisfied. 
     The design criteria has to be met for installing a heating device wherein the Korea Housing Corporation design criteria  99  page, 2009 is the followings. 
     2) Regional heating criteria
         a) Temperature condition   (1) first side supply temperature: 115° C.   (2) first side water returning temperature: 50° C.   (3) indoor supply temperature: 60° C.   (4) indoor water returning temperature: 45° C.   (5) external air temperature: applying to the external temperature of the corresponding region of the energy save design criteria for a building   (6) indoor temperature: 20° C.   b) pipe design   (1) temperature for calculating flow   (i) heating water (first side): t 1 =115° C., t 2 =50° C.   (ii) heating water (second side): t 1 =60° C., t 2 =45° C.   (iii) hot water service (first side): t 1 =75° C., t 2 =40° C.   (2) pipe diameter   (i) pipe friction resistance: first side: 200 mmAq/m
           second side: 10 mmAq/m   
           (ii) fluid velocity: less than 1.5 m/s   (iii) pipe diameter selection (first side): according to “the heating load criteria per pipe diameter table” of Korea regional heating corporation   (iv) pipe diameter selection (second side): referring to X chapter, 13-13 water flow table       

     Herein, the indoor supply temperature has to be 60° C. and the indoor returning water has to be 45° C. wherein even though warm water is supplied at 60° C., the indoor returning temperature cannot be 45° C., without considering the heating load, which may be caused from large variation of heat loss depending on the heating load and. The heating device installment not meeting the design criteria is decided not to be proper. 
     DISCLOSURE 
     Technical Problem 
     The present invention has been proposed to solve the drawbacks and an object of the present invention is to provide an apparatus for automatically controlling a constant flow by considering the heating load in which a total constant flow per household is actively and proportionally controlled, corresponding to whether each room is heated and not heated, and in a case where some rooms are not heated, a total constant flow is reduced by as much as flow flowing the rooms eventually to save heating cost by increasing heating efficiency and solve noise problem due to cavitation. 
     Another object of the present invention is to provide an apparatus for automatically controlling a constant flow by considering the heating load in which when a total constant flow is controlled, corresponding to whether a room is heated and not heated, the total constant flow is controlled to reduce by as much as the necessary request heat amount for each room thereby to always maintain an optimum heating. 
     Technical Solution 
     In order to achieve the above object, the present invention provides an apparatus for automatically controlling a constant flow by considering heating load, comprising: a supply tube through which ware water is supplied to each household; a warm water duct which is communicated with the supply tube and is branched to each room, and allows the latent heat of the warm water to be heat-exchanged with the corresponding room; a water returning pipe which is communicated with the warm water duct and to which the heat exchanged warm water is returned; a water returning pipe to which flows of the water returning pipe is collected and through which the collected flows are discharged outside; a temperature adjusting portion which is installed in each room to set a desired temperature thereto and measures an indoor temperature of each room; a driver which is installed respectively in the water returning pipe and opens and closes a passage of the water returning pipe according to an electrical signal; a variable flow valve which is installed in the supply tube or the water returning tube and varies the flow of the supply tube or the water returning tube according to another electrical signal; and a controller which receives the signal from the temperature adjusting portion and controls the driver and the variable flow valve wherein the controller in which an optimum flow value in proportion to a necessary request heat amount of the corresponding room in consideration of heating load per room is stored, controls the driver of the room where heating has to be stopped, according to a signal from the temperature adjusting portion to close a passage of the water returning pipe of the corresponding room, thereby to reduce a flow of the variable flow valve in proportion to a ratio of the optimum flow value of the closed room to a summation of a total optimum flow value. 
     Here, the heating load to be stored in the controller is obtained by summating all “face load amount” on the respective face forming the room wherein the face load amount is obtained by multiplying at least one factors among “heat transmission rate, area, azimuth coefficient, and relevant temperature difference”. 
     The variable flow valve according to a first embodiment comprises: a body in which a fluid path through which an entrance and an exit are communicated is provided and in which a sheet is formed between the entrance and the exit with decreasing a sectional area of the fluid path; a chamber in which a hydraulic pressure passage is formed in one inner side of the body, which is applied by the entrance side hydraulic pressure and the exit side hydraulic pressure; a diaphragm which partitions the chamber and is applied both sides by the entrance side hydraulic pressure and the exit side hydraulic pressure, and is deformed by the pressure difference of the entrance and the exit; a moving body which is connected to one side of the diaphragm and is resiliently installed to adjust a sectional area passing from the sheet toward the exit by the pressure difference in the chamber; and an actuator which adjusts on the other side of the body an opening amount of the sheet by a control signal from the controller. 
     At this time, the moving body comprises: a head portion which is connected to the diaphragm; a stem portion which is extended from the head portion toward the sheet and adjusts a sectional area of a flow passing from the sheet toward the exit; and a resilient member which is installed between the moving body and the chamber so that the moving body is returned when pressures of both sides are equal based on the diaphragm. 
     The variable flow valve according to a second embodiment comprises: a body in which a fluid path through which an entrance and an exit (are communicated is provided and in which a sheet is formed between the entrance and the exit with decreasing a sectional area of the fluid path; a chamber in which a hydraulic pressure passage is formed in one inner side of the body, which is applied by the entrance side hydraulic pressure and the exit side hydraulic pressure; a diaphragm which partitions the chamber and is applied both sides by the entrance side hydraulic pressure and the exit side hydraulic pressure, and is deformed by the pressure difference of the entrance and the exit; a moving body which is connected to the diaphragm and moves to reduce a flow sectional area of an inflection portion passing from the entrance side toward the sheet side when a pressure in the sheet side is greater than that in the exit side; and an actuator which adjusts an opening amount of the sheet by a control signal from the controller. 
     At this time, an outer peripheral surface of the diaphragm is fixed to an inner wall of the chamber and on an inner peripheral surface of the diaphragm a through portion to which the moving body is connected is formed. 
     Further, the moving body comprises: a head portion which is fitted into the through portion of the diaphragm; a stem portion which is extended from the head portion to the inflection portion through which the entrance side and the sheet side are communicated to adjust a sectional area of a flow passing through the inflection portion according to a deformation of the diaphragm; and a resilient member which is installed on the moving body so that the moving body is returned when pressures of both sides are equal based on the diaphragm. 
     Furthermore, an adjusting screw is provided in the inflection portion to adjust initially passing flow by adjusting an interval from the step portion. 
     The variable flow valve according to a third embodiment comprises: a body in which a fluid path through which an entrance and an exit are communicated is provided and in which a sheet is formed between the entrance and the exit with decreasing a sectional area of the fluid path; a flow sensor which is installed on the fluid path and measures a flow of a fluid passing the fluid path; and an actuator which adjusts an opening amount of the sheet by a control signal from the controller. 
     Here, the flow sensor comprises: a housing which is installed on the fluid path and inside which a through hole is formed; a magnetic portion which is installed in a predetermined space along a circumferential direction of the through hole; and an impeller which is installed rotatively in the through hole wherein when a rotation velocity of the impeller is varied according to the flow passing through the fluid path, the magnetic portion detects the rotation velocity to transmit it to the controller. 
