GB1592008A

GB1592008A - Heating system with one or more supply outlets

Info

Publication number: GB1592008A
Application number: GB48748/77A
Authority: GB
Original assignee: Tour and Andersson AB
Current assignee: Tour and Andersson AB
Priority date: 1977-01-28
Filing date: 1977-11-23
Publication date: 1981-07-01
Also published as: SE403827B; DK555777A; DE2803655A1; FI780076A; ATA830077A; DK146269C; FR2379035A1; SE7700892L; IT1091838B; IT7819229A0; DK146269B

Description

(54) A HEATING SYSTEM WITH ONE OR MORE SUPPLY OUTLETS (71) We, TOUR & ANDERSSON AKTIEBOLAG, a Company limited, organized under the laws of the Kingdom of Sweden, of Svardlangsvagen 46, Johanneshov; Stockholm, Sweden, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to a heating system capable of supplying heated water to one or more outlets.Such heating systems include a heat exchanger for heating water to be supplied to the outlet or outlets and according to prior proposals including a heat radiator system, a water tank forming part of the heat exchanger may be built into a hot water generator so that the piping through which hot water formed in the generator is fed to the heat radiator system, perhaps after shunting with colder return water, comprises or is connected in parallel to the primary side of the heat exchanger. In the secondary side of the exchanger cold water passes through the tank and is heated by the primary side for supply to the outlet or outlets. Alternatively, the water tank may be separate from the hot water generator and is heated on a primary side by hot water in pipework extending from the hot water generator in a system parallel to the heat radiator system.The water on the secondary side of the heat exchanger has commonly been supplied under pressure from the mains water supply. For reasons of combustion economy, it is desirable that the water in the hot water tank should have a very high temperature, but the use of such a high temperature in the outlet heating system may be inconvenient because the users of water from the outlet(s) may burn their hands if the water is too hot.

It is often desired that there should be plentiful supply of hot water in the hot water tank, but on the other hand, it is not desired that the hot water tank should be too large or expensive.

The requirement for reasonable dimensions of the hot water tank is especially pronounced when the hot water tank is built into the hot water generator as aforementioned. In order to make sure that the water from the outlet will not be too hot, and also to cut down the size and cost of the tank, it has been proposed to heat the water in the tank to a high temperature and then to dilute this water by colder water to obtain a larger quantity of heated water for use, even though this will have a lower temperature than that of the water actually in the secondary side of the exchanger.To obtain this dilution it has been proposed to provide a three-way valve in the feeder conduit from the exchanger to the supply outlet or outlets which may be thermostatically controlled by the temperature of the water from the valve outlet to maintain an at least approximately constant temperature of the water to the supply outlet or outlets. The value of this constant temperature, of course, may be adjustable manually or in any other way. The three-way valve receives hot water from the secondary side of the heat exchanger through one inlet and cold water from a cold water source such as mains supply through a second inlet; water from both inlets is mixed in the valve to provide the water of a lower temperature. The cold water is fed to the three-way valve simultaneously with water being drawn from the supply outlet or outlets.

There is also a more advanced arrangement including a three-way valve in which the or each supply outlet is provided in a loop conduit to direct water past the supply outlet or outlets and back to the three-way valve when the supply outlet(s) is closed. In such a loop conduit it is usual to provide a pump to slowly circulate the water when there is no tapping off from the supply outlet(s). The advantage of this advanced arrangement is that, even when the supply outlet(s) is an appreciable distance from the heat exchanger, the water in the loop conduit should retain the desired temperature.In fact, where no loop conduit is provided, as described in the immediately preceding paragraph, a problem has been that the water in the feeder conduit is stationary during periods of time when no water is being drawn from the supply outlet(s), so that it cools down and water of the desired temperature cannot be tapped off until some time after opening a supply outlet and the water which has cooled down has been drawn off.It is apparent, of course, that some cooling of the water may occur during its circulation in the aforementioned loop conduit, and in order to maintain the water in the loop conduit at the desired temperature, the return water may be fed not only to the three-way valve cold water inlet but also to the cold water inlet of the secondary side of the heat exchanger, hot water being simultaneously fed from the secondary side of the heat exchanger to the three-way valve.

It has been proposed to save fuel in a heating system with a hot water tank by shutting off the supply of hot water from the tank during given periods of time of the day, so-called "cold periods", so that no hot supply outlet water is available except during the intermediate periods, the so-called "hot periods". There have been many different proposals to this end but none so far has been entirely successful.

