GB2265476A

GB2265476A - Hot water supply controller

Info

Publication number: GB2265476A
Application number: GB9305658A
Authority: GB
Inventors: Takashi Nakayama; Sadao Okada
Original assignee: Rinnai Corp
Current assignee: Rinnai Corp
Priority date: 1992-03-25
Filing date: 1993-03-19
Publication date: 1993-09-29
Anticipated expiration: 2013-03-19
Also published as: KR960004852B1; DE4308770A1; GB9305658D0; GB2265476B; KR930020114A; JPH05272805A; KR940020480U; KR960005213Y1; DE4308770C2

Description

2265476 CONTROLLER OF A HOT-WATER SUPPLY This application claims the

priority of Japanese Patent Applications No. 67481/1992 filed March 25th, 1992 which is incorporated herein by reference.

This invention relates to a controller of a hot-water supply, especially to a hot-water supply which can keep the temperature of the outpouring water at a predetermined temperature by reacting to a momentary change of the temperature of the outpouring water. Many improvements have been proposed for a controller of a hot-water supply which can keep the temperature of the outpouring water at a predetermined temperature. A recently proposed one can maintain the temperature of the outpouring water at a settled temperature by controlling' combustion power from the relation between the output temperature and the settled temperature.

However, this type of the controller cannot yet deal with an after-boiling phenomenon or a cool-water sandwiching phenomenon. Here, the after-boiling phenomenon means that after a tap is closed and a water flow stops, residual heat overheats the 1 stagnant water in a heatexchanger. The cool-water sandwiching phenomenon means that cool water temporarily issues when a tap is again opened.

In order to suppress the after-boiling phenomenon and the cool-water sandwiching phenomenon, Japanese Patent Application No.3-186150 ( 186150 / 1991) proposed a bypass-mixing type of controller which has a main pipe and a bypass whose flow ratio can be adjusted according to the change of the outlet temperature of a heatexchanger. The main circuit including the main pipe passes through the heat-exchanger, but the bypass circuit includes no heat-exchanger. The adjustment of the flow ratio of the bypass to the main pipe enables the bypass-mixing type controller to alleviate the after-boiling phenomenon and the cool-water sandwiching phenomenon to a certain extent.

However, under some conditions, even the bypass-mixing type controller cannot fully prevent overheating caused by the after-boiling phenomenon or pouring a cool-water temporarily caused by the cooling-water sandwiching phenomenon. Japanese Patent Application No.3-186150 controls only the flow of the bypass circuit in order to adjust the ratio of the main, heating circuit and the bypass non-heating circuit. Thus, the flow of the main, heating 2 circuit becomes insufficient or surplus. The deficit of the main flow allows the occurrence of the after-boiling phenomenon or the cool-water sandwiching phenomenon.

A purpose of this invention is to provide a controller of a hot-water supply which can suppress the occurrence of the after-boiling phenomenon, i.e. overheating of stagnant water in a main pipe by residual heat in a heat-exchanger.

To accomplish this object, this invention proposes a controller of a hotwater supply comprising a heat-exchanger, a burner for heating the heat-exchanger, a main, heating circuit including the heat-exchanger, a bypass circuit without heat-exchanger connected at both ends ( a divergence and a confluence) to the main, heating circuit, a temperature input device for predetermining the desirable temperature of the outpouring water at a user's disposal, a proportion regulator for 4 maintaining the output temperature at a predetermined temperature given by the temperature input device by regulating the burner power in response to the change of the outpouring water flow, a flow ratio adjuster equipped at the divergence of the main circuit and the bypass circuit for changing the ratio of the bypass flow to the main circuit flow, wherein the flow ratio adjuster 3 simultaneously changes two opening degrees of a first regulating valve in the main circuit and of a second regulating valve in the bypass circuit by a driving device, a water governor is installed in an upper stream of the flow ratio adjuster for maintaining a pressure difference between the upper stream of the flow ratio adjuster and a downstream of the heat- exchanger at a constant value, a signal output device is provided in order to calculate the desirable ratio of the opening degree of the first regulating valve to that of the second regulating valve for keeping the temperature of the output water at a temperature higher than the temperature of the intake water by a certain difference and to give the calculated ratio to the driving device for deciding the opening degrees of the first and second regulating valves, the displacement of the driving devise determines the opening degrees of two valves, an increase of the displacement of the driving device induces a gradual increase of the opening degree of the second regulating valve, but the opening degree of the first regulating valve maintains a certain degree till the displacement of the driving device attains a predetermined value, then the opening degree of the first valve gradually increases according to the increment of the displacement ( see Fig.1).