     The actuator comprises: a driving main body which is connected electrically to the controller and converts the electric signal from the controller (into kinetic force; and a moving rod which is extended from the driving main body to be inserted into the body and moves toward the sheet to adjust an opening amount of the sheet. 
     The driving main body comprises: a driving motor which is connected electrically to the controller to produce a driving force; a driving gear which transmits the driving force produced from the driving motor to the moving rod; and a variable resistor which is link-moved with the driving gear to sense a displacement amount of the moving rod and feedbacks the sensed displacement amount to the controller. 
     The variable flow valve according to a fourth embodiment comprises: a body inside which a fluid path through which the entrance and the exit are communicated is provided; a chamber which is partitioned inside the body by the upper and lower support rods and is communicated with the entrance and the exit of the body; a diaphragm one end of which is fixed to the lower support rod of the chamber and the other end of which is fixed to a slider connected to the resilient member provided inside the chamber, and which partitions the chamber into a first hydraulic pressure chamber to be communicated with the entrance of the body and a second hydraulic pressure chamber to be communicated with the exit of the body; and an actuator which is installed movably along the upper support rod of the chamber and adjusts a sectional area passing from the entrance of the body toward the chamber by a control signal from the controller. 
     Here, the resilient member is fitted between a guide protrusion to which the slider is mounted movably and the moving rod and is elastically biased by the slider when the diaphragm is deformed by a pressure difference between the first hydraulic pressure chamber and the second hydraulic pressure chamber. 
     At this time, the actuator comprises: a driving main body which is connected electrically to the controller and converts an electric signal from the controller into a kinetic force; a moving rod which is moved reciprocally on the driving main body and a lower end of which a plurality of screw threads are formed; and a flow blocking body which is connected to the screw thread of the moving rod and is moved vertically along the upper support rod when the moving rod is rotated, thereby to adjust a sectional area passing from the entrance of the body toward the chamber. 
     The actuator according another embodiment comprises: a driving main body which is connected electrically to the controller and converts an electric signal from the controller into a kinetic force; a moving rod which is installed rotatively on the driving main body and a lower end of which a plurality of screw threads are formed; and a flow blocking body which is connected to the screw thread of the moving rod and is moved vertically along the upper support rod when the moving rod is moved reciprocally, thereby to adjust a sectional area passing from the entrance of the body toward the chamber. 
     Here, the driving main body comprises: a driving motor which is connected electrically to the controller to produce a driving force; a driving gear which transmits the driving force produced from the driving motor to the moving rod; and a variable resistor which is link-moved with the driving gear to sense a displacement amount of the moving rod and feedbacks the sensed displacement amount to the controller. 
     Advantageous Effects 
     As set forth above, according to the present invention, when there occurs a heating-stop room, a total constant flow is controlled automatically to reduce by as much as the flow corresponding to the room and thus over-flow more than a setting amount toward other rooms which are being heated can be avoided, thereby to save heating cost and eliminate noise due to caviation. 
     Further, when a total constant flow is automatically reduced, corresponding to the heating-stop room, flow meeting the necessary request heating amount of the corresponding room is reduced, thereby to always maintain an optimum heating state. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other aspects, features and advantages of certain exemplary embodiments of the present invention will be more apparent from the following description taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a block diagram showing a warm water distribution device used in a prior differential pressure flow adjusting valve; 
         FIG. 2  is a view showing a control logic and its configuration according to a preferred embodiment of the present invention; 
         FIG. 3  is a cross-sectional view showing a variable flow valve according to a first embodiment of the present invention; 
         FIG. 4  is a cross-sectional view showing a variable flow valve according to a second embodiment of the present invention; 
         FIG. 5  is a cross-sectional view showing a variable flow valve according to a third embodiment of the present invention; 
         FIG. 6  is a front view showing a flow sensor used in the variable flow valve used in the third embodiment of the present invention; 
         FIGS. 7 and 8  are cross-sectional views showing the variable flow valve used in a fourth embodiment of the present invention; 
         FIG. 9  is a cross-sectional view showing a driving main body used in the present invention; 
         FIGS. 10-12  are experimental tables of the results which is obtained by comparing the apparatus according to the present invention and a prior differential pressure flow valve with respect to 4 rooms having different fluid amount from each other and which shows reduction differences of a total constant flow of a household, corresponding to the heating-stop room; 
         FIG. 13  is a table showing parameters of a house in which the device of the present invention is installed; and 
         FIGS. 14-16  are tables showing heat amount control results according to the prior art, comparing with the present invention. 
     
    
    
     BEST MODE 
     Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Wherever possible, the same reference numerals will be used to refer to the same elements throughout the specification, and a duplicated description thereof will be omitted. It will be understood that although the terms “first,” “second”, etc. are used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. 
     MODE FOR INVENTION 
     There are provided several rooms having different sizes (first room, second room, third room . . . nth room) in each household, as show in  FIG. 2 , wherein assuming for convenience that the first room is largest and room size gradually decrease toward nth room, it is generally inferred that a necessary request heating amount for heating each room is in proportion to a room floor area. 
     However, the inference that the necessary request heating amount is in proportion to a room floor area is not reasonable theory which neglects a heating load and in case where the heating load is considered while actually designing a heating system, the necessary request heating amount may be varied even in case of the same room floor area, and further the necessary request heating amount of a room having a smaller floor area may be greater than that of a room having a larger floor area. 
     Accordingly, the heating system may be designed by considering the respective room area and various heat loss caused from a window number and size, a room location according to the design criteria, and calculating the heating load per room and determining the necessary request heating amount depending on the heating load. 
     The formula for calculating the heating load per room is as followings. 
         L =Σ( K×A×N×Δt )  (1)
 
     Here,
         L=heating load   K=heat transmission rate [kcal/hk]   A=area   N=azimuth coefficient   Δt=relevant temperature difference       

     That is, the heating load per room is calculated by summating all “face heating load” of the respective face forming the room wherein the face heating load is obtained by multiplying one more factors selected among the heat transmission rate, the area, the azimuth coefficient, and the relevant temperature difference. Herein, the formula 1 is an ideal exemplary formula for obtaining the best precise heating load wherein 4 factors (the heat transmission rate, the area, the azimuth coefficient, and the relevant temperature difference) are all selected. 
     In the formula 1, the heat transmission rate value as one factor for calculating the heating load is associated with material self property forming the room wherein the large heat transmission rate means a large heat loss. For example, the heat transmission rate of a glass window is 4.73 which is greater than 1.38 of a wood window, and thus the heat loss of the glass window is larger than that of the wood window. 
     Generally, the heat transmission rate is selected depending on the material forming a room, bases on  ┌ heat transmission rate table of a part of a building per region ┘  made under a installment standard decree  21 . 
     Further, the area value among the factors does not mean a floor area of the corresponding room but all surface areas surrounding the corresponding rooms, and generally a room is a hexahedral shape and thus the area value determined by considering area values of 4 wall faces, a ceiling and a floor. 