One such proposal has been to shut off the primary side of the heat exchanger. The disadvantage of this, where the heat exchanger primary side comprises the heat radiator system as aforedescribed, is that the supply of heated water to the radiator system will also be shut off and this is not usually acceptable.

Shutting off the primary side of the heat exchanger in a system where the heat exchanger primary side is connected in parallel as aforedescribed will mean that during a subsequent cold period, warm water will nevertheless be available from the supply outlet(s), although probably of a successively decreasing temperature. More importantly, however, there is the further disadvantage that when heat is again supplied to the primary side of the heat exchanger, the water in the secondary side will likely be cold, whether it has cooled down during the cold period or has been tapped off and replaced by cold water. Often where large hot water tanks are necessary, such as in apartment blocks, but also in houses, several hours are needed before cold water being heated in the secondary side acquires the desired temperature.

It has alternatively been proposed to shut off the secondary side of the heat exchanger during the cold periods so that no water is supplied to the supply outlet(s). This has the disadvantage that if the supply outlet(s) is left open during a cold period, when the supply of water to the outlet or outlets is resumed there is a likelihood of wasteful supply of hot water, and of overflows with consequent damage.

It is an object of the present invention to provide a heating system in which the supply of heated water to the supply outlet or outlets may be selectively shut off but in which the aforementioned disadvantages are alleviated.

According to the present invention there is provided a heating system capable of supplying heated water to at least one supply outlet, the system comprising a heat exchanger adapted to receive cold water to be heated by the exchanger; a thermostatically controlled three-way valve connected to receive heated water from the heat exchanger at a first inlet and cold water at a second inlet, the valve having an outlet which is connected to said at least one supply outlet and is capable of receiving water from one or both inlets according to the temperature of the water in the valve outlet determined by the thermostat of the valve; and controlled means operable independently of the temperature of the water in the valve outlet to close the first inlet while the second inlet remains open to the valve outlet, whereby only water from the second inlet is directed to the supply outlet while the valve is under the control of the controlled means.

By the present invention a heating system is provided in which water is available for tapping off through the or each supply outlet at all times, but when the three-way valve is under the control of the controlled means only cold water will be supplied and yet as soon as said control ceases, hot water is available for supply.

The heat exchanger of the system of the present invention will usually comprise a water tank and have a primary side which is adapted to receive heating medium therethrough, and wherein the cold water is received in a secondary side of the exchanger, to be heated by the heating medium, and the secondary side thereof may conveniently be heated, as aforedescribed, by the pipework of a heat radiator system or by pipework which runs parallel to the pipework of a heat radiator system.

Preferably, the controlled means is time controlled whereby during one or more preselected periods of the day (the cold periods) it acts to override the thermostat to maintain the first inlet closed. The thermostat may be selectively adjustable to vary the temperature in the water outlet when not under the control of the controlled means, by acting to adjust the relative flows of water through the inlets.

The adjustment may, for example, be by manual means to select a particular temperature of water flowing from the valve outlet to the supply outlet or outlets.

It is convenient to arrange that the second inlet is progressively opened as the first inlet is progressively closed, and vice versa.

In a preferred embodiment of the heating system the thermostat of the three-way valve is capable of applying a mechanical force to a valve body to open and close the first and second inlets in response to variation of the temperature of the water in the valve outlet, and conveniently the controlled means is adapted to bias the thermostat and thereby the valve body to close the first inlet. In such an embodiment the controlled means may comprise an electro-thermal motor mounted on the valve and mechanically engaged with the thermostat. The motor preferably comprises a heating element capable of transferring heat to means whose overall length varies on heating, for example a bi-metallic spring member, to bias the thermostat and the valve body to close the first inlet.Alternatively, the controlled means may comprise electromagnetic means mounted on the valve and operable to mechanically bias the thermostat and valve body to close the first inlet. The electro-magnetic means may have an armature which, when energized, engages the end of the thermostat remote from the valve body to provide said biasing.

Two embodiments of a heating system in accordance with the present invention will now be described by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows the first embodiment of the heating system including a three-way valve and supply outlets; Figure 2 shows the second, more advanced, embodiment of the heating system in which the supply outlets are provided in a loop conduit, and Figure 3 shows a cross-sectional view of a three-way valve and controlled means suitable for use in either embodiment.