4 The functions of the controller will be clarified. The temperature of the outpouring water from the hot-water supply is maintained at a predetermined temperature by the proportion regulator which regulates the burner combustion power according to the difference between the settled temperature and the output water temperature. Under the condition, the signal output device determines the opening degrees of the first and second regulating valves so that the temperature of the water at the exit of the heat-exchanger is higher than that of the intake water by a certain temperature.

Except where the temperature of the intake water is too low and the predetermined temperature is too high, it is desirable to keep the main circuit flow constant, irrespective of the bypass circuit flow in order to maintaining the water temperature at the exit of the heat-exchanger at a prescribed temperature which is higher than the Intake water temperature by a certain temperature.

When the flow ratio of the bypass circuit to the main circuit is raised within some range, the flow of the main circuit is kept constant, if the opening degree of the first regulating valve is unchanged, because the water governor maintains the pressure J difference between the intake water and the water at the confluence of the bypass and the main circuits. When the bypass flow ratio further increases beyond the range, the resistance at the confluence increases so much that the main circuit flow would be weakened, even if the pressure difference between the intake region and the confluence is kept to be a constant value by the water governor. But the opening degree of the first regulating valve shall be increased, since the bypass flow ratio has attained the value. The increment of the opening of the first regulating valve cancels the tendency of decrease of main circuit flow. Thus, the flow of the main circuit is kept constant. Since the main, heating circuit maintains a sufficient flow, overheating of excessively small amount of water in the heatexchanger by the residual heat can be avoided. The rich flow of the main circuit prevents the after-boiling phenomenon perfectly. Furthermore such a stationary, stable state can be quickly established, when the hot-water supply is again started.

The problem of the after-boiling has been solved by the controller described hereinbefore. Another purpose of this invention is to provide a controller which allows a hot-water supply to produce a hot-water of a predetermined temperature and 6 to greatly alleviate the cool-water sandwiching phenomenon, even if the temperature of the intake water is low and the predetermined temperature is too high.

To accomplish the object, this invention proposes another controller of a hot-water supply comprising a heat-exchanger, a burner for heating the heat-exchanger, a main, heating circuit including the heat-exchanger, a bypass circuit without heat-exchanger connected at both ends ( a divergence and a confluence) to the main, heating circuit, a temperature input device for predetermining the desirable temperature of the outpouring water at a user's disposal, a regulator for maintaining the output water temperature at a predetermined temperature given by the temperature input device by regulating the burner combustion power in response to the change of the outpouring water flow, a flow ratio adjuster equipped at the divergence of the main circuit and the bypass circuit for changing the ratio of the bypass flow to the main circuit flow, wherein the flow ratio adjuster simultaneously changes two opening degrees of a first regulating valve in the main circuit and a second regulating valve in the bypass circuit by a driving device, a water governor is installed in an upper stream of the flow ratio adjuster for 7 maintaining the pressure difference between the divergence and confluence at a constant pressure, a signal output device is provided in order to calculate the desirable ratio of the opening degree of the first regulating valve to that of the second regulating valve for keeping the temperature of the output water at a temperature higher than the temperature of the intake water by a certain difference and to give the driving device the calculated ratio for deciding the opening degrees of the first and second regulating valves, the displacement of the driving device determines the opening degrees of the two valves; when the displacement changes in a range from 0 to a preset value, the second regulating valve is closed; when the displacement exceeds the preset value, the opening degree of the second regulating valve increases in proportion to the increment of the displacement; when the displacement exceeds the preset value, the opening degree of the first regulating valve is kept to be constant so as to maintain a constant main circuit flow; and when the displacement is less than the preset value, the opening degree of the first regulating valve decreases in proportion to the decrement of the displacement.