     In addition, the azimuth coefficient among the factors is determined by considering the heat loss difference depending on azimuths of east, west, north and south. 
     Furthermore, the relevant temperature difference means a temperature difference between an inner face and an outer face based on a one face forming a room (for example, wall face) wherein in case of a outer wall, the heat loss is to be large and as a result the corresponding temperature is to be large. 
     The best precise heating load is obtained, as indicated in the formula 1, by summating all, “face heating load (heat transmission rate×area×azimuth coefficient×relevant temperature difference)” of each face forming a room, as set forth above, and when one wall face is formed with different materials, the heat transmission rate, area, azimuth coefficient and relevant temperature difference are obtained respectively for the different materials and then summated as the heat transmission rate, area, azimuth coefficient and relevant temperature difference for the wall face. 
     For example, if a wall face is formed with concrete and a glass window, the heating load of the wall face is obtained by summating a value that the face area excluding the glass window is multiplied by the heat transmission rate, area, azimuth coefficient and relevant temperature difference of a concrete, and a value that a glass window area is multiplied by the heat transmission rate, area, azimuth coefficient and relevant temperature difference of a glass. 
     Further, for obtaining the wall face heating load the four factors all do not need to be multiplied, if necessary, the selected factors only are to be multiplied. For example, when one wall face is an outer wall, the azimuth coefficient among the factors has to be considered; however, when the wall face is an inner wall, the azimuth coefficient may be excluded to calculate the heating load. 
     Accordingly, even though a precision degree of the wall face heating load decreases a little bit, only the area has to be considered, only “area×heat transmission rate” has to be considered and at least one of the azimuth coefficient and the relevant temperature difference are additionally considered thereto. 
     When the heating load is calculated for a room, a necessary request heating amount necessary for optimally heating the room is obtained base on the heating load by using a below formula. 
         Q=G×C×ΔT   (formula 2)
 
     Here,
         Q=necessary request heating amount[kcal/h]   G=flow[lph]   C=specific heat[kcal/kg° C.]   ΔT=temperature variation (indoor supply temperature−indoor water returning temperature)       

     Herein, the specific heat is a constant value (that is, warm water is used and thus the specific heat is 1), the temperature variation value is a constant value since the temperature variation has to be always kept as 15° C. for meeting the design criteria as set forth in the prior art. 
     Eventually, the necessary request heating amount is in proportion to the flow and thus in order to increase the necessary request heating amount the flow has to be increased wherein when the necessary request heating amount per room is decided, an optimum flow for meeting the necessary request heating amount per room is to be set to calculate the optimum flow per room can be calculated. 
     The calculated optimum flow value per room is stored to a controller, which will be later described, and used when controlling a flow of a variable flow valve  200 - 500 , which will be later described. 
     Hereinafter, a basic configuration of an apparatus for automatically controlling a constant flow according to a preferred embodiment of the present invention will be described. 
     As shown in  FIG. 2 , the apparatus for automatically controlling a constant flow mainly includes a supply tube  2 , a warm water duct  4 , a water returning pipe  5 , a water returning tube  7 , a temperature adjusting unit  110 , a driver  120 , a variable flow valve  200 - 500  and a controller  130 . 
     The supply tube  2  is configured for supplying warm water to each household and the warm water duct  4  is communicated with the supply tube  2  and is branched into the respective room where warm water latent heat is exchanged to the corresponding room. 
     The warm water duct  4  may be directly communicated with the supply tube  2 , and generally the supply tube  2  is connected to a warm water supply header  3  and the warm water duct  4  is branched from the warm water supply header  3  into the respective room for respectively heating each room through flowing warm water. 
     The warm water which has finished heat-exchanging with the respective room is returned through a water returning pipe  5  communicated with the respective warm water duct  4 , and the returned warm water is collected again to the warm water returning header  6  and then flows of the water returning pipes  5  are collected on one place through the water returning tube connected to the warm water returning header  6  and are returned to an external central water returning tube (not shown). 
     According to the present invention, an apparatus for automatically controlling a constant flow is provided to save a heating cost by reducing a total constant flow by as much as corresponding to the flow of actually heating-stop room (already calculated optimum flow) when one or more rooms in a household having the heating system as set forth above are stopped heating, and interrupt noise creation due to cavitation by avoiding more amount of flow than the optimum flow originally set from being flowed into other rooms which are being heated to prevent a flow velocity increase of the water returning pipe which is heating. 
     Herein, the temperature adjusting unit  110  may be provided on the respective room to separately set a desired temperature for the respective room, though which the desired temperature may be set by a user and further indoor temperature of the respective room may be measured. 
     Furthermore, an air temperature sensor may be embedded in the temperature adjusting unit  110  and a desired temperature by a user is to be set by rotating a button or an adjusting knob wherein the temperature adjusting unit  110  has been known and thus detailed description thereof is omitted. 
     The driver  120  may be provided on the water returning pipe  5  of the respective room to respectively open and close the water returning pipes  5  depending on electric signals of the controller  130 , which will be described later wherein when the driver  120  opens the water returning pipe  5 , warm water can flow through the corresponding room to heat the room, and when the driver closes the water returning pipe  5 , warm water cannot flow through the corresponding room to stop the heating. 
     The driver  120  may be operated by external electric signals wherein a valve inside the water returning pipe  5  is operated by receiving the electric signals to open and close a passage of the water returning pipe  5 . 
     In addition, the variable flow valve  200 - 500  may be provided in the supply tube  2  or the water returning tube  7  to vary the flow of the supply tube  2  or the water returning tube  7  depending on other electric signals from the controller  130 , in which a total constant flow is restricted. 
     When an electric signal is applied to the variable flow valve  200 - 500 , a flow passage sectional area of the supply tube  2  or the water returning tube  7  (hereinafter, assuming that the variable flow valve  200 - 500  is provided in the water returning tube  7  for convenience, as shown in drawings) is adjusted to vary flow passing through the water returning tube  7 , the configuration of the variable flow valve  200 - 500  is described in detail according to the embodiments in  FIG. 3  (embodiment 1),  FIG. 4  (embodiment 2),  FIG. 5  (embodiment 3), and  FIGS. 7 and 8  (embodiment 4). 
     First, as shown in  FIG. 3 , the variable flow valve  200  according to the first embodiment mainly includes a body  210 , a chamber  220 , a diaphragm  230 , a moving body  240  and an actuator  250 . 
     Here, an entrance  211  through which returning fluid is input is formed on inner one side of the body  210  and an exit  212  through which the returning fluid is discharged is formed on the other side thereof wherein a fluid path through which the entrance  211  and the exit  212  are communicated is provided on inner side of the body  210 . 
     Further, sheets  213  are formed between the entrance  211  and the exit  212  of the body  210 , which decreases a sectional area of the fluid path, and the fluid entered into the body  210  through the entrance  211  passes through the sheet  213  and discharges outside through the exit  212 . 