The two embodiments of the invention are described and illustrated in connection with a heating system including a separate heat exchanger heated by hot water as aforedescribed, but it is to be understood that the invention is equally applicable to a heating system in which the heat exchanger is built into a hot water generator, such as a boiler, for a heat radiator system.

A three-way valve is designated generally at 16 in Figures 1 and 2 and supply outlets at 18 for tapping-off water. A conduit 10 in Figure 1 leads from a source of hot water such as a boiler (not shown in the drawing) to a primary system, designated 11, of a heat exchanger tank 12, and water in the system 11 is then returned to the source of hot water through the conduit 13.

A secondary system, designated 14, of the heat exchanger is connected so that water in the system 14 is heated by hot water in the primary system 11, and can flow through a conduit 15 connected to a three-way valve 16. A feeder conduit 17 leads from the three-way valve to carry warm water to supply outlets 18. A conduit 19 leads from a water delivery network e.g. mains water supply, and has a first conduit 20 connected to the three-way valve 16 and a second conduit 21 supplying water to the secondary system 14.

The features so far described are already known and function in the following way: It is assumed that the heat exchanger has been operative for a sufficient period to have heated the water in the secondary system 14 to a desired temperature. The water in the feeder conduit 17 of Figure 1 is stationary and, whether or not this water has earlier been heated, it will have a temperature that is close to the temperature of its surroundings, i.e.

room temperature. When one of the outlets 18 is opened only cool water in the conduit 17 will initially flow from the outlet but subsequently hot water from the secondary side of the heat exchanger 12 flows into the feeder conduit 17 through the three-way valve 16. It is known for the valve to be thermostatically controlled so that a constant temperature of the output water to the conduit 17 is automatically provided for; when hot water from the secondary system 14 of the heat exchanger 12 gives the water in the conduit 15 a too-high temperature, the thermostat of the valve 16 will adjust the valve so that the relative flows of water into the three-way valve from the conduit 15 and from the conduit 20 are varied to maintain the desired temperature of the water from the valve outlet.

A delay will thus usually occur before water of the desired temperature can be drawn off from one of outlets 18.

This waiting period may be avoided by means of the more advanced system shown in Figure 2. This differs from the arrangement shown in Figure 1 in that the conduit 17, serving the outlets 18, has been extended to form a loop having a feeder conduit 17' and a return conduit 17", a pump 22 being provided at a suitable location in the loop to slowly circulate the water around the loop. This may significantly alleviate the heat loss of water in piping leading from the valve to the supply outlets so that water in the feeder conduit 17' will be at least at approximately the desired temperature constantly while the thermostat in the valve 16 controls it.Of course, it is not possible to completely avoid a small transfer of heat from the conduits 17' and 17" in the loop and water in the conduit 20' completing the loop will usually be slightly cooler than water in the feeder conduit 17' even when the outlets 18 are closed. This difference of temperature is compensated for by the thermostat of the valve 16 which will cause a small quantity of hot water to be fed from the secondary system 14 of the heat exchanger 12 simultaneously as a corresponding amount of water in the return conduit 17" is directed to the secondary system 14 through the conduits 20" and 21, When warm water is drawn off from one or more of the outlets 18, the amount of water passing through the return conduit 17" will decrease and the movement of water in the conduit 20" mav reverse its direction, but in any event the desired quantity of hot water will be fed from the secondary system 14 through the conduit 15 to the valve 16. The thermostat of the valve 16 will adjust the flow of water so that the temperature of the water supplied to the feeder conduit 17' is maintained at the desired value.

From a review of the heating systems described with reference to Figure 1 and Figure 2 it will be seen that there is a possibility of the three-way valve 16 shutting off the hot water supply from the conduit 15 and simultaneously fully opening the supply of cold water to the conduit 17 from the mains 19 through the conduit 20 in Figure 1 or 20', 20" in Figure 2.

In order to provide this facility, the valve 16 in the two embodiments of the present invention has a thermostat 31 (Figure 3) which is not connected to fixed parts inside the valve, e.g. the valve housing, but is movable therein with a valve body capable of opening and closing the hot and cold water inlets of the valve. The thermostat is also in contact with means 38 capable of transmitting a mechanical bias force which is controlled by means 49, preferably providing a time control.The means 38 supports the thermostat 31 at all times and when the thermostat is under the control of the means 49 during the cold periods, the bias force will be so strong that no matter how strongly the thermostat opposes it due to the change in water temperature in the valve, the thermostat 31 will be forced to displace the valve body to close the hot water inlet and allow water through the valve only from the cold water inlet.