The functions of the controller will now be clarified in 8 details. In winter, the temperature of the intake water entering the heat- exchanger is sometimes too low and the predetermined temperature is often too high. In such an extraordinary case, a prior controller would not supply a sufficient quantity of hot water, even if the burner power were settled at a maximum value. On the contrary, this invention lets the signal output device reduce the opening degree of the first regulating valve at which the water temperature at the outlet of the heat-exchanger is maintained at a temperature higher than that of the intake water by a certain value. Namely, this invention can keep the outpouring water temperature at the determined temperature by reducing the opening degree of the first valve which controls the flow of the main, heating circuit, in spite of cold intake water.

Otherwise, when the temperature of the intake water is warm enough and the performance of the heat-exchanger has a surplus power, the flow of the main, heating circuit is kept to be constant similar to the previously mentioned controller. Furthermore, this controller allows a hot-water supply to avoid the occurrence of the cool water sandwiching phenomenon when the tap is again opened after a pause, because the temperature of the outpouring hot-water is kept at the preset value in spite of too 9 cool intake water and too high preset temperature in winter and because the flow of the main circuit is always kept at a pertinent amount.

This invention will be further explained by referring the drawings exhibiting embodiments of this invention.

Fig. 1 is% a scbematic view of a fundamental structure of a controller of a hot-water supply according to one embodiment of this invention.

Fig.2 is a schematic view of an embodiment of this invention.

Fig.3 is a sectional view of a unified structure of a first regulating valve and a second regulating valve.

Fig.4 is a perspective view of the first regulating valve.

FIg.5 is a graph demonstrating the relation between a rotation angle of a valve shaft and the flows of a main circuit and a bypass circuit when the first regulating valve and second regulating valve are simultaneously adjusted.

Fig.6 is a graph showing the relation between the rotation angle of the valve shaft (screw shaft) and the flow ratio of the bypass circuit to the main circuit.

Fig.7 is a block diagram of a gas proportion governor.

Fig.8 is a block diagram of a signal output device.

Fig.9 is a sectional view of another example of a first regulating valve.

Fig. 10 is a sectional view of Fig. 9 taken along line X-X.

A fundamental structure of a controller is shown by Fig.l. A main, heating circuit (1) and a bypass circuit (2) are pipes for leading water. Water is divided at a divergence into the main and bypass circuits. The division ratio of the main circuit flow and the bypass circuit flow is determined by a flow ratio adjuster (3). A water governor (4) is installed at an upper stream of the divergence. The main, heating circuit (1) is provided with a heat-exchanger (10) which is heated by a gas burner (B). The combustion power of the gas burner is changed by a gas proportion valve (G). A first regulation valve (31) is equipped in the main, heating circuit (1). A second regulating valve (32) is equipped in the bypass circuit (2). The flow ratio adjuster (3) includes a signal output device (30) and a driving device (M) for varying the opening degrees of the first and second regulating valves (31) and (32). A gas proportion governor (C) controls the burner power through a gas proportion valve (G) by comparing a temperature of hot-water at a downstream of a confluence of the main and bypass -1 circuits with a preset temperature.

To achieve the foregoing objects and in accordance with the purpose of the invention, embodiments will be broadly described herein.

Fig.2 shows an embodiment of this invention. A water intake circuit (40) is divided at a divergence into a main, heating circuit (1) including a heat-exchanger (10) and a bypass circuit (2) without a heat-exchanger. A flow ratio adjuster (3) installed at the divergence to the circuits distributes intake water to the main, heating circuit (1) and the bypass circuit (2). An intake water temperature sensor (Tci) is furnished at the water intake circuit (40) for measuring the temperature of the intake water. An output water temperature sensor (T2) is provided at a downstream of a confluence of the main and bypass circuits for monitoring the temperature of the hot water prepared by the supply. The combustion power of the gas burner (B) heating the heat-exchanger (10) is controlled by the gas proportion valve (G). In the embodiment, a feed-back type of gas proportion governor is used as shown in Fig.7. A temperature input device (S) settles a desirable temperature of the output hot-water at a mercy of a user. Comparing the actual output water temperature monitored by the 12 e output water temperature sensor %) with the preset temperature in the temperature input device (S), the gas proportion governor (C) calculates an optimum opening degree of the gas proportion valve (G), and gives the gas proportion valve (G) a signal corresponding to the calculated optimum opening degree. Detailed explanation of the relation between the gas proportion value and the burner power is omitted, because it has been well known by the skilled man.

