FR2786853A1 - Water heater for bathroom use, comprises a drilled chimney assembly enabling water regeneration - Google Patents

Abstract

The hot water production device comprises a casing (20) for a heating element (18) and a chimney (24) mounted on a pipe (26) extending between a top and bottom end. The pipe is drilled near its bottom end with a first and second holes (42,44) allowing water exchanges between the inside and outside of the chimney. The pipe has diaphragms (28,30,32) for limiting the water flow in the pipe and to cause pressure loss in it.

Description

i The invention relates to the field of water production devices

domestic hot water.

  Domestic hot water production is currently based on the concept of a storage tank taking advantage of the tariff options offered by electricity producers. The water is heated in the tank during attractive tariff periods (night periods for the most part) to thus constitute a reserve of hot water which will be drawn

  1o gradually during the day.

  However, it may be necessary to reheat

  partial during the day, when a lot of hot water is drawn off.

  There are already known devices for producing domestic hot water, intended to allow partial reheating, consisting of a balloon for containing water to be heated, a heating element, a heating element casing surmounted by '' a chimney fitted with orifices and a thermostatic valve. The tank is provided in its lower part with a cold water inlet and a hot water outlet. A pipe extends from the hot water outlet to the top of the tank so as to allow hot water to be drawn off from the top of the tank. The heating element is an electrical resistance. The heating element housing constitutes a reservoir in the volume of which the heating element heats the water. The casing is provided, on its lower part with cold water inlets, and on its upper part, with a hot water outlet. This hot water outlet communicates directly with the chimney. The chimney is vertical. Its lower end communicates with the hot water outlet of the

  casing. Its upper end is located at the upper part of the balloon.

  The openings are located near the lower end of the chimney. The thermostatic valve is located between the holes and the upper end of the

fireplace.

  In this type of device, when the water is heated, its density decreases. Therefore, under the effect of Archimedes' push, hot water tends to rise above cooler water, whose density is higher. The chimney directly conducts the hot water produced in the casing, in the upper part of the tank, limiting the stirring phenomena

  In this one. The chimney constitutes what is called a thermosiphon.

  If hot water is drawn from the tank, cold water enters through the cold water inlet; the heating element is put into operation. The hot water produced in the casing rises through the chimney where it is mixed with the cold water entering through the orifices. As hot water is produced and exits from the top of the chimney, the layer of hot water occupies an increasing volume, above the layer of cold water and the interface hot / cold water goes down to the bottom of the tank. The hot water then forms a more or less homogeneous layer on top of the cold water. The temperature variation between the layer of hot water and that of cold water has a more or less abrupt profile. The larger the layer of hot water, the smaller the pressure difference between the upper and lower ends of the chimney. The flow in the chimney therefore also decreases. The arrival of cold water through the orifices then becomes less important and the temperature of the water in the chimney increases. At a given temperature of hot water at the thermostatic valve, this closes the chimney flue. The chimney is closed by the thermostatic valve approximately when the hot water / cold water interface reaches approximately one fifth of the height of the tank. Up to this level, the layers of hot and cold water are generally stratified. When the thermostatic valve closes

  the chimney, hot water can no longer rise in the chimney.

  However, the flow rate at the outlet of the housing does not cancel out as long as there is a temperature difference between the water in the housing and the water around the housing. So even if the water heats up in the crankcase enough for a thermostat in the crankcase to shut off the heating, the hot water produced in the crankcase continues to flow through the ports. This generates a stirring of the water, as in flasks devoid of thermosiphons, the water leaving the flask during a new racking is then barely lukewarm. These partial heating hot water production devices are therefore not entirely satisfactory. In addition, the presence of the thermostatic valve requires the resolution of many important problems, among which the control of its reliability, its scaling (which can eventually lead to its ineffectiveness), or its cost (reaching 40% of the total cost of the chimney ). These difficulties are

  lo considered as unacceptable by industrialists.

  An object of the invention is to provide a chimney for a device for producing hot water allowing the reconstitution in hot water, of part or all of the volume of such a device, this volume corresponding to the desired quantity, without destroying the stratification

hot / cold water.