     The chamber  220  is a predetermined space formed on one inner side of the body  210  wherein hydraulic pressure passages  221 ,  222  are formed on the chamber  220  to apply hydraulic pressures toward an entrance  211  side and a sheet  213  side, respectively. 
     Referring to  FIG. 3 , a first hydraulic pressure passage  221  to be communicated with an entrance  211  side is formed in the chamber  220  to apply hydraulic pressure toward an entrance  211  side and further a second hydraulic pressure passage  222  to be communicated with a sheet  213  side is formed in the chamber to apply hydraulic pressure toward a sheet  213  side. 
     Accordingly, a first hydraulic pressure chamber  223  to be communicated with the first hydraulic pressure passage  221  and a second hydraulic pressure chamber  224  to be communicated with the second hydraulic pressure passage  222 , which are partitioned by a diaphragm  230 , are provided on the chamber  220 . 
     The diaphragm  230  is provided to partition the chamber  220  into the first hydraulic pressure chamber  223  and the second hydraulic pressure chamber  224 , which is deformed by a pressure difference when hydraulic pressure applies to both sides of the diaphragm  230  toward an entrance  211  side and a sheet  213  side, respectively. 
     The moving body  240  is connected to one side of the diaphragm  230  and installed elastically to adjust a sectional area passing from the sheet  213  toward the exit  212  due to a pressure difference in the chamber  220  wherein when the diaphragm  230  is deformed due to the pressure difference of the chamber  220 , the moving body  240  approaches toward the sheet  213  due to a deformation force of the diaphragm  230 . 
     Herein, the moving body  240  includes a head portion  241 , a stem portion  242  and a resilient member  243  wherein the head portion  241  is connected to the diaphragm  230 . 
     Further, the stem portion  242  is extended from the head portion  241  toward the sheet  213  to adjust the flow sectional area passing from the sheet  213  toward the exit  212  due to a deformation of the diaphragm  230 . 
     Accordingly, when the stem portion  242  is moved due to the deformation of the diaphragm  230  to increase or decrease the sectional area passing from the sheet  213  toward the exit  212  and thereby to lower or raise hydraulic pressure on the sheet side. 
     Furthermore, the second hydraulic pressure passage  222  to be communicated with the second hydraulic pressure chamber  224  may be formed on the body  210  to communicate with a sheet  213  side; however, in the present invention, the second hydraulic pressure passage  222  is formed inside the stem portion  242 . 
     Accordingly, the second hydraulic pressure chamber  224  is communicated with a sheet  213  side through the second hydraulic pressure  222  formed inside the stem portion  242 . 
     Further, the moving body  240  is to be returned to an initial location, as shown in  FIG. 3 , while the first hydraulic pressure chamber  223  and the second hydraulic pressure chamber  224  are at same pressure wherein the resilient member  243  is provided between the moving body  240  and the chamber  220 . 
     While a fluid of a predetermined hydraulic pressure is flowing into the body  210 , in case where a fluid of higher hydraulic pressure flows at a predetermined moment into the chamber, the hydraulic pressure at an entrance  211  side becomes higher than that of the sheet  213  and thus a pressure of the first hydraulic pressure chamber  223  to be communicated with the entrance  211  becomes higher than that of the second hydraulic pressure chamber  224  to be communicated with the sheet  213 . As a result, the pressure of the first hydraulic pressure  223  applies to a side of the second hydraulic pressure chamber  224  due to the pressure difference to deform the diaphragm  230  to be bent toward the second hydraulic pressure chamber  224  and the moving body  240  is to be pushed toward the sheet  213  due to this deformation of the diaphragm  230  so that a distal end of the moving body  240  reduces a sectional area passing from the sheet  213  toward the exit  212 . 
     When the sectional area passing from the sheet  213  toward the exit  212  is reduced, the hydraulic pressure of the sheet  213  gradually increases to be eventually equal to an hydraulic pressure at an entrance  211  side, and when the hydraulic pressures of an entrance  211  side and a sheet  213  side are equal, the pressure of the first hydraulic pressure chamber  223  and the second hydraulic pressure chamber  224  becomes an equilibrium state so that the moving body  240  is returned to an original location due to its resilient force. 
     Likewise, the chamber  220 , the diaphragm  230  and the moving body  240  are configured for the hydraulic pressure at the sides of the entrance  211  and the sheet  213  to be always equal. Here, the reason for maintaining the pressures to be equal is that a sectional area of a flow passing from the entrance  211  toward the sheet  213  is adjusted to control precisely the flow as a desired flow through the equal pressure at the sides of the entrance  211  and the sheet  213 . 
     Meanwhile, while maintaining the equal hydraulic pressure at the sides of the entrance  211  and the sheet  213  through the configuration as set forth above, a flow passing through the sheet is controlled by an actuator  250 . 
     The actuator  250  may be provided on the other side of the body  250  and through which a sectional area passing from the entrance  211  toward the sheet  213  is adjusted due to an electrical signal to control actually the flow wherein the actuator is common element to be used in other embodiments. Herein, the other embodiments are to be described and then the actuator will be described later. 
     Meanwhile, as shown in  FIG. 4 , a variable flow valve  300  according to the second embodiment mainly includes a body  310 , a chamber  320 , a diaphragm  330 , a moving body  340  and an actuator  350 . 
     Here, an entrance  311  through which returning fluid is input is formed on inner one side of the body  310  and an exit  312  through which the returning fluid is discharged is formed on the other side thereof wherein a fluid path through which the entrance  311  and the exit  312  are communicated is provided on inner side of the body  310 . 
     Further, sheets  313  are formed between the entrance  311  and the exit  312  of the body  310 , which decreases a sectional area of the fluid path, and the fluid entered into the body  310  through the entrance  311  has to pass through the sheet  313  and discharge outside through the exit  312 . 
     The chamber  320  is a predetermined space formed between the entrance  311  and the exit  312  among inner part of the body  310  and in the present embodiment the chamber  320  is formed adjacently to the sheet  313  wherein hydraulic pressure passages  321 ,  322  are formed on the chamber  320  to apply hydraulic pressures toward an entrance  311  side and a sheet  313  side, respectively. 
     Referring to  FIG. 4 , a first hydraulic pressure passage  321  to be communicated with a sheet  313  side is formed in the chamber  320  to apply hydraulic pressure toward a sheet side  313  and further a second hydraulic pressure passage  322  to be communicated with an exit  312  side is formed in the chamber to apply hydraulic pressure toward an exit  312  side. 
     Accordingly, a first hydraulic pressure chamber  323  to be communicated with the first hydraulic pressure passage  321  and a second hydraulic pressure chamber  324  to be communicated with the second hydraulic pressure passage  322 , which are partitioned by a diaphragm  330 , are provided on the chamber  320 . 
     The diaphragm  330  is provided to partition the chamber  320  into the first hydraulic pressure chamber  323  and the second hydraulic pressure chamber  324 , which is deformed by a pressure difference when hydraulic pressure applies to both sides of the diaphragm  330  toward a sheet  313  side and an exit  312  side, respectively. 