A most important part of the embodiment is the flow ratio adjuster (3). The flow ratio adjuster (3) comprises a driving device (M) and a signal output device (30). The driving device (M) simultaneously drives a first regulating valve (31) determining the opening degree of an inlet (11) of the main, heating circuit (1) and a second regulating valve (32) determining the opening degree of an inlet (21) of the bypass circuit (2). The signal output device (30) provides the driving device (M) with a driving signal by taking. account of the intake water temperature of the sensor (Tcl), the output water temperature of the sensor (T) and the preset temperature of the temperature input device (S). An integrated valve (V) contains the first regulating valve (31), the second regulating valve (32) and a water governor (4). The water governor (4) has a first cavity (43a), a second cavity (43b), a diaphragm (42) 13 parting the cavities (43a) and (43b), a spring (44) pushing the diaphragm toward the second cavity (43b), a valve element (46) fixed on the diaphragm (42) and a conical spring (45) for supporting the valve element (46). The first cavity (43a) communicates with the bypass circuit (2) through a passageway (43). The second cavity (43b) communicates both an inlet (41) of the integrated valve (V) succeeding the water intake circuit (40) and a cylindrical valve space (33) leading to the main and bypass circuits (1) and (2). The valve space (33) holds the first and the second regulating valves (31) and (32). Since the elastic force of the springs balances with the pressure difference between the first and second cavities (43a) and (43b), the pressure difference between the water intake circuit (40) and the bypass circuit (2) is kept to be a constant value by the water governor (4). As long as the hydraulic resistance from the second cavity (43b) to the confluence (N) is constant, the flow of hot water is maintained constant, irrespective of the fluctuation of the initial pressure of the intake circuit (40).

As shown by Fig.3, the first regulation valve (31) and the second regulation valve (32) are driven commonly by a valve shaft (34) which is able to move in a longitudinal direction in the cylindrical valve space (33). The valve shaft (34) has a screw part 14 (35) at an end which engages with a female screw formed on an inner surface of a hole (39) of the valve (V). The driving device (M) fixed at a flange (38) around the hole (39) has an output shaft (37) which is coupled to the screw part (35) of the valve shaft (34). Only rotation can be transmitted from the driving device to the valve shaft (34) but no axial displacement is transmitted to each other, since the valve shaft (34) is not fixed to the output shaft (37). When the valve shaft (34) is rotated by the driving device (M), the valve shaft (34) moves also in the axial, longitudinal direction by the screw-coupling, although the output shaft (37) of the driving device (M) is not displaced in the longitudinal direction. Namely, the valve shaft (34) rotates and progresses or regresses at the same time. The first regulating valve (31) is substantially a valve element fixed to the valve shaft (34). The first regulating valve (31) moves and rotates in the cylindrical valve space (33) in the vicinity of the inlet (11) of the main, heating circuit (1). Rotation and displacement of the first regulating valve (31) vary the opening degree of the main, heating circuit (1). Sometimes the inlet (11) is fully choked. At other times, the inlet (11) is opened. The opening degree can be continuously controlled by the first regulating valve (31). The second regulating valve (32) is a conical valve element slidably fitted to the valve shaft (34). The second regulating valve (32) also rotates and displaces with the valve shaft (34), when it is separated from a valve seat.

The first regulating valve (31) as shown in Fig.4 has a cylindrical surface, an outer circular surface and an inner skew surface which is slanting to the axial direction. The scope of rotation of the output shaft (37) ( i.e. the valve shaft (34))of the driving device (M) is restricted within 270 degrees. The inner skew surface and the cylindrical surface change the opening degree of the main, heating circuit (1) according to the rotation of the valve shaft (34) by varying the area closed by the cylindrical surface of the first regulating valve (31). As shown by Fig.5, when the rotation angle of the valve shaft (34) increases from 0 degree to 90 degrees, the opening degree of the inlet (11) to the main circuit (1) is raised from an initial definite value to another definite value, proportionally. When the rotation angle of the valve shaft (34) varies between 90 degrees and 270 degrees, the opening degree of the inlet (11) is kept to be a constant value. Dotted line 1 demonstrates the opening degree of the first regulating valve (31). Therefore, when the tap (J) equipped to the output circuit is fully opened, the flow of the main circuit (1) varies as doted line 1 16 according to the rotation of the valve shaft (34).