  With a view to achieving this aim, according to the invention, a chimney for a device for producing domestic hot water is provided, comprising a heating element casing surmounted by a duct extending between a high end and a lower end, this duct being pierced near the lower end, with a first orifice to allow water to be exchanged between the inside and the outside of the chimney, characterized in that the duct is pierced, between the first orifice and the upper end, a second orifice to allow exchanges of water between the interior and

the outside of the fireplace.

  Indeed, the presence of the first and second orifices determines two sections in the chimney. A first section is located between the first and second ports and a second section is located between the

  second orifice and the upper end of the chimney.

  During a first phase, the hot water heated in the casing is partially cooled by the cold water drawn in at the first and second orifices. The mixture obtained is carried out directly in part

high of the device.

  In a second phase, the effect of the decrease in the pressure difference at the ends of the second section, when the volume of the layer of hot water in the upper part of the device increases, leads to

  a decrease in flow in the second section of the chimney.

  This occurs approximately when the hot water / cold water interface has descended to the level of the second port. Part of the total volume of the device was thus reconstituted in hot water. But o unlike the prior art device described above, thanks to the presence of the second orifice, the hot water contained in the casing before the thermostat triggers the stopping of the heating and just after it has been triggered, can flow through the second orifice in the hot layer and not in the cold layer. There is therefore an inversion of the direction of flow through the second orifice. But, brewing is avoided and the

  hot / cold water stratification is preserved.

  Advantageously, the chimney according to the present invention is provided with means for guiding the water passing through at least one of the first and second orifices, along the external face of the duct, in the direction of the upper end. This advantageous variant of the invention promotes the fall of the flow in the second section of the chimney. These means further limit the mixing of hot and cold water. The assembly constituted by the second orifice and these

  means, forms a kind of hydraulic valve.

  Advantageously, the means for guiding the water passing through at least one of the first and second orifices, along the external face of the duct, in the direction of the upper end, comprise a flange, surrounding this duct, leaving a space between this duct and the internal face of the flange, extending towards the upper end of the chimney and hermetically joined to the external face of the duct, under the

first or second port.

  Advantageously also, the chimney according to the invention comprises a duct provided with diaphragms to limit the flow of water in the

  leads and generate pressure losses therein.

  Advantageously, the collar hermetically joined to the external face of the duct, under the second orifice, extends over approximately a quarter to half of the total length of the chimney. Advantageously, the collar, hermetically joined to the external face of the conduit, under the first orifice, is shorter than the collar lo hermetically joined to the external face of the conduit under the second orifice, and preferably has a length less than a quarter of the

total length of the chimney.

  According to another aspect, the invention is a device comprising a

  chimney such as that described above.

  The invention allows the reconstitution of any quantity of hot water in the event of an occasional shortage, but can also favor the emergence or development of other types of devices for producing hot water. Indeed, since the stratification is never destroyed by a partial heating of the enclosure water, it becomes for example possible to use energy sources which are only available intermittently (heating by solar energy, heating by a heat pump when it is not used for heating buildings, etc.). The chimney according to the invention can also lead, thanks to better management of the heating periods, to a reduction in the storage volume. Thus, with services rendered equivalent, this leads to a reduction in the size of the device, therefore also in its production cost and its heat losses. We can also consider the development of a semi-instantaneous heating device with moderate electrical power (the production of domestic hot water can then be relocated and be located as close as possible to the draw-off points, which leads

  among other things to eliminate online heat losses).

  Other aspects, aims and advantages of the invention will become apparent on

  reading of the detailed description which follows. The invention will also be better

  understood with reference to the drawings in which: - Figure 1 schematically shows in section a particular but non-limiting embodiment of a device according to the invention; - Figure 2 is an explanatory diagram of the operating principle of the invention on a device simplified compared to that shown in Figure 1; - Figure 3 shows schematically the device shown in Figure 1, during a first operating phase; - Figure 4 schematically shows the device shown in Figure 2, during a second operating phase; - Figure 5 shows schematically the device shown in Figure 2, during a third operating phase; and - Figure 6 shows an example of a temperature profile in the

  casing of a device according to the present invention.

  A particular, but not limiting, embodiment of the device 1 for producing hot water according to the present invention is

shown in Figure 1.