The three-way valve 16 shown in Figure 3 has three ports 26, 27 and 28 in a housing 36.

In the arrangements shown in Figures 1 and 2, the port 26 is utilised as an outlet and is connected to the feeder conduit 17 in Figure 1 or 17' in Figure 2. The port 27 is utilised as a first inlet and connected to the secondary side 14 of the heat exchanger 12 via the conduit 15. The port 28 is utilised as a second inlet connected to the cold water supply conduit 20 in Figure 1 or 20' in Figure 2. A valve part 30 of the valve body is capable of sealing against a valve seat 29 to close the port 27, and a shaft 32 connects or contacts the valve part 30 to the thermostat 31. The valve body comprises the parts 30, 32 and 33 and the thermostat 31 is also engaged by the cross-arm member 33, between whose arms water may pass essentially freely.The cross-arm member 33 is engaged by an under bias compression from a spring 34 housed within a cylindrical spring casing 35, the bias compression having such a direction that the spring 34 tends to increase the opening between the valve part 30 and the seat 29. The action of the thermostat 31 is that, when heated, it tends to displace the shaft part 32 in the opposite direction, i.e. against the action of the spring 34, thus tending to decrease the valve opening 29-30 and, when cooled, tends to act in the same direction as the spring 34.The thermostat 31 can be washed by a mixture of water from both ports 27 and 28 (if both are open) in the arrangements shown in Figures 1 and 2, which is composed of cold water from the mains 19 in Figure 1 or return water from the conduit 20' in Figure 2, and of hot water from the conduit 15, and the position of the valve part 30 in relation to the valve seat 29 will principally be determined by the temperature of this mixture.

As previously suggested, the thermostat 3 1 hovers freely in the valve in the sense that it is not rigidly connected to any part of the valve casing 36. One end of the thermostat abuts one end of the shaft 32 and the other end of the thermostat engages one end of a rod 37 of the controlled means 38, which will be further described below.

As shown in Figure 3, the controlled means 38 comprises a cylindrical casing 39 with a flat cover 40 screwed thereto, from which pressure means in the form of a stud 41 extends inwardly into the casing. At its remote end the stud 41 carries a disc 42 forming a first seat for bimetallic means whose dimensions will vary according to its temperature. Preferably the bimetallic means is in the form of a helical spring 43 of a bifilaric material whose other end engages a spring seat 44 at the other end of the rod 37.

The bi-metallic means 43 will consequently be subjected to a change of shape dependent upon its temperature, and, in order to vary the temperature, it is surrounded by a heater winding, comprising a resistance wire coil 45 wound on a tubular coil carrier 46. The coil 45 is electrically connected to a power supply 48 via the control means 49 which operates a switch to close the electrical circuit 47.

When the switch of the control means 49 is closed so that electrical current can flow to the coil 45, the temperature of the coil is raised to increase the temperature of the bi-metallic means 43. When the bi-metallic means 43 is heated it expands and extends in its axial direction; it contracts in the axial direction when the current is cut off. As the bi-metallic means 43 is rigidly supported at its one end against the first seat 42, its other end (the end resting against the spring seat 44) will be displaced when the bi-metallic means expands or contracts and this displacement moves the rod 37, the thermostat 31 and the valve body.

When the bi-metallic means is heated the force acting upon the valve body is so strong that the valve opening 29-30 is completely closed independently of any changes in shape of the thermostat 31. When the valve opening 29-30 is closed, the temperature sensed by the thermostat 31 will drop and any consequential adjustment of the thermostat is absorbed by the bi-metallic means 43 to maintain the opening closed while the valve is controlled by the control means 49. At the end of the control period the coil 45 cools down and the bimetallic means 43 contracts to allow the thermostat to resume its normal function.

Manual adjustment of the temperature of the mixed water in the valve outlet is controlled by adjusting the position of the thermostat 31, through the cover 40 which is in screw-threaded engagement with the casing 39 at 50. Rotation of the cover 40 axially displaces the stud 41 and said axial displacement is transferred to the thermostat via the bi-metallic means 43 and the rod 37.