On the other hand, the second regulating valve (32) as shown in Fig. 3 has a conical surface which can tightly fit in a valve seat formed in the valve space (33). The bypass circuit (2) lies in a downstream of the valve seat. The flow of the bypass circuit can be varies by the movement of the second regulating valve (32). The second regulating valve (32) is not fixed to the valve shaft (34), but is slidably assembled. The valve seat precedes the inlet (21) of the bypass circuit (2). The full stroke of the slide of the second regulating valve (32) is designed to be one third of the full displacement of the valve shaft (34). The second regulating valve (32) is elastically pushed toward the inlet (21) by a spring (36) whose other end is held by the first regulating valve (31). The forehead of the second regulating valve (32) is conical. A disc- shaped flange succeeds the conical forehead. The diameter of the flange is bigger than the inner diameter of the valve seat before the inlet (21). When the rotation angle of the valve shaft (34) is 0, the spring (36) is shortened by one third of the full stroke of the valve shaft (34) by the pressure acting between the valve seat and the second regulating valve (32). When the rotation angle of the valve shaft (34) varies from 0 degree to 90 degrees, 17 the second regulating valve (32) tightly closes the bypass circuit (2). When the rotation angle of the valve shaft (34) increases from degrees to 270 degrees, the second regulating valve (32) gradually separates from the valve seat and the opening degree of the bypass circuit (2) is heightened in proportion to the rotation angle deviating from 90 degrees. The opening degree of the second regulating valve (32) is exhibited by doubly-dotted line 2 in Fig.5.

Thus the flow of the bypass circuit (2) similarly changes as doubly-dotted line 2, when the tap (J) of the output circuit is fully opened.

The first regulating valve (31) and the second regulating valve (32) allocate the opening degrees of dotted line 1 and doubly-dotted line 2 to the main, heating circuit (1) and the bypass circuit (2) in response to the change of the rotation angle of the valve shaft (34) displaced by the driving device (M). When, the output tap (J) is fully opened, the flow of each circuit is in proportion to the opening degree of them. Thus the total flow of hot water varies as shown by solid line 3, according to the rotation of the valve shaft (34). Solid line 3 is a sum of dotted line 1 and doubly-dotted line 2. Slower increase of the total flow between 0 degree and 90 degrees of the rotation angle results from the 18 similar increase of the main flow. Faster increase of the total flow between 90 degrees and 270 degrees is caused by the rapid increase of the bypass flow to the contrary. The flow ratio of the bypass circuit (2) to the main, heating circuit (1), i.e. bypass flow ratio changes as solid line 3 in Fig.5, irrespective of the opening degree of the output tap (J). The stability of the bypass flow ratio regardless of the state of the tap (J) is caused by the fact that the water governor (4) maintains the difference of the pressures between the water intake circuit (40) and the confluence (N) to be constant despite the fluctuation of the pressure of the water intake circuit (40). Thus, the ratio of the bypass circuit (2) to the main, heating circuit (1) is solely determined by the driving device (M) which moves simultaneously the first regulating valve (31) and the second regulating valve (32).

Then the signal output device (30) will now be explained. As demonstrated in Fig.8, the signal output device (30) has a first calculator (30a), a second calculator (30b) and a rotation angle determiner (30c). Receiving the intake water temperature (Teil) from the intake water temperature sensor (Tci) and the preset temperature (S,) from the temperature input device (S), first calculator (30a) adds 50 degrees to the intake water 19 temperature (To I) and subtracts the preset temperature (S,) from the sum ( 50 + To,). Thus, the first calculator (30a) obtains ( Tol + 50t - S,). The second calculator (30b) subtracts the intake water temperature (Tol) from the preset temperature (S,) and obtains the difference ( S, - To,). Receiving ( Tol + WC S,) and ( S, - To,) from the first and second calculators, the rotation angle determiner (30c) calculates a desirable rotation angle of the valve shaft (34). The output signal of the determiner (30c) is sent to the driving device (M) which rotates the valve shaft (34).

The opening degree of the gas proportion valve (G) is adjusted so as to equalize the output water temperature with the preset temperature (SJ of the temperature input device (S). If the water flow, the preset temperature, the intake water temperature and the thermal efficiency of the heat-exchanger have been determined, the combustion power of the gas burner (B) is constafit, irrespective of the flow ratio between the main, heating circuit (1) and the bypass circuit (2), as long as the kind of gas is the same. Therefore, sole settling of the opening degree of the gas proportion valve (G) allows the water to be heated exactly up to the preset temperature. Feedback controlling is employed to the gas proportion governor (C) in order to equalize the water temperature with the preset temperature exactly.