  This device 1 comprises an enclosure 2 for containing the water to be heated.

  This enclosure 2 is generally cylindrical of revolution.

  The enclosure 2 is placed so that its axis of revolution is vertical. It has a lower wall 8 and an upper wall 10

  generally perpendicular to the axis of revolution of the enclosure 2.

  The bottom wall 8 is provided with a cold water inlet 12, a

  hot water outlet 14 and a drain 16.

  The cold water inlet 12 makes it possible to fill the enclosure 2 with cold water.

  The hot water outlet 14 makes it possible to draw hot water from the enclosure 3o 2. This hot water outlet consists of a vertical pipe 17

  extending from the bottom wall 8, almost to the top wall 10.

  Thus, hot water is drawn near the top of enclosure 2.

  Conversely, the cold water inlet 12 introduces cold water into

  enclosure 2, near the bottom thereof.

  A heating element 18 is placed inside the enclosure 2, near the bottom of the latter. Preferably, this heating element 18

is an electrical resistance.

  The heating element 18 is surmounted by a chimney 24 to guide the hot water at the top of the enclosure 2. The chimney 24 comprises a casing

20 and a conduit 26.

  The heating element 18 is surrounded by the casing 20. The casing 20 preferably has the shape of a cylinder whose axis of revolution is

  collinear with that of enclosure 2.

  The cylinder of the housing 20 is closed at its upper end with a housing wall 22. This housing wall 22 is perpendicular to the axis of revolution of the housing 20. The lower end of the housing 20 is open to the rest of enclosure 2 so as to allow cold water to enter

the housing 20.

  The casing wall 22 is pierced in its center with a hole surmounted by the duct 26. This duct 26 has approximately the shape of a cylinder whose

  the axis of revolution is collinear with that of enclosure 2.

  The duct 26 extends from the casing wall 22 to near the

  upper wall 10 of enclosure 2.

  The conduit 26 includes a first 28, a second 30 and a third 32 diaphragms to limit the flow of water in the conduit

  26 and generate pressure losses therein.

  The conduit 26 is pierced with first (s) 42 and second (s) 44 orifices

  located just above the first 28 and second 30 diaphragms.

  The first diaphragm 28 is located at the casing wall 22, between the casing 20 and the duct 26, that is to say at the bottom end of the duct 26. The second diaphragm 30 is located approximately at the level of the top of the first lower third of the conduit 26, downstream of the first orifices 42 and upstream of the second orifices 44, with reference to a flow of water in the chimney 24 from bottom to top, The third diaphragm 32 is located approximately at the top of the second third of the height of the conduit 26, above the first

  28 and second 30 diaphragms, downstream of the second orifices 44.

  The internal diameter of the first 28, second 30 and third 32

  diaphragms is less than that of conduit 26.

  The first diaphragm 28 generates a pressure drop in the water flow, in the chimney 24, when the water circulates from bottom to

  high, between the casing 20 and the duct 26.

  The second diaphragm 30 generates a pressure drop in the water flow, in the chimney 24, when the water circulates from bottom to top, between the first lower third of the conduit 26 and the third that is there

immediately superior.

  The third diaphragm 32 generates a pressure drop in the water flow, in the chimney 24, when the water circulates from bottom to top, between the lower two thirds of the conduit 26 and the upper third of the

conduit 26.

  The diameter and / or the number of first (s) 42 and second (s) 44 orifices is (are) chosen (s) sufficiently large (s) so that the pressure losses induced at their level are negligible compared to those due to the different diaphragms 28, 30, 32. Thus, for the example set out here, the first 42 and the second 44 orifices are respectively the number of

  three and are distributed around the perimeter of conduit 26.

  The position of the first 42 and second 44 orifices makes it possible to define a first 38 and a second 40 sections, on the chimney 24. The

  first section 38 is located between the first 42 and second 44 orifices.

  The second section 40 is located between the second orifices 44 and

  the high end of the chimney 24.

  The first 28 and second 30 diaphragms are each

  respectively topped by a cylinder 4 or 6.

