Patent Grant
9134037
The present application is a national phase entry under 35 U.S.C. §371 of the International Application No. PCT/EP2009/052401, filed on Feb. 27, 2009, published in French, which claims the benefit of French Patent Application No. 0851465, filed on Mar. 6, 2008, the entire disclosures of which applications are hereby incorporated herein by reference.
The present invention relates to an installation for producing sanitary hot water.
Traditionally, an installation for producing sanitary hot water, with which a dwelling is equipped, both an individual and collective one, comprises a boiler and two exchangers, one of which will be called a primary exchanger and the other one a secondary exchanger.
The boiler which for example operates with gas or fuel oil is used for heating a first liquid.
Advantageously, in the case of a so-called mixed installation, this may be water circulating in the radiators of a central heating system.
For this purpose, the boiler is equipped with the primary exchanger, which has the function of transmitting a portion of the heat generated by the burning gases from the combustion of the burner with which the boiler is equipped.
This boiler is for example of the condensation type, comprising helicoidal tubular coil(s), for example in steel, surrounding the burner and in which passes the first liquid to be heated.
Exchangers of this kind are for example described in patent documents EP-0678186 B1, WO 2004/036121 A1 and FR-A-2896856.
The first liquid, which circulates in a closed circuit, may be selected and/or treated, notably demineralized and degassed so that it does not pose any problems related to corrosion and to deposit of solid materials, notably of limestone—a source of clogging—, against the walls of the tube(s) of the primary exchanger.
These potential problems essentially result from the very high level of the applied temperatures.
In this respect, and as a simple indication, the burnt gases from the burner for example have a temperature of the order of 950° C. and the first liquid, initially at room temperature, is heated to a temperature of the order of 80° C.
The secondary exchanger has the function of transmitting heat from the first thereby heated liquid to the second liquid, in this case sanitary water, which is drawn with the purpose of supplying on demand a point of use such as a sink, a washbasin, a shower, and/or a bathtub for example.
The sanitary hot water is stored in a heat-insulated walled enclosure, usually called a “tank”.
A secondary exchanger of this kind is for example described in patent document FR-A-2847972.
In the secondary heat exchanger, the applied temperatures are considerably lower than those in the primary exchanger so that the passage inside this exchanger of sanitary water not treated beforehand—i.e. drinking water from the public water mains—does not in principle pose any critical problem of corrosion or of deposits of solid materials.
It seems to be established that so-called “hard” water, i.e. having a high lime content, is without any danger for the consumer (even if the latter is a great water drinker); however it poses serious problems of scale in conduits at a higher temperature, of the order of 60° C. to about 65° C.
Below 40° C., the problem is no longer posed.
Between these two thresholds, the problem increases with temperature.
It becomes critical from about 55° C.
Such an installation comprising a boiler and two exchangers generally gives satisfaction as regards operation, reliability and service life.
However, it has the drawback of a high cost price since it includes two distinct exchangers.
With the purpose of solving this difficulty, certain heating installers have modified the system by suppressing the second exchanger, and by having the sanitary water to be heated pass directly into the exchanger of the boiler in order to feed the storage tank.
Thus, such an installation for producing sanitary hot water comprises a boiler, a tank for storing hot water, an intake conduit for sanitary cold water, a conduit for feeding the boiler with water to be heated provided with a pump capable of ensuring circulation of the water to be heated towards the boiler when it is started and of preventing this circulation when it is at a standstill, a conduit for drawing sanitary hot water, a conduit for heated water flowing out of the boiler.
More specifically, said intake conduit for sanitary cold water is connected via a “T” connector, a so-called first connector, to the boiler feed conduit on the one hand, and to a so-called recirculation conduit on the other hand, opening out into the low portion of the hot water storage tank while the boiler outlet conduit and the water-drawing conduit open out into the central portion and into the upper portion of this tank respectively.
This installation is for example controlled in such a way that the water stored in the tank is permanently maintained at a temperature closed to 65° C., which is generally suitable for the relevant applications.
In the absence of water being drawn, the system is at a standstill, the boiler and pump are stopped.
When sanitary hot water is requested, a certain flow leaves the tank through the upper portion of this tank and is conveyed towards the point of use via the water-drawing conduit.
