GB1582268A

GB1582268A - Hot water installations

Info

Publication number: GB1582268A
Application number: GB28940/77A
Authority: GB
Original assignee: Chaffoteaux et Maury SAS
Current assignee: Chaffoteaux et Maury SAS
Priority date: 1976-07-12
Filing date: 1977-07-11
Publication date: 1981-01-07
Also published as: IT1080269B; ES460937A1; FR2358622A1; BE856728A; DE2729718A1; NL7706815A

Description

(54) IMPROVEMENTS IN HOT WATER INSTALLATIONS (71) We, CHAFFOTEAUX ET MAURY, a Society' Anonyme, organised and existing under the laws of the Republic of France, of 2, Rue Chaintron, 92120 Montrouge, France, 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 invention concerns installations for the production of hot water to be drawn off, essentially comprising a heat exchanger whose primary circuit is part of a closed loop comprising a driving pump and a heat generator, and whose secondary circuit, mounted in countercurrent to the first circuit, is supplied with cold water and connected downstream to a distributor of hot water.

The primary circuit of the exchanger may preferably be mounted in parallel with a central heating circuit with radiators or similar apparatus, in which case a three-way valve can allow the hot water which leaves the generator to be sent at will to this primary circuit or to the central heating circuit.

The invention relates, more particularly, among these installations, to those which are equipped with thermostatic means adapted to regulate to a predetermined value of the temperature of the hot water distributed at the outlet of the secondary circuit of the exchanger, so as to be suitable for supplying a shower or filling a bath.

In known installations, the thermostatic part generally comprises a heat-sensitive probe at least partially immersed in the stream of hot water leaving the secondary of the exchanger, just before its distribution; the (at least partial) immersion of the probe is required to obtain a minimal inertia of the thermal regulation, that is to say, a negligible response time for this regulation.

Such a solution presents the drawback of a rigid scaling of the probe and of the part of the pipe in which the latter is immersed, because the presence of the probe creates a certain turbulence in the stream of hot water in the said part.

This scaling presents the drawback of a reduction in the sensitivity of the probe and, at the limit, a constriction of the pipe concerned.

Now, we have established that, in an altogether surprising way, if the exchanger of the installation concerned is sufficiently effective, that is to say presents a big enough exchange surface and a very small inertia in the sense that it ensures a rapid transfer of calories from the primary to the secondary, especially on account of the small volume of water concerned in each instant in this transfer, the temperature of the water at the outlet of the primary of the exchanger is appreciably identical, generally near to 1 or 2 degrees Centrigrade, to the temperature of the water at the outlet of the secondary of the heat exchanger.

Accordingly, we propose an installation as defined in claim 1 below, to which reference should now be made.

The required efficiency of the heat exchanger will depend upon the particular application of the installation, and can if need be be determined by experiment.

Such an arrangement presents the great advantage of negligible scaling of the probe, seeing that the primary has circulating water running through it in a closed circuit and that the scaling due to such water is greatly reduced because of the fact that the minerals contained in this water do not recur after having once been deposited in the closed circuit.

The data provided by the probe mounted thus in the primary can be exploited in the same way as the data provided by probes in known installations.

In particular, in the advantageous situation where the driving pump is electrically supplied and where the heat generator is a gas boiler the igniting of whose burner responds to the circulation of water in the heating body, the probe can be exploited so as to automatically cut the electricity supply of the motor to the pump and thus to stop this pump and put out the burner, when the temperature of the water detected by the said probe exceeds a predetermined value, and, on the contrary, to re-establish the said supply when the said temperature again goes through the said value.

The invention will be described in more detail, by way of example, with reference to the accompanying drawing. The single figure in this drawing shows very diagrammatically an installation for the production of hot water which embodies this invention.

This installation comprises, in a way in itself known, a heat-exchanger 1 whose primary 2 (which supplies the calories) and secondary 3 (which receives the calories) are mounted so as to be run through respectively by two flows of water circulating in countercurrent.

The primary 2 is connected in a closed circuit successively to a driving pump 4 controlled by an electric motor, a heat generator 5, preferably heated by combustion of a gas, and a three-way valve 6. This valve is mounted so as to establish or cut off the communication between its first two ducts connected respectively to the output of the generator 5'and to the primary 2.

The third duct of the valve 6, to which is connected the first duct of the said valve when the communication between the first two ducts of the latter is cut off, is connected to a central heating circuit comprising radiators 7 or similar apparatus, this circuit being mounted in parallel to the primary 2.

The secondary 3 of the heat exchanger is supplied with cold water by a top pipe 8 and its bottom end is connected to a hot water distributor 9 equipped with a drawing-off tap 10.

The control of the valve 6 is coupled to that of the tap 10 in such a way that, when water is drawn off, the water heated by the generator 5 will be automatically sent into the primary 2 of the exchanger whereas, in the absence of drawing off, the said heated water is sent into the central heating circuit 7; this coupling has been schematically indicated by the chaindotted arrow 11 in the drawing.