  The cylinders 4 and 6 have an external diameter less than the internal diameter of the conduit 26. These cylinders 4 and 6 have their axis of revolution collinear with that of the conduit 26, each cylinder 4 or 6 is hermetically connected to one of its axial ends , respectively at the first 28 or at the second 30 diaphragm, so that the opening of each diaphragm opens into the interior of a cylinder 4 or 6. These cylinders 4 and 6 have a length such that the projection on the lo conduit 6, from their axial end not linked to a diaphragm, is located

  respectively above the first 42 and second 44 orifices.

  The cylinders 4 and 6 prevent water from passing through the first 42 or second 44 orifices, during the priming phase, that is to say

  during the initial water heating phase.

  The conduit 26 is also provided with a first 34 and a second

36 collars.

  The first 34 and second 36 flanges surround the duct 26, leaving a space between this duct 26 and the internal face of the first 24 and second 36 flanges, and extend respectively from the first 2o 42 and second orifices 44 in the direction of the high end of the chimney 24. The first 34 and second 36 flanges are attached to their base to the duct 26. They are hermetically welded to the external face of the duct 26 under the first 42 and second 44 orifices respectively. The first flange 34 stops, towards the top of

  the chimney 24, below the second diaphragm 40.

  The configuration with a first 34 and a second 36 flanges and cylinders 4 and 6 respectively above the first 28

  and second 30 diaphragms, leads to an optimization of the results.

  According to other embodiments, the first 34 and second 36 flanges can be replaced, for example, by pipes hermetically welded by one of their ends to the external wall of the duct 26, each pipe communicating with a first 42 or a second 44

  orifice by its end welded to the duct 26.

  We will describe below the operating principle of the

present invention.

  Reference is made below to FIGS. 2 to 6 to describe this principle. The device used here to describe the operating principle of the invention is in accordance with the present invention but does not exactly correspond to the device described above. In particular, it does not have the first flange 34. This simplifies, for better

  understanding, description of the operating principle of the invention.

  If the pressure losses induced at the first 42 and second orifices 44 are negligible compared to those due to the first 28, second 30 and third 32 diaphragms, the mass flow rates at the outlet is of the casing 20, at the outlet of the first section 38 and at the end of the second section 40 (respectively icarter, ", hnc ', rhc 2) depend only on the weights of the water columns located in the section immediately below: m = | r2Pcart r pcart1rIrúDT ADc; ar (1) cart, , \ 1 óF, 4. ca ,, o I ó--, carfcr 4 éCarfgr 2O with: AP,., = J (p, -pcar ,,,,) gdz or h 2ptronc-, nc-1 Ir D: cc (2) \ t> troncI \ 't tro4nc I with: APro ,,, l = ,,, ó- Ptronc_ l) gd: before inversion zo, o = JIpr_0' "-Ptron_1) gd after inversion 1: 1 2 PIrc 2 Aertc _, 2 _ I o nc2 (3) iiirnc-- 2 4 _: "" "nc 23 with: = ,,, = - p <M ,,,) d. 2 before inversion" 1 with: AP ,,,, 2 = - P., 2) gdz after inversion O: 2 o: APcarter, APironc 1 ApI ,,, ronc 2 represent the pressure differences between the top and the bottom, re spectrally from the casing 20, the first section 38 and the second section 40, that is to say the driving pressure in these various elements; - Pcarter, P, p pronc ,,, - and poc2 are respectively the densities of water in the casing, in the enclosure 2 outside the chimney 24, in the first section 38 and in the second section 40; - Dchem is the diameter of the chimney 24; - Zor (er ,, tronc1 and:, 2 are the pressure drop coefficients, respectively at the level of the first 28, second 30 and third 32 diaphragms; and - Zo, z1, z2 and z3 are the respective dimensions of the first orifices 42 , second orifices 44, from the top of the second flange 36 and from the top of the

  chimney 24, taking the lower wall 8 as a zero dimension.

  During a first phase corresponding to FIG. 3, the cold water entering the casing 20 with a flow rate, aside, is heated by the heating element 18 and leaves at a temperature Tct.r. This flow rate and therefore the outlet temperature remain practically constant as long as the layer of hot water does not reach the zero level. The fluid leaving the casing 20 is then mixed with the cold water entering through the first orifices 42 (dimension zO) and circulates in the first section 38 at a temperature Tû. 1. It is again cooled at the level of the second orifices 44 (dimension z.) and reaches the upper part of the flask at a temperature T'tc 2. Hot water and water

  cold in the enclosure 2 are separated by a stratification layer 50.