     Herein, an outer peripheral surface of the diaphragm  330  is fixed to an inner wall of the chamber  320  to be installed in the chamber  320  and a through portion  331  to which a moving body  340 , which will be described later, is connected is formed on inner peripheral surface of the diaphragm. 
     The moving body  340  is connected to the diaphragm  330  and installed elastically to adjust a sectional area of a direction change place (hereinafter, referred to as “inflection portion”) among places passing from the entrance  311  toward the sheet  313  due to a pressure difference in the chamber  320  wherein when a pressure at a sheet  313  side is greater than that of an exit  312  side, the moving body  340  is moved by receiving a deformation force from the diaphragm  330  to reduce a sectional area of the inflection portion  314 . 
     Herein, the moving body  340  includes a head portion  341 , a stem portion  342  and a resilient member  343  wherein the head portion  341  is fitted into the through portion  331  of the diaphragm  330 . 
     Further, the stem portion  342  is extended from the head portion  341  toward the inflection portion  314  where an entrance  311  side and a sheet  313  side are communicated to adjust the sectional area of the inflection portion  314  passing from the entrance  311  toward the sheet  313  due to a deformation of the diaphragm  330 . 
     Accordingly, when the stem portion  342  is moved due to the deformation of the diaphragm  330 , the flow sectional area of the inflection portion  314  is increased or decreased to adjust the flow of the inflection portion  314  depending on a pressure variation and thereby maintain a constant hydraulic pressure at a sheet  313  side. 
     Further, when the first hydraulic chamber  323  and the second hydraulic chamber  324  are in a same pressure state, the moving body  340  is to be returned to an initial location wherein the resilient member  343  is installed resiliently on the moving body  340  for the moving body  340  to be returned when pressures of both sides are equal based on the diaphragm  330 . 
     Furthermore, an adjusting screw  315  for adjusting initially pass flow passing through the inflection portion  314  by adjusting an interval from the stem portion  342  may be provided on the inflection portion  314 . 
     The adjusting screw  315  is provided to be manually handled when an initial flow is set and once it is handled, it cannot be changed until manually handling the adjusting screw. 
     In summary, while a fluid of a predetermined hydraulic pressure is flowing into the body  310 , in case where a fluid of higher hydraulic pressure flows at a predetermined moment into the chamber, the hydraulic pressure at a side of the sheet  313  becomes higher than that of an exit  312  side and thus a pressure of the first hydraulic pressure chamber  323  to be communicated with a sheet  313  side becomes higher than that of the second hydraulic pressure chamber  324  to be communicated with an exit  312  side. As a result, the pressure of the first hydraulic pressure  323  applies toward the second hydraulic pressure chamber  324  due to the pressure difference to deform the diaphragm  330  to be bent toward the second hydraulic pressure chamber  324  and the moving body  340  is moved toward the inflection portion  314  due to this deformation of the diaphragm  330  so that a distal end of the stem portion  342  reduces a flow sectional area of the inflection portion  314  passing from the entrance  311  toward the sheet  313 . 
     When the flow sectional area of the inflection portion  314  is reduced, the hydraulic pressure of the sheet  313  gradually decreases to be eventually equal to an hydraulic pressure at an exit  312  side, and when the hydraulic pressures of a sheet  313  side and an exit  312  side are equal, the pressure of the first hydraulic pressure chamber  323  and the second hydraulic pressure chamber  324  becomes an equilibrium state so that the moving body  340  is returned to an original location due to its resilient force. 
     Likewise, the chamber  320 , the diaphragm  330  and the moving body  340  are configured for the hydraulic pressures of the sides of the sheet  313  and the exit  312  to be always equal. Here, the reason for maintaining the pressures to be equal is that a sectional area of a flow passing through the sheet  313  is adjusted to control precisely the flow as a desired flow through the equal pressure of the sides of the sheet  313  and the exit  312 . If the pressure becomes different, a flow passing through the sheet  313  is varied. 
     Meanwhile, while maintaining the equal hydraulic pressure at front and rear sides of the sheet  313  through the configuration as set forth above, a flow passing through the sheet is adjusted by the actuator  350  wherein a total flow passing through the water returning tube  7  is eventually adjusted precisely by the actuator  350 . 
     The actuator  350  may be provided on the other side of the body  350  and through which a opening amount of the sheet  313  is adjusted to control actually the flow depending on an electrical signal wherein the actuator  313  adjusts actually a sectional area of the flow passing through the sheet  313  to control the flow. The actuator will be described in detail later. 
     Meanwhile, as shown in  FIG. 5 , a variable flow valve  400  according to the third embodiment mainly includes a body  410 , a flow sensor  430  and actuator  450 . 
     Here, an entrance  411  through which returning fluid is input is formed on inner one side of the body  410  and an exit  412  through which the returning fluid is discharged is formed on the other side thereof wherein a fluid path through which the entrance  411  and the exit  412  are communicated is provided on inner side of the body  410 . 
     Further, sheets  413  are formed between the entrance  411  and the exit  412  of the body  410 , which decreases a sectional area of the fluid path, and the fluid entered into the body  410  through the entrance  411  passes through the sheet  413  and discharges outside through the exit  412 . 
     The flow sensor  430  is provided on the fluid path of the body  410  to directly measure a flow of a fluid passing through the fluid path and in the present embodiment the flow sensor  430  is provided on a side of the exit  412  to measure the flow of the fluid having passed through the sheet  413 ; however, an arrangement of the flow sensor  430  is not limited thereto, and the flow sensor  430  may be provided on a side of the entrance  411 . 
     The pressure of a fluid on inner fluid path of the body  410  connected to the water returning tube  7  is ever-changed and even though an unit for making the front and rear pressures of the sheet  423  to be equal has been conventionally used to control a constant flow through the actuator  450 , which will be described later, under a circumference of pressure continuously being changed, and in the third embodiment of the present invention the flow inside the fluid path is directly measured to adjust in real time a sectional area of the flow depending on the flow variation to control the flow. 
     Accordingly, when a passing flow on the fluid path which is measured through the flow sensor  430  is great, a flow sectional area of the sheet  413  has to be decreased and when the passing flow is small, the flow sectional area of the sheet  413  has to be increased thereby for a constant flow to be flowed, regardless of flow variation. 
     As shown in  FIG. 6 , the flow sensor  430  may include a housing  431 , a magnetic portion  432 , and an impeller  433  wherein the housing  431  is provided on a fluid path of the body  410 , and may be formed with high corrosion-proof material not to be corroded with fluid and further a through hole  431   a  through which a fluid passes is formed inside the housing  431 . 
     Accordingly, when the housing  431  is provided on the fluid path in a direction of crossing to a flow direction of a fluid, all fluid flowing the fluid path has to pass through the through hole  431   a.    
     The magnetic portion  432  is provided in inner circumferential direction of the through hole  431   a  and may be provided as a single; however, in the present embodiment of the present invention a plurality of the magnetic portions are provided at a predetermined space along an inner circumferential direction of the through hole  431   a  in order to prepare for failure or increase a precision degree of the sensor wherein the number of the magnetic portion may be selected depending on necessity of a user. 