As shown in Figure 3 the cross-arm member 33 defines a surface 52 which co-operates with a valve seat 51 to define a second valve opening.

The valve seat 51 is on an intermediate wall 53 of the valve housing. Therefore displacement of the theremostat 31 not only effects the valve opening 29-30 but also the valve opening 51-52.

Full opening of either of the valve openings coincides with full closure of the other valve opening and vice versa, and this-arrangement facilitates the maintenance by the thermostat of the desired temperature in the valve outlet during the hot periods.

WHAT WE CLAIM IS: 1. A heating system capable of supplying heated water to at least one supply outlet, the system comprising a heat exchanger adapted to receive cold water to be heated by the exchanger; a thermostatically controlled threeway valve connected to receive heated water from the heat exchanger at a first inlet and cold water at a second inlet, the valve having an outlet which is connected to said at least one supply outlet and is capable of receiving water from one or both inlets according to the temperature of the water in the valve outlet determined by the thermostat of the valve; and controlled means operable independently of the temperature of the water in the valve outlet to close the first inlet while the second inlet remains open to the valve outlet, whereby only water from the second inlet is directed to the supply outlet while the valve is under the control of the controlled means.

2. A system as claimed in Claim 1 in which the controlled means is time controlled whereby during one or more preselected periods of the day it acts to overrides the thermostat to maintain the first inlet closed.

3. A system as claimed in Claim 1 or Claim 2 in which the thermostat is selectively adjustable to vary the temperature in the water outlet when not under the control of the controlled means by acting to adjust the relative flows of water through the inlets.

4. A system as claimed in any one of the preceding claims in which the second inlet is progressively opened as the first inlet is progressively closed, and vice versa.

5. A system as claimed in any one of the preceding claims in which the thermostat applies a mechanical force to a valve body to open and close the first and second inlets in response to variation of the temperature of the water in the valve outlet, and wherein the controlled means is adapted to bias the thermostat and thereby the valve body to close the first inlet.

6. A system as claimed in Claim 5 in which the controlled means comprises an electrothermal motor mounted on the valve and mechanically engaged with the thermostat.

7. A system as claimed in Claim 6 in which the motor comprises a heating element capable of transferring heat to means whose overall length varies on heating to bias the thermostat and the valve body to close the first inlet.

8. A system as claimed in Claim 7 in which said means whose length varies comprises a bimetallic spring member.

9. A system as claimed in Claim 5 in which the controlled means comprises electro-magnetic means mounted on the valve and operable to mechanically bias the thermostat and valve body to close the first inlet.

10. A system as claimed in any one of the preceding claims in which the at least one supply outlet is provided in a loop conduit to direct water from the valve outlet through the loop conduit and back to the valve when the at least one supply outlet is closed.

11. A system as claimed in Claim 10 in which a pump is provided to circulate water in the loop conduit.

12. A system as claimed in any one of the preceding claims in which the heat exchanger comprises a water tank and has a primary side which is adapted to receive heating medium therethrough, and wherein the cold water is received in a secondary side of the exchanger, to be heated by the heating medium.

13. A heating system capable of supplying water to at least one supply outlet and substantially as herein described with reference to Figure 1 of the accompanying drawings.

14. A heating system capable of supplying water to at least one supply outlet substantially as herein described with reference to Figure 2 of the accompanying drawings.

15. A heating system as claimed in Claim 1 and including a valve and externally controlled means substantially as herein described with reference to Figure 3 of the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. the theremostat 31 not only effects the valve opening 29-30 but also the valve opening 51-52. Full opening of either of the valve openings coincides with full closure of the other valve opening and vice versa, and this-arrangement facilitates the maintenance by the thermostat of the desired temperature in the valve outlet during the hot periods. WHAT WE CLAIM IS:

1. A heating system capable of supplying heated water to at least one supply outlet, the system comprising a heat exchanger adapted to receive cold water to be heated by the exchanger; a thermostatically controlled threeway valve connected to receive heated water from the heat exchanger at a first inlet and cold water at a second inlet, the valve having an outlet which is connected to said at least one supply outlet and is capable of receiving water from one or both inlets according to the temperature of the water in the valve outlet determined by the thermostat of the valve; and controlled means operable independently of the temperature of the water in the valve outlet to close the first inlet while the second inlet remains open to the valve outlet, whereby only water from the second inlet is directed to the supply outlet while the valve is under the control of the controlled means.