  As the stratification layer 50 progresses, the driving pressure AP ,,, 2 at the second section 40 decreases, leading to a decrease in the flow ironc 2 and to an increase in the temperature t ,,, , 2. The other parameters of enclosure 2 do not vary during this first phase of operation. This evolution persists

until Ttnc- 1 = Ttronc-2.

  Then, the flow M ,,,, c 2 reaches the value belgium ,, then the flow at the second orifices 44 is reversed. Then begins a second phase

(figure 4).

  The drop in driving pressure AP ,, 2 results in a very large reduction in the flow rate in the second section 44, preventing hot water

  continue to feed the top of the balloon directly.

  You can also choose the pressure drop coefficients so that the inversion takes place when the layer of hot water reaches the top of the

second flange 36 (z2).

  This second flange 36 has a triple role: to inhibit hot water leaks until inversion (this function is also improved by the use of cylinders 4 and 6); causing the driving pressure APl ,,, _ 2 to drop suddenly at the time of the reversal at the second section 40 and correspondingly increasing the driving pressure for the first section 38, by replacing the water in the second flange 36, until then cold with hot water; and allow the preservation of the stratification layer by directly taking the fluid leaving through the second orifices 44 to the

level of the hot water layer.

  During the second phase (FIG. 4), the driving pressure AP, o ,, c -l in turn gradually decreases, due to the progression of the stratification layer 50 towards the bottom of the enclosure 2. This

  evolution continues until the temperatures Ttr ,,, on and Tcrter are equalized.

  This equalization of the temperatures leads to an equalization of the flow rates rthronc and h trunk _2 and to an inversion of the flow at the level of the first orifices 42. Then begins a third phase (FIG. 5). We can estimate the flows circulating in the first 38 and second

  sections from relations (1) to (3).

  Thus, if it is desired that the flow circulating in the second section 40 decrease very sharply after the inversion has taken place at the level of the 1o second orifices 44, the associated driving pressure, APtronc 2, must be canceled. Note that after the inversion, at the second orifices 44, the length of the first section 38 is increased by the height of the second flange 36, that of the second section 40 thereby being reduced. Effective lengths and effective length ratios can be calculated. The corrected dimensions zl ,, net z2 _ ,,,, take this phenomenon into account. On the other hand, before inversion, the first 38 and

  second 40 sections are well separated by the second orifices 44.

  The lower the pressure variation between the start of heating and the 2nd time of the inversion, the fewer the mixing phenomena. Thus, over short lengths of sections, the increase in water temperatures at the outlet of the chimney 24 is low and the stratification layer has not had time to degenerate. This result is obtained

  by not having the second orifices 44 too low.

  Typically, this pressure evolution behavior is obtained when the ratio of the length of the second 40 to that of the first 38 sections is between 1 and 4 and preferably equal to two or three. That is to say when the second orifices 44 are drilled at a third of the height of the chimney 24 (which gives a ratio 3 o of the length of the second section 40 to that of the first section 38 equal to 2) and in adding a second flange 36 whose height is one third that of the chimney 24 (which leads after the inversion to

  level of the second orifices at an effective ratio of 1/2).

  Let us carry out an example of dimensioning calculation, it being understood that for another size of balloon, the calculation will have to be redone according to a

  methodology similar to that used below.

  Let us first calculate the ratios of coefficients of

load losses.

  On inversion we have the following relationships: - at the level of the first orifices 42: mcarter = fhir.,: _ I Tcorter = Ttronc 1 Pcartor = Ptronc 1 and: ntroncI p _ I "_ v - z0 ó, carer APcrter 0 , 44zo The coefficient 0.44 comes from the shape of the temperature profile in the housing 20 (fig. 6) and depends very little on the temperatures of the incoming water

and outlet from the housing 20.