     The impeller  433  is provided rotatively on the through hole  431   a  wherein the impeller  433  is rotated by receiving a collision energy from a fluid flowing through the fluid path, and the whole impeller  433  is made of metal material or a metal part is provided on a distal end of the impeller  433  so that when the impeller  433  is rotated, the magnetic portion  432  detects rotation number of the impeller  433 . 
     Accordingly, when a vane (blade) of the impeller  433  passes near the magnetic portion  432  during a rotation of the impeller  433 , a magnetic flux density of the magnetic portion  432  is varied and thus a voltage is produced on a coil inside the magnetic portion  432  wherein the voltage is input into a controller  130  as a pulse form when several vanes (blades) passes near the magnetic portion  432  due to a rotation of the impeller  433 . At this time, the controller  130  receives the pulse signal to detect a rotation velocity of the impeller  433 . 
     As the flow passing through the fluid path becomes greater, the collision energy to be transmitted to the impeller  433  further increases to accelerate the rotation velocity of the impeller  433  and thus the flow passing through the fluid path can be directly measured through the rotation velocity of the impeller  433 . 
     Further, as shown in  FIG. 5 , the actuator  450  is provided to adjust an opening amount of the sheet  413  wherein the flow passing by the sheet  413  is adjusted by the actuator  450  and when the flow passing by the sheet  413  is adjusted, a total flow passing through the water returning tube  7  is eventually adjusted. 
     The actuator  450  is provided on one side of the body  410  to adjust the opening amount of the sheet  413  depending on electric signals. 
     Accordingly, the flow sensor  430  directly measures a flow passing inside the fluid path and sends the measured information to the controller  130 , and then the controller  130  controls the actuator  450  by the information from the flow sensor  430  to adjust a flow sectional area in the sheet  413 , thereby allowing a constant flow to be always flowed. 
     The actuators  250 ,  350 ,  450  used in the first, second and third embodiments of the present invention mainly includes a driving main body  251 ,  351 ,  451  and a moving rod  252 ,  352 ,  452  wherein the driving main body  251 ,  351 ,  451  is connected electrically to the controller  130 , which will be described later, and receives electric signals from the controller  130  and converts them into kinetic force. 
     The kinetic force of the driving main body  251 ,  351 ,  451  is transmitted to the moving rod  252 ,  352 ,  452  and an opening amount of the sheet  213 ,  313 ,  413  is adjusted by length variation due to a movement of the moving rod  252 ,  352 ,  452 . The driving main body will be described later. 
     Meanwhile, as shown in  FIGS. 7 and 8 , a variable flow valve  500  according to the fourth embodiment mainly includes a body  510 , a chamber  520 , a diaphragm  530  and an actuator  550 . 
     Herein, an entrance  511  through which returning fluid is input is formed on inner one side of the body  510  and an exit  512  through which the returning fluid is discharged is formed on the other side thereof wherein a fluid path through which the entrance  511  and the exit  512  are communicated is provided inside the body  510 . 
     The chamber  520  is a predetermined space formed on one inner side of the body  510  wherein the chamber is partitioned by an upper and lower cylindrical support rods  521 ,  522  provided inside the body  510  and is communicated with the entrance  511  and the exit  522  of the body. The upper and lower support rods  521 ,  522  are cylindrical elements and may be provided inside the body  510 , or extended from the body as a part of the body. 
     The chamber  520  is partitioned by a diaphragm  530  installed on a lower part of the body  510  into a first hydraulic pressure chamber  524  and a second hydraulic pressure chamber  525  wherein a hydraulic pressure at a side of the entrance  511  applies to the first hydraulic pressure chamber  524  through a hydraulic pressure path  523  connected to the entrance  511  of the body  510  and an hydraulic pressure in the second hydraulic pressure chamber  525  is varied with increasing and decreasing of a sectional area passing toward the exit  512  by a deformation of the diaphragm  530 . 
     One end of the diaphragm  530  is fixed to the lower support rod  522  of the chamber  520  and the other end thereof is fixed to a slider  540  connected to a resilient member  543  which is installed within the chamber  520 . As a result, the chamber  520  is partitioned into the first hydraulic pressure chamber  524  to be communicated with the entrance  511  of the body  510  and the second hydraulic pressure chamber  525  to be communicated with the exit  512  of the body  510 . 
     In more detailed description of installing the diaphragm  530 , one end of the diaphragm  530  is installed on the lower support rod  522  of the chamber  520  and fixed thereto not to be moved even in case of hydraulic pressure of the first hydraulic pressure chamber  524  and the second hydraulic pressure chamber  525  being varied. Meanwhile, the other end of the diaphragm  530  is fixed to the slider  540  and the slider  540  is fitted into a guide protrusion  513  protruded from a floor of the chamber  520  and moved vertically due to hydraulic pressure variation of the first hydraulic pressure chamber  524  and the second hydraulic pressure chamber  525 . 
     A resilient member  545  such as coil spring is fitted between the guide protrusion  513  and a moving rod  522 , which will be described later. Here, fitting stumbles  514 ,  554  are formed on the upper end of the guide protrusion  513  and a lower end of the moving rod  552 , respectively, to prevent the resilient member  545  being separated. 
     The resilient member  545  is installed to be elastically biased when the slider  540  is moved along the guide protrusion  513  due to the hydraulic pressure variation of the first hydraulic pressure chamber  524  and the second hydraulic pressure chamber  525 . When the first hydraulic pressure chamber  524  and the second hydraulic pressure chamber  525  are under a same pressure, the resilient member  545  allows the slider  540  to be returned to an initial location, as indicated by a solid line in  FIG. 7 . 
     While a fluid of a predetermined hydraulic pressure is flowing into the body  510 , in case where a fluid of higher hydraulic pressure flows at a predetermined moment into the body, the hydraulic pressure at a side of the entrance  511  becomes higher than that of the exit  512  and thus a pressure P 1  of the first hydraulic pressure chamber  524  to be communicated with the entrance  511  becomes higher than the pressure P 2  of the second hydraulic pressure chamber  525  to be communicated with the exit  512 . Due to this pressure difference, the pressure of the first hydraulic pressure chamber  524  applies toward the second hydraulic pressure chamber  525  and, as indicated with a dotted line in  FIG. 7 , thus the slider  540  connected to the diaphragm  530  rises toward the second hydraulic pressure chamber  525  and at the same time the diaphragm  530  itself is deformed to swell toward the second hydraulic pressure chamber  525 . As a result, a sectional area d 2  of a path in communication between the second hydraulic chamber  525  and the exit  512  is reduced. 
     When the sectional area d 2  passing from the second hydraulic pressure chamber  525  toward the exit  512  is reduced, the hydraulic pressure of the second hydraulic pressure chamber  525  increases gradually to eventually be equal to the hydraulic pressure of the first hydraulic pressure chamber  524 , and when the pressure of the first hydraulic pressure chamber  524  and the second hydraulic pressure chamber  525  are in equilibrium state (p 1 =p 2 ), the slider  524  is returned to an initial location by the resilient member  545 . 