This causes the starting of the pump and of the boiler and an identical flow of sanitary cold water feeds the installation in order to compensate for the drawn water. At the first connector, this cold water is mixed with hot water from the low portion of the tank via the recirculation conduit, and this is the mixture (of warm water) which the pump drives back to the inlet of the boiler.
With this, it is possible to obtain operation in proper flow rate and temperature ranges of the pump and of the boiler, even if the drawn water flow rate is low or on the contrary very high.
A significant difficulty is encountered when, the sanitary water being loaded with lime, drawing of water stops. The boiler and the pump are then stopped by the control and regulation system.
Therefore, hot sanitary water, at a temperature close to 65° C. is left to stagnate in the tubing located upstream from the tank, including the inside of the boiler. The lowering of the temperature of this water in the absence of any specific device is slow. A deposit of limestone is therefore observed on the walls of the tubings of the installation as long as the temperature of the water remains above about 40° C.
This phenomenon, repeated at each drawing of water, may rather rapidly cause scale formation and make the exchanger inoperative, with which the boiler is equipped.
Another drawback encountered in this known installation lies in the fact that the energy dissipated during cooling of the stagnating water in the tubing, including in the exchanger, until the next drawing of water is definitively lost, which affects the overall energy yield of the installation.
The present invention aims at overcoming these difficulties by proposing within an installation of the aforementioned type, both eliminating or at the very least considerably reducing the risk of scale formation in its tubings while notably limiting energy losses which normally occur between successive water-drawing operations.
These objects are achieved, according to the invention, by the fact that:
As this will be seen further on in detail, it is possible by means of this arrangement to very rapidly and effectively cool the tubing located upstream from the tank, to below about 40° C., by circulating the cold water present in the small tank when drawing of water stops, which prevents the risk of limestone deposition.
In the first phase, overall “warming” of the water present in the tubing is observed, which remains at a medium temperature while awaiting the next drawing of water, which greatly limits heat losses.
Moreover, according to a certain number of additional, non-limiting features of the invention:
Other features and advantages of the invention will become apparent upon reading the following description of a preferred embodiment of the invention.
This description is made with reference to the appended drawings wherein:
With reference to
The installation includes a boiler 1 provided with a burner 60 fed with a combustible mixture, for example a gas/air or fuel oil/air mixture, by means of a fan 6 with an adjustable flow rate.
The function of the installation is to heat up sanitary cold water by means of this boiler, and to maintain the stored sanitary hot water at a given temperature, generally of the order of 65° C. in a storage tank 2 with a heat-insulated wall, from which it may be drawn on demand in order to feed one or more points of use.
Usually, the tank has a general cylindrical shape, with a vertical axis, with hemispherical end portions, and is supported on the ground by a base 20.
The burner 60, in the illustrated embodiment, is a cylindrical burner which is surrounded in a helicoidal tubular coil 10 in stainless steel in which the water to be heated flows.
The whole is housed in a case 11 provided with a sleeve for discharging the burnt and cooled gases (not shown), for example connected to a chimney flue opening into the outside of the dwelling.
During operation, when the burner is lit and the fan is running, the burning gases generated at the surface of the burner pass through the interstices between the turns of the coil in which the water to be heated circulates radially, from the inside to the outside, and impart heat to this water, both by conduction and by condensation.
The burnt and cooled gases are then discharged via the sleeve.
This type of condensation heating apparatus is well known and will not be described in detail herein in order not to unnecessarily burden the present description.
If need be, reference may usefully be made to patent documents EP-0678186 B1, WO 2004/036121 A1 or FR-A-2896856 mentioned in the preamble.
The intake of sanitary cold water EFS into the installation is achieved by means of a conduit 8 having a “T” connector 80 allowing branching of the water flow into a conduit 30 or into a conduit 13.
Conventionally, this connector 80 will be designated as “second T connector”.
The conduit 30 has a portion 3 with a notably widened diameter, forming the small storage tank.
Downstream from the small tank 3, the conduit 30 also has a “T” connector 90, which will be conventionally designated as “first T connector”. The latter allows branching of the water flow into a conduit 50 or into a so-called recirculation conduit 9.
The conduit 9 through its outlet orifice 900, opens into the interior of the tank 2 in the lower portion of the latter.
The conduit 50 is provided with an electrically controlled pump 5 and is connected to the inlet of the tubular coil 10 of the boiler 1.