The signals output device (30) decides the preferable temperature of the water at the outlet of the heat-exchanger (10) to be a temperature by 50 degrees higher than the intake water temperature (Tc)l) and calculates the desirable rotation angle of the valve shaft (34) in order to keep the output water temperature at the preset value. When the desirable temperature (S,) is once settled, the intake of water is constant, and the temperature of the outlet of the heat-exchanger (10) is 50'C higher than the intake water temperature (Ttil), the ratio of the main, heating circuit (1) to the bypass circuit (2) will be equal to the ratio of ( S, Tci I) to ( Tc), + 50T S,). In this embodiment, the ratio of the output of the second calculator (30b) to that of the first calculator (30a) is equal to the aforementioned ratio. Thus, the bypass ratio given by the rotation angle determiner (30c) satisfies the above requirements. Under the suitable-settled bypass ratio, an assembly of the gas proportion governor (C) and the gas proportion valve (G) controls the combustion power of the burner with feedback operations.

Adequate control of the flow of the main, heating circuit (1) enables the heat-exchanger (10) to avoid overheating or 21 underheating the water of the main, heating circuit (1), since the main flow is maintained so as to keep the output water temperature at ( To, + 50t) in the embodiment.

Especially, the water governor (4) keeps the constant pressure difference between the confluence (N) communicating with the first cavity (43a) and the valve space (33) communicating with the second cavity (43b). The opening degree of the inlet (11) is varied along dotted line 1 in Fig.5 according to the rotation of the first regulating valve (31). Shortage of the flow of the main, heating circuit (1) can be avoided even if the bypass ratio is raised. Otherwise the main flow is kept to be constant, when the bypass ratio is increased.

Even in the case of too cool intake water and too high preset temperature, hot water of the preset temperature can be obtained by controlling the flow of the main, heating circuit (1) to be reduced to some extent and the bypass flow to be zero. Such control can be easily realized by setting the rotation angle between 0 degree to 90 degrees as shown in Fig. 5. Thus, this invention can suppress an occurrence of the cool water sandwiching phenomenon even in such a difficult case.

Another shape of a first regulating valve is also 22 1 available, sincethe requirement imposed upon the first regulating valve (31) is varying the flow of the main, heating circuit (1) according to dotted line 1 in Fig.5. Fig.9 and Fig.10 exhibit another example of a first regulating valve (31). The valve element is a simple columnar body which can be displaced in an axial direction by the valve shaft (34). But the wall of an inlet (11) communicating with the main, heating circuit (1) has two special holes. A rear hole (Ila) is a half circle. A front hole Ulb) is a small circle. When the rotation angle is 270 degrees, the first regulating valve (31) recedes into the rear cavity and two holes are fully released. As the rotation angle decreases, the first regulating valve (31) progresses toward the driving device (M). The first regulating valve (31) occults the rear half circle hole (Ila) fully at the rotation angle of 0 degree. Between the rotation angle of 90 degrees and 0 degree, the valve gradually occults the half circle hole (11a). Both holes (11a) and (11b) are totally released between 90 degrees and 270 degrees of the rotation angle. The hole (11b) is always opened. Therefore, the flow of the main, heating circuit changes in accordance with dotted line I in Fig. 5. The sizes and shapes of the holes (11a) and (Ilb) are determined so as to equalize the main, heating circuit flow when the tap (J) is 23 fully opened to the maximum value of dotted line 1 of Fig. 5.