     Likewise, the chamber  520 , the diaphragm  530  and the slider  540  are configured for the hydraulic pressure at the sides of the entrance  511  and the exit  512  to be always equal. Here, the reason for maintaining the pressures to be equal is that a sectional area of a flow passing from the entrance  511  toward the exit  512  is adjusted to control precisely the flow as a desired flow through the equal pressure at the sides of the entrance  511  and the exit  512 . 
     Meanwhile, while maintaining the equal hydraulic pressure at the sides of the entrance  511  and the exit  512  through the configuration as set forth above, a flow passing through the chamber  520  is controlled by an actuator  550 . 
     The actuator  550  may be provided on upper part of the body  510  to actually adjust a flow by adjusting a sectional area passing from the entrance  511  toward the chamber  520  according to an electrical signal wherein the actuator  550  actually controls the flow by actually adjusting a sectional area d 1  passing from the entrance  511  of the body  510  toward the chamber  520 . 
     The actuator  550  mainly includes a driving main body  551 , a moving rod  552  and a flow blocking body  555  wherein the driving main body  551  is connected electrically to a controller  130 , which will be described later, and receives an electric signal from the controller  130  and converts it into a kinetic force. The driving main body  551  will be described later. 
     The moving rod  552  and the flow blocking body  555  in the actuator  550  are operated in two kinds of way, each of which will be described simply, referring to  FIGS. 7 and 8 . 
     As shown in  FIG. 7 , the actuator includes the moving rod ( 552 ) which is provided rotatively to the driving main body  551  and on a lower end of which a plurality of screw threads  553  are formed, and the flow blocking body  555  which is connected to the screw thread  553  of the moving rod  552  and is moved vertically along the upper support rod  521  of the chamber  520  when the moving rod  552  is rotated, and adjusts the sectional area d 1  passing from the entrance  511  toward the chamber  520 . 
     According to this configuration, the moving rod  552  is only rotated to both directions at its place and the flow blocking body  555  moves vertically along the screw thread of the moving rod  552  to adjust the sectional area. At this time, since the moving rod  552  is not moved vertically, the resilient member  545  fitted into a lower end of the moving rod is not biased. 
     Further, as shown in  FIG. 8 , the actuator includes the moving rod  552  which is provided reciprocally movable to the driving main body  551  and on a lower end of which a plurality of screw threads  553  are formed, and the flow blocking body  555  which is connected to the screw thread  553  of the moving rod  552  and is moved vertically along the upper support rod  521  of the chamber  520  when the moving rod  552  is reciprocated straightly, and adjusts the sectional area d 1  passing from the entrance  511  of the body  510  toward the chamber  520 . 
     According to this configuration, as the moving rod is reciprocated vertically and straightly, the resilient member  545  fitted into a lower end thereof is elastically biased to vary uniformly and smoothly a sectional area. 
     The driving main body  251 ,  351 ,  451 ,  551  used in the first to fourth embodiment of the present invention is configured as shown in  FIG. 9  wherein the controller  130  is connected electrically to a driving motor  253  of the driving main body  251 ,  351 ,  451 ,  551  to operate the driving motor  253  wherein the driving motor  253  applies a rotation force to a driving gear  255  through a reduction gear  254 . 
     The driving gear  255 , which is not shown in  FIG. 9 , is connected to the moving rod  252 ,  352 ,  452 ,  552  such that the driving gear transmits power to the moving rod and provides external force for allowing the moving rod  252 ,  352 ,  452 ,  552  to be moved straightly. 
     At this time, since the controller senses the flow passing through the sheet  213 ,  313 ,  413 ,  513 , on the condition that the controller receives location information of the straightly moved moving rod  252 ,  352 ,  452 ,  552 , the driving gear  255  is connected to the sensor gear  257  through the connection gear  256 . 
     Accordingly, when the driving gear  255  is rotated, the sensor gear  257  is linked-rotated wherein a known variable resistor  258  is embedded in the sensor gear  257  and out value from the variable resistor  258  is input to the controller  130 , and thus the controller  130  receives in real time the output value from the variable resistor  258  and detects a rotation amount of the driving gear  255 , that is, the location of the moving rod  252 ,  352 ,  452 ,  552 . 
     The driving gear  255  may be rotated at least one time and the rotation number of sensor gear  257  is limited to less than one time since the sensor gear  257  is in contact with the variable resistor  258  when rotating. Accordingly, a proper gear ratio between the driving gear  255  and the sensor gear  257  may be set in consideration of the rotation range. For reference, in the present invention, a rotation angle of the sensor gear  257  is limited to less than 270 degree and the variable resistor  258  is installed within the rotation angle range. Here, the flow is estimated by the controller  130  when a moving distance of the moving rod  252 ,  352 ,  452 ,  552  is informed since various parameters such as the moving distance of the moving rod  252 ,  352 ,  452 ,  552  and a diameter of the sheet  213  are input into the controller  130 . 
     Likewise, while the moving rod  252 ,  352 ,  452 ,  552  is extended from the driving main body  251 ,  351 ,  451 ,  551  to be inserted into the body  210 ,  310 ,  410 ,  510 , the moving rod  252 ,  352 ,  452 ,  552  receives force from the driving main body  251 ,  351 ,  451 ,  551  to adjust a sectional area entering toward the sheet  213 ,  313 ,  413 ,  513  wherein a flow is controlled as the moving rod  252 ,  352 ,  452 ,  552  adjusts a sectional area of the sheet  213 ,  313 ,  413 ,  513 . 
     At this time, an outer diameter of the moving rod  252 ,  352 ,  452 ,  552  may be corresponded to an inner diameter of the moving rod  252 ,  352 ,  452 ,  552  wherein when the moving rod  252 ,  352 ,  452 ,  552  is fitted completely into the sheet  213 ,  313 ,  413 ,  513 , the fluid cannot flow and thus passing flow becomes “0”. 
     Meanwhile, the controller  130  is configured in such a manner that, as shown in  FIG. 2 , the controller receives signal from the temperature adjusting portion  110  to control the driver  120  and the variable flow valve according to the signal. 
     Since a desired temperature by a user is to be set in the temperature adjusting portion  110  and current indoor temperature is measured by the temperature adjusting portion, as set forth above, the desired temperature being set to the temperature adjusting portion  110  and the current indoor temperature sensed by the temperature adjusting portion  110  are all input into the controller  130 . 
     The controller  130  compares the input desired temperature and the current temperature and in case where the current temperature is lower than the desired temperature, heating needs and thus an ON signal is given to the driver  120  to allow the corresponding water returning pipe  5  to be opened. 
     At this time, in case where the desired temperature becomes equal to the current temperature and it is request to stop heating, the controller  130  gives an OFF signal to the driver  120  of the corresponding room to close the water returning pipe  5  of the corresponding room. 