  - at the second orifices 44: thro- Ic = filtrnc, 2 Ttrvnc1 = Ttronc_2 Ptnc_ = Pronc 2 and: tronc2 ranc 2t Z3 Inv- Z trunk1) ronc l Z i-ZO The absolute and relative values of the pressure drops are then chosen by setting the following additional constraints: A t = Os:

  The temperature at the outlet of the casing 20 must be 60 C.

  The temperature in the first section 38 must be close to the

  crankcase temperature 20. Let's choose it equal to 58 C.

  The temperature at the outlet of the chimney 24 must be 52 C.

  Before the inversion, the layer of hot water gradually increases. When the hot water / cold water interface reaches the upper part of the second flange 36, there is an inversion of the flow of

  water at the second orifices 44.

  After this inversion, the outlet temperature at the second orifices 44 is close to 52 C. With regard to the inversion at the first orifices 42, there is no particular constraint, except that '' it must take place after

  that at the level of the second orifices 44.

  Let us calculate the care pressure drop coefficient ,,, at the level of

lo first diaphragm 28. If the heating power of the resistor is W = 2900 W, and if

  suppose that the cold temperature Tf ,, d is 16 C and that the outlet temperature of casing Tco ,, or must be 60 C, we must have: casing = 0,0158kg / s -CPAT o Cp is the specific heat constant pressure water and

I T = Tcrter, - Ttfold.

  The driving pressure at the casing 20 is then calculated using the profile proposed in FIG. 6: 2 0 cartIfer T (P cold P- cartridges) gdz = 1 5.3 Pa o

  O pftid is the mass density of water at temperature Tfoid.

  To obtain a flow rate equal to that calculated above (0.0158 kg / s), with a value of the driving pressure of 15.3 Pa, it is necessary to impose pressure drops at the outlet of the casing 20 equal to: 2 5 Xatr2Pcarter = 190 -Pcarer = ecarercrrir 1D2chantt 4h Let us calculate the coefficient of pressure losses at the level of the second

diaphragm 30.

  A temperature in the first section 38 equal to 48 C imposes the flow rate in this first section 38 titr ,, calculated from the equalities: s nicaHrTca ,,, r + nto "f - I Tfr ,, J = fl <, f7 It -] and i, ri-rvnc, thcartfr

  O t, 'h, is the mass flow rate at the level of the first orifices 42.

  Which gives the following value for the flow ui: ,,, _ t.carter (Tcarter -Tfrod) - 'mtroncl = = 0,0166kg / s filron, 1' Trunk I - Tfrod So if the driving pressure at this same first section 38 is worth:: 1 f = f (1,) gdz = 48.3Pa zo the coefficient of pressure losses ,,, -onc, must be fixed at: ronc12AftronC_ 1 = 545 P '"'" c- 1 Likewise calculate the pressure drop coefficient Iron, _2 at

level of the third diaphragm 32.

  An outlet temperature of 52 C in the upper part of the enclosure requires a rhronc_2 flow of: mcarter (Tcarter - Tfrofd) 0193kgs thtonc trunk, 0193kg / sfd So if the driving pressure at the terminals of section 2 rises to (before inversion ): A6tro ,, c2 J (PJ o, -Pte ,, 2) gd1 = 77,71> a the pressure drop coefficient ,,,, must be set to: tro ,, c 2 2AP tic2 = 650 Pronc 2 p, _D 2 Thus, the ratio of the pressure drop coefficients., 2 / óro, _ is of the order of 1 (= 1.19); The inversion therefore takes place when the hot water layer reaches a dimension z3 inv such that: Z3 _ inv-Z1 trunk 21 3 if-- = - - 1.19 Zl - Zo ótronc 1 The inversion takes place for this value of the ratio of the driving pressures P ,, oc 2 / AP ,, nc_, when the length ratio section 2 / section 1 is

approximately equal to 2 or 3.

  Note also that the height of the collar can be

  slightly increased so that its upper part reaches z3 inv.

  After inversion at the second orifices 44, the cold water from

  the second flange 36 is replaced by water at temperature Tte ,,, -.