24

Claims

1. A controller of a hot-water supply comprising: a heat-exchanger for heating intake water, a burner for heating the heat-exchanger, a main, heating circuit including the heat-exchanger in which intake water flows, a bypass circuit without the heat-exchanger which is connected to the main, heating circuit at a divergence and a confluence for bypassing a part of intake water, a temperature input device for presetting a desirable temperature of outpouring water at a user's disposal, a proportion regulator for keeping the outpouring water temperature at a preset temperature designated by the temperature input device by regulating burner power in response to the change of the outpouring water flow, and a flow ratio adjuster provided at the divergence for changing the ratio of the bypass flow to the main, heating circuit flow so as to keep the water temperature at an outlet of the heat-exchanger at a predetermined temperature, characterized in that the flow ratio adjuster (3) at the divergence can simultaneously change two opening degrees of a first regulating valve (31) communicating with the main, heating circuit (1) and of a second regulating valve (32) communicating with the bypass circuit (2) by a driving device (M), a water governor (4) is provided- in an upper stream of the flow ratio adjuster (3) for maintaining a pressure difference between the upper stream of the flow ratio adjuster (3) and a downstream of the heat-exchanger (10) at a constant value, a signal output device (30) is furnished for calculating the desirable ratio of the opening degree of the first regulating valve (31) to the opening degree of the second regulating valve (32) for keeping the temperature of the output water at a predetermined temperature higher than the temperature of the intake water by a certain difference and for giving the driving device (M) the calculated ratio for deciding the opening degrees of the first regulating valve (31) and the second regulating valve (32), the displacement of the driving device (M) determines the opening degrees of the two valves (31) and (32) simultaneously, an increase of the displacement induces a gradual increase of the opening degree of the second regulating valve (32), but the opening degree of the first regulating valve (31) maintains a certain degree till the displacement of the driving device attains 26 a predetermined value, and then the opening degree of the first regulating valve (31) gradually increases according to the increment of the displacement.

2. A controller of a hot-water supply comprisin a heat-exchanger for heating intake water, a burner for heating the heat-exchanger, a main, heating circuit including the heat-exchanger in which intake water flows, a bypass circuit without the heat-exchanger which is connected to the main, heating circuit at a divergence and a confluence for bypassing apart of intake water, a temperature input device for presetting a desirable temperature of outpouring water at a user's disposal, a proportion regulator for keeping the outpouring water temperature at a preset temperature designated by the temperature input device by regulating burner power in response to the change of the outpouring water flow, and a flow ratio adjuster provided at the divergence for changing the ratio of the bypass flow to the main, heating circuit flow so as to keep the water temperature at an outlet of the heat-exchanger at a predetermined temperature, g:

27 characterized in that the flow ratio adjuster (3) at the divergence simultaneously changes two opening degrees of a first regulating valve (31) communicating the main, heating circuit (1) and of a second regulating valve (32) communicating with the bypass circuit (2) by a driving device (M), a water governor (4) is installed in an upper stream of the flow ration adjuster (3) for maintaining a pressure difference between the divergence and the confluence at a constant pressure, a signal output device (30) is equipped for calculating the desirable ratio of the opening degree of the first regulating valve (31) to the second regulating valve (32) for keeping the temperature of the output water at a temperature higher than the temperature of the intake water by a certain difference and for giving the driving device (M) the calculated ratio for deciding the opening degrees of the first regulating valve (31) and the second regulating valve (32), the displacement of the driving device (M) determines the opening degrees of the two valves (31) and (32); when the displacement changes in a range from 0 to a predetermined value, the second regulating valve (32) is closed; when the displacement exceeds the predetermined value, the opening degree of the second regulating valve (32) increases in proportion to the increment of the 28 displacement; when the displacement exceeds the predetermined value, the opening degree of the first regulating valve (31) is kept to be constant so as to maintain a constant main circuit flow; and when the displacement is less than the predetermined value, the opening degree of the first regulating valve (31) decreases in proportion to the decrement of the displacement.

3. A controller of a hot-water supply as claimed in claim 2, wherein the displacement of the driving device (M) is a rotation angle of a valve shaft driven by the driving device (M) in response to an output signal sent from the signal output device (30), the scope of rotation is restricted within a range from 0 degree to 270 degrees, and the predetermined value at which the relation between the opening degrees and the rotation angl changes is 90 degrees.

4. A controller of a hot-water supply as claimed in claim 3, wherein the first regulating valve (31) and the second regulating valve (32) are moved together in an axial direction by the rotation of the valve shaft of the driving device (M), the second regulating valve (32) is elastically pushed toward a closing direction and shuts the bypass circuit (2) in a range between 0 degree and 90 degrees by the elastic force, and the second 29 regulating valve (32) is moved toward an opening direction in proportion to the increment on the rotation angle when the rotation angle exceeds 90 degrees.

5. A controller for a hot-water supply substantially as hereinbefore described with reference to and as shown in the accompanying drawings.