As usual, suitable thermostatic or other means are provided selectively to neutralise the boiler 5, outside the drawing-off periods, that is to say when the valve 6 is in the position in which it establishes a communication between its first and its third duct. This is the case, for example, in summer, when no central heating is required, or else again in the season for heating when the radiators 7 are sufficiently hot.

In known installations of the kind described above, thermostatic means are provided to regulate to a predetermined value the temperature of the hot water distributed by the tap 10; this is particularly applicable when this hot water is intended to supply a shower or a bath. These means comprise a probe (schematically shown in the drawing by the chain-dotted rectangle 12) which is immersed in the stream of water coming at A from the secondary 3,just above the hot water distributor 9 and the tap 10.

As long as the temperature of the water distributed, i.e. the temperature detected by the probe 12, stays lower than a desired value to, the thermostatic regulation does not intervene.

But when the temperature of the water detected by the probe exceeds a value to, the regulation enters into play, in particular in opening an electrical interrupter mounted on the supply circuit of the pump motor. The consequent stopping of the pump results in the extinguishing of the burner of the boiler 5, which reduces the temperature of the water in the primary 2 of the exchanger and finally that of the water in the secondary 3 and distributed by the tap 10.

If the exchanger 1 is very effective, that is to say offers a large exchange surface ensuring a good transfer of calories from the primary and the secondary, and has a low inertia, that is to say a negligible response time for the transfer of the calories (because of the low volumes of water concerned in each instant in this transfer), experience has shown us that, in an entirely unexpected way, the temperature of the water at the outlet B of the primary 2 is practically the same, 2"C away at the most, as the temperature of the water at the outlet A of the secondary 3.

The heat exchanger 1 is of the type comprising baffles, in conformance with our British Patents Nos 1,430,491, and 1,494,060 which describe an exchanger in which the superposed baffles form a succession of levels or compartments forming part alternatively of the primary and the secondary of the exchanger and which offer considerable efficiency and a low inertia. Reference should be made to the said British Patents for further details of the exchanger construction.With a boiler 5 of 22 therms, the temperatures of the water respectively at points A (outlet of the secondary corresponding to the drawing-off), B (outlet of the primary), and C (inlet of the primary) are, for drawn-off deliveries of hot water rising from 180 to 440 litres an hour, given by the following table: Delivery (I/h) A(OC) B( C) C( C) 180 63 62 75 260 62 62 82 360 60 61 85 440 58 60 86 This is why, in conformance with this invention, the probe of the thermostatic regulation device is immersed at the outlet B of the primary, the probe having been schematic ally indicated by the rectangle 13 in the drawing.

This regulation can control the supply of the electric motor of the pump 4, as indicated by the chain-dotted arrow 14.

The said regulation could, alternatively, be conceived in an entirely different suitable way, putting into operation, continuously or on an all-or-nothing basis, any of the other parts capable of acting, directly or indirectly, on the temperature of the water circulating in the primary 2.

In this way, one could envisage constructing the three-way valve 6 in such a way that it shares the deliveries of hot water admitted to its first duct between its second and third ducts as a function of the position of its control means, this position being then controlled by the thermostatic signals relayed by the probe.

One could alternatively envisage the direct action of the probe on a part suitable for controlling the admission of gas to the burner of the boiler 5.

As has been said above, the fact of the immersion of the probe in the primary circuit and not in the secondary circuit of the exchanger 1 offers the important advantage of considerably reducing the risks of the scaling of this probe by the flow of water in which it is immersed.

The above table shows that, if one wishes to draw off at the tap 10 water at a tempera ture of the order of 60"C - that the ther- mal regulation be controlled by the temperature at the outlet of the primary 2 or by the temperature at the outlet of the secondary 3 the temperature at the inlet C of the primary is all the higher when the delivery of the drawnoff hot water is itself increased; as this temperature at C is near the temperature at the outlet of the boiler 5, the latter stays practically permanently lit for the maximal deliveries drawn off whereas, for lower deliveries, it stays extinguished for relatively long periods, extending for example for a fifth of the total duration of drawing off.

Following from which and whatever the mode of realisation adopted, one finally has at one's disposal an installation for producing hot water whose composition and functioning result sufficiently from the foregoing.

This installation, as pointed out above, offers the important advantage over known arrangements with regard to the useful absence of scaling of the immersed probe used to ensure thermostatic regulation.

We have moreover established that the illustrated arrangement (with immersion of the probe in the outlet of the primary of the exchanger and no longer in the outlet of the secondary) offers the following other unexpected advantage.