  To the initial driving thrust APoc, there is therefore added an additional thrust due to the water height in the second flange 36. The new flow rhtroncl and the new temperature Tt ,, nc, of equilibrium which result therefrom satisfy the relationships = mcarir (Tcaor - nd) ltO, 'o = 7ó -T itnbpl = -i tic1 Ir 1; P ",,, cl - Tú," ,,,, Z 4' rc = f.:)gdz = jd -. - Zo) It comes: T, .o.cl 5 I C htroncl 0,02kg / s Apttrc, l; 72Pa The behavior thus obtained is completely satisfactory. The flow rate in the first section r ,, and the driving pressure A / fTC_ in this same section then decrease as the stratification layer 50 progresses, while the temperature in the first section 38 T ,, s raise until the reversal point of the first 1: 5 holes 42 is reached. We then have: htlronc I = mtronc 2 Ttronc, = Trtonc 2 t ,,. - _ inv - Zo _ 2.87 z '_ ,, z_ 1.26 2.87 or: ócarnr 0.44z0 z0 As an example, we find below dimensions that

  meet the conditions defined and calculated above.

  zo = 0.225m z. = 0.558m z2 = 0.891m z3 = 1.225m Height of the second flange 36 = 0.333 m Diameter of the chimney 24 = 40 mm

Claims (8)

  1. Chimney (24) for producing domestic hot water comprising a casing (20) of heating element (18) surmounted by a duct (26) extending between a high end and a low end, this duct (26) being pierced near the lower end, with a first orifice (42) to allow exchanges of water between the inside and outside o10 of the chimney, characterized in that the duct (26 ) is pierced, between the first orifice (42) and the upper end, with a second orifice (44) to allow exchanges of water between the interior and the exterior of the chimney (24). 2. Chimney according to claim 1, characterized in that the duct (26) is provided with diaphragms (28, 30, 32) to limit the flow   water in the conduit (26) and generate pressure losses in the latter   this. 3. Chimney according to claim 2, characterized in that the duct (26) has a first diaphragm (42) at its lower end, that is to say, at the level of the communication between the casing (20 ) and the conduit (26), a second diaphragm (30), downstream of the first orifice (42) and upstream of the second orifice (44), with reference to a flow of water in the chimney (24) from below at the top, and a third   diaphragm (32) downstream of the second orifice (44).   4. Chimney according to claim 3 is characterized in that   that it is provided with at least one cylinder (4, 6) surmounting the first (42) or the second (44) diaphragm.   Fireplace according to one of the preceding claims,   characterized in that the chimney (24) comprises a first section (38) between the first (42) and second (44) orifices and a second section   (40) between the second orifice (44) and the upper end of the chimney (24).   6. Chimney according to claim 5, characterized in that the ratio of the length of the second section (40) to that of the first section (38) is between 1 and 4 and preferably approximately equal to 2.   7. Chimney according to one of the preceding claims,   characterized in that it is provided with means for guiding the water passing through at least one of the first (42) and second (44) orifices, the   along the outer face of the conduit (26), towards the upper end.   8. Chimney according to claim 7, characterized in that the l0 means for guiding the water passing through at least one of the first (42) and second orifice (44) orifices, along the external face of the conduit (26 ) towards the upper end, comprise a flange (34, 36), surrounding the duct (26) leaving a space between this duct (26) and the internal face of the flange (34, 36), extending towards the upper end of the chimney (24), and hermetically sealed to the external face of the   conduit (26), under the first (42) or the second orifice (44).   9. Chimney according to claim 8, characterized in that the collar (36) hermetically joined to the external face of the duct (26), under the second orifice (44), extends over approximately a quarter to the   half the total length of the chimney (24).   10. Chimney according to one of claims 8 and 9 characterized by   the fact that the collar (34), hermetically joined to the external face of the conduit (26), under the first orifice (42), is shorter than the collar (36) hermetically joined to the external face of the conduit (26) under the second orifice (44), and is preferably less than a quarter of the   total length of the chimney (24).   11. Device for producing sanitary hot water characterized in that it comprises a chimney comprising a casing (20) of heating element (18) surmounted by a conduit (26) extending between an upper end and a lower end, this duct (26) being pierced near the lower end, with a first orifice (42) to allow exchanges of water between the interior and the exterior of the chimney, and that the duct ( 26) is pierced, between the first orifice (42) and the upper end, with a second orifice (44) to allow exchanges of water between the interior and the exterior from the chimney (24).