     At this time, the controller  130  allows that the flow of the variable flow valve  200 - 500  is reduced and a total constant flow per household passing through the variable flow valve  200 - 500  is equal to a summation of flow of each room being heated according to a proportion of an optimum flow value of closed rooms to an optimum flow value of a total rooms wherein the optimum flow value is stored in the controller, which is in proportion to a necessary request heat amount necessary for optimum heating the corresponding room in consideration of heating load in each room optimum, as set forth above. 
     The control signal sent from the controller  130  to the variable flow valve  200 - 500  is sent to the driving main body  251 ,  351 ,  451 ,  551  among the actuator  250 ,  350 ,  450 ,  550  of the variable flow valve  200 - 500  to adjust a moving distance of the moving rod  252 ,  352 ,  452 ,  552 . Here, the flow according to a moving distance of the moving rod  252 ,  352 ,  452 ,  552  is estimated by the controller  130  to which various parameters such as the moving distance of the moving rod  252 ,  352 ,  452 ,  552  and a diameter of the sheet  213 ,  313 ,  413 ,  513  are input. 
     If the heating is performed in only one room, the controller  130  opens only the water returning pipe  7  of a room being heated and closes the water returning pipe  7  of the other rooms (heating stopped rooms), and controls to allow the flow equal to the optimum flow value of the room being heated (the flow in consideration of heating load) to be flowed to the variable flow valve  200 - 500 . 
     Additional examples will be described below, referring to experimental data of  FIGS. 10-12   
       FIGS. 10-12  are experimental tables of the results which are obtained by comparing the apparatus according to the present invention and a prior difference pressure flow valve with respect to 4 rooms having different flow from each other and which shows reduction differences of a total constant flow of a household, corresponding to the heating-stopped room. Herein, an optimum value is an ideal value of a total constant flow of the corresponding household, which is calculated according to whether heating or non-heating each room. 
     Further, the driver opening means that the corresponding room is heated, and for example when the driver opening is “1+2+3+4”, the rooms  1 ,  2 ,  3 , and  4  are heating, and further when the driver opening is “1”, the room  1  is heating and the rest rooms  2 ,  3 , and  4  are stopped heating. 
     First, referring to  FIG. 10 , when the driver opening is in a state of “1+2+3+4”, the flows of the present invention and differential pressure valve all similar to the optimum value; however, when the driver opening is in a state of “1+2+4”, “1+2+3” and “1+3+4”, which means that one room is stopped being heated, the flow of the present invention approaches to the optimum value, the flow of the prior differential pressure valve is different from the optimum value, which shows that flow control has not performed properly. 
     This result means that in spite of one room not being heated properly the total constant flow of a household is not reduced in proportion thereto, and eventually over flow flows into the other rooms which are being heated not to save fuel cost and further produce cavitation due to fluid velocity increasing. 
     This difference is further deepened as the number of the heating-stopped room is increased, as shown in  FIGS. 11 and 12 , wherein as shown in  FIG. 12 , it is shown that in case of one room being heated, the apparatus according to the present invention approaches closely to the optimum value to practically save fuel cost and not to produce noise; however, the prior differential pressure flow valve is different greatly from the optimum value to decrease heating efficiency and produce noise due to cavitation. 
     Meanwhile, the control methods of “open valve number rate” and “open valve length rate” among the heating device, which is described in the prior art, comparing to the apparatus according to the present invention, are applied to same household for the optimum flow and actual control flow to be reviewed. 
     The parameters of “Korea Koyang shi hangshindong shin donga apartment 48 pyung type (hereinafter, referred to as “construction example”) are shown in  FIG. 13 . As shown in  FIG. 13 , even though an area of “dining room” is smaller than that of “main room+dress room” in the construction example, the dining room which has generally a large window and the numbers of the window is many and thus the heating load is large due to much heat loss to increase the optimum flow. 
     As shown in  FIG. 14 , it is shown that the apparatus according to the present invention is installed to the construction example to control a real flow and then error is 0% per room. This is caused from the fact that a total constant flow is initially controlled based on the optimum flow value per room so that the total constant flow is controlled by the amount of the optimum constant flow of the heating-stopped room and thus the design criteria is met to improve a heating efficiency for performing optimum heating and reduce cavitation. 
     However, in  FIG. 15 , the data of a constant flow, which is controlled by the method of “open valve number rate”, is shown wherein the constant flow is controlled by the driver number, without consideration at all of a room area or a heating load, and thus the actual controlled flow shows an equal value per room. 
     This result is not relevant to the optimum flow value request by the corresponding room and thus over-heating or lower-heating is caused to decrease a heating satisfaction and produce cavitation in the over-heating room. 
     Further, in  FIG. 16 , the data of a constant flow which is controlled by a prior method of “open valve length rate” is shown wherein the constant flow is controlled by considering the room area and thus the error is decreased a little bit, comparing the results shown in  FIG. 15 ; however, still over-heating or lower-heating is occurred not to maintain the optimum heating. 
     Hereinafter,  ┌ whether a temperature variation ΔT of the regional heating design criteria is satisfied ┘  based on the control methods of “open valve number rate” and “open valve length rate”, comparing to the present invention, will be described. 
     As shown in  FIG. 13 , in case where a dining room only is heated, a heating load of a dining room is 3,422 [kcal/h], and this value means the necessary request heat amount for the dining room wherein referring to  FIG. 14 , an actual control flow is 3.8[lpm], and is multiplied by 60 to convert time concept to calculate ΔT, and then ΔT is as followings. 
       3,422=(3.8×60)×1 ×ΔT  
 
     ΔT=15(° C.) 
     However, as shown in  FIG. 15 , when the flow is controlled by the “open valve number rate” method, the actual control flow of a dining room is 2.23[lpm], and at this time ΔT is as followings. 
       3,422=(2.23×60)×1 ×ΔT  
 
     ΔT=about 26(° C.) 
     Accordingly, a controlling of the flow according to “open valve number rate” method does not satisfy the temperature variation 15° C., which is shown in the regional heating design criteria. Further, in case of the actual control flow being smaller than optimum flow value, the water returning temperature is 34° C., which is remarkably lower than 45° C. shown in the regional heating design criteria, and as a result, a room temperature is not uniform though a whole room and a deviation between entrance side and exit side of the warm water is great to cause an heat unbalance. 
     Meanwhile, a case of an actual control flow being greater than the optimum flow when the flow is controlled according to “open valve length rate” control method is given as an example. 
     Referring to  FIGS. 13 and 16 , a heating load of a study room is 1,065[kcal/h], and as a result the optimum flow is 1.18; however, the actual flow is 1.88. At this time the temperature variation (ΔT) is as followings. 
       1,065=(1.88×60)×1 ×ΔT  
 
     ΔT=about 9.4 (° C.) 
     Accordingly, when flow is flowed over the optimum flow, the regional heating design criteria is not satisfied and as well enough heat exchanging with room is not made to decrease heating efficiency, thereby to increase heating cost. 
     While the invention has been shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Therefore, the scope of the invention is defined not by the detailed description of the invention but by the appended claims, and all differences within the scope will be construed as being included in the present invention.