The feedback loop of the thermostatic regulation is much shorter in such an arrangement than in previous arrangements; indeed, the controller element (primary 2) and the controlled element (pump and boiler 5) of the regulation are placed in a same closed circuit so that the regulator effect generated by the controlled element at the time of a regulation very rapidly has an effect on the controller element and conversely, and the "response" of the regulation is consequently very rapid. On the contrary, in previously known arrangements, where the controlled element is the same as before (pump and boiler), but where the controller element is the secondary 3 of the exchanger lithe feedback loop comprises the said exchanger in addition to the closed circuit above, which adds the thermal inertia of the exchanger to the inertia of the regulation.

The sort of gain effected to the response time of the regulation more than compensates for the slight defect pointed out above concerning the control temperature to which this regulation is slaved.

It will be appreciated that many modifications can be made to the arrangement illustrated.

WHAT WE CLAIM IS: 1. An installation for the production of hot water for drawing off, comprising a heat exchanger whose primary circuit is part of a closed loop comprising a driving pump and a heat generator, and whose secondary circuit, mounted in countercurrent to the primary circuit, is supplied with cold water and connected downstream to a distributor of hot water, and thermostatic means adapted to regulate to a predetermined value the temperature of the hot water distributed at the outlet of the secondary circuit of the exchanger and comprising an immersed probe at the outlet of the primary of the exchanger, wherein the heat exchanger is a high efficiency exchanger constituted by baffles defining between them a succession of superposed compartments forming part alternatively of the primary and of the secondary of the exchanger.

2. An installation according to claim 1, wherein the primary circuit of the exchanger is mounted in parallel with a central heating circuit, a three-way valve controlled by the water drawing-off tap allowing the hot water which comes from the generator to be sent selectively to the primary circuit or to the central heating circuit.

3. An installation according to claim 1 or 2, in which the thermostatic means of the probe are connected to operate the driving pump.

4. An installation for the production of hot water for drawing off, substantially as herein described with reference to the accompanying drawings.

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. its first duct between its second and third ducts as a function of the position of its control means, this position being then controlled by the thermostatic signals relayed by the probe. One could alternatively envisage the direct action of the probe on a part suitable for controlling the admission of gas to the burner of the boiler 5. As has been said above, the fact of the immersion of the probe in the primary circuit and not in the secondary circuit of the exchanger 1 offers the important advantage of considerably reducing the risks of the scaling of this probe by the flow of water in which it is immersed. The above table shows that, if one wishes to draw off at the tap 10 water at a tempera ture of the order of 60"C - that the ther- mal regulation be controlled by the temperature at the outlet of the primary 2 or by the temperature at the outlet of the secondary 3 the temperature at the inlet C of the primary is all the higher when the delivery of the drawnoff hot water is itself increased; as this temperature at C is near the temperature at the outlet of the boiler 5, the latter stays practically permanently lit for the maximal deliveries drawn off whereas, for lower deliveries, it stays extinguished for relatively long periods, extending for example for a fifth of the total duration of drawing off. Following from which and whatever the mode of realisation adopted, one finally has at one's disposal an installation for producing hot water whose composition and functioning result sufficiently from the foregoing. This installation, as pointed out above, offers the important advantage over known arrangements with regard to the useful absence of scaling of the immersed probe used to ensure thermostatic regulation. We have moreover established that the illustrated arrangement (with immersion of the probe in the outlet of the primary of the exchanger and no longer in the outlet of the secondary) offers the following other unexpected advantage. The feedback loop of the thermostatic regulation is much shorter in such an arrangement than in previous arrangements; indeed, the controller element (primary 2) and the controlled element (pump and boiler 5) of the regulation are placed in a same closed circuit so that the regulator effect generated by the controlled element at the time of a regulation very rapidly has an effect on the controller element and conversely, and the "response" of the regulation is consequently very rapid. On the contrary, in previously known arrangements, where the controlled element is the same as before (pump and boiler), but where the controller element is the secondary 3 of the exchanger lithe feedback loop comprises the said exchanger in addition to the closed circuit above, which adds the thermal inertia of the exchanger to the inertia of the regulation. The sort of gain effected to the response time of the regulation more than compensates for the slight defect pointed out above concerning the control temperature to which this regulation is slaved. It will be appreciated that many modifications can be made to the arrangement illustrated. WHAT WE CLAIM IS:

1. An installation for the production of hot water for drawing off, comprising a heat exchanger whose primary circuit is part of a closed loop comprising a driving pump and a heat generator, and whose secondary circuit, mounted in countercurrent to the primary circuit, is supplied with cold water and connected downstream to a distributor of hot water, and thermostatic means adapted to regulate to a predetermined value the temperature of the hot water distributed at the outlet of the secondary circuit of the exchanger and comprising an immersed probe at the outlet of the primary of the exchanger, wherein the heat exchanger is a high efficiency exchanger constituted by baffles defining between them a succession of superposed compartments forming part alternatively of the primary and of the secondary of the exchanger.