The outlet conduit 40 of this tubular coil 10 is, as for it, provided with a three-way valve (solenoid valve) 4. To the latter are connected the aforementioned conduit 13 from the second connector 80 on the one hand and a conduit 12 which through its outlet orifice 120 opens into the interior of the tank 2, in the middle portion (approximately at half-height) of the latter, on the other hand.
The three-way valve 4 is adapted so as to be able to selectively connect the outlet conduit 40 of the boiler with the conduit 13 or with the conduit 12.
The sanitary hot water ECS outlet conduit or water-drawing conduit 7 emerges through an inlet orifice 70 in the upper portion of the tank 2.
A standard purging system 21 is mounted in the lower portion of the tank 2.
This installation further includes three temperature probes, i.e. one T2 which senses the temperature of the water conveyed by the conduit 40, at the exit of the boiler, another one T1 which senses the temperature of the water present in the low portion of the tank 2, at a level located above the orifice 900 (but underneath the orifice 120) the one into which opens said recirculation conduit 9 and the third one T3 which senses the temperature of the water present in the upper portion of the tank 2 in proximity to the inlet 70 of the water-drawing conduit 7.
According to an interesting feature of the invention, the capacity (contained volume) of the small tank 3 is substantially equal to the accumulated one of the conduits 9, 50, 10, 40, 13, 12 and 30 (apart from the small tank).
As an indication, for a boiler with a power of 50 kW, and a tank 2 having a capacity of 200 L, this capacity is of about 16 L.
The installation includes an electronic control unit UEC, into which predetermined operating set values have been introduced by an operator (heating specialist and/or user). These are notably the optimum flow rate of the pump, the power applied in the boiler 1, and the set outflow temperature of the sanitary hot water ECS.
Depending on the temperature values measured by the sensors T2, T2 and T3, the UEC will be able to control according to a given program, the running or stopping and the flow rate of the pump 5, the starting or stopping of the boiler 1 and its power (depending on the flow rate of the fan 6), as well as the change in the state of the valve 4, this by applying a process which will now be described with reference to
With reference to
The boiler is operating (the fan 6 is running and the burner 60 is lit). The valve 4 is thus oriented so that the conduits 40 and 12 communicate with each other, while the conduit 13 is isolated.
The pump 5 is also running and adjusted so as to provide a sufficient flow rate for properly operating the boiler, even for a low water-drawing flow rate i2. In practice, the flow rate of the pump 5 is independent of the water-drawing flow rate.
A flow of hot water i2 therefore leaves the tank through the upper orifice 70 of the tank 2 and passes into the conduit 7. In order to compensate it, an identical flow of cold water i1 (for example at a temperature of about 15° C.) arrives into the installation through the conduit 8. It cannot penetrate into the conduit 13, the other end of which is blocked (valve 4 is closed) and therefore entirely enters the conduit 30 and the small tank 3, in order to emerge therefrom via the first connector 90 and to feed the pump 5. It is then mixed with a flow i3 which flows out of the base of the tank 2 through the recirculation conduit 9.
All in all, it is therefore a mixture of cold water (for example at about 15° C.) and of hot water (for example at about 65° C.) which is driven back by the pump 5 towards the boiler 1, with a flow rate j=i1+i3.
This mixture is heated to a temperature of 65° C., monitored by the probe T2 and is distributed into the central portion of the tank 2 through the conduit 12 (arrows j).
This hot water is distributed inside the storage tank 2 while ensuring some mixing and homogenization of the temperature therein because a fraction i2 flows out of it from the top and another fraction i3 flows out from the bottom.
With reference to
In a first phase which may in practice correspond to a few seconds, the UEC maintains the pump 5 and the boiler 1 running without changing the position of the valve 4.
Under these conditions, mixing of the hot water with a flow k of the water of the tank 2 being circulated in a closed circuit is observed, the flow path up to the boiler passing through the conduits 9 and 50, and the return path to the tank through the conduits 40 and 12. The small tank 3, filled with cold water, remains isolated. The probe T2 regulates the power of the burner, which decreases gradually as the temperature rises in the tank 2. When the whole of the tank is at the intended temperature, as measured by the probes T1 and T3, the UEC controls the stopping of the burner 60.
At this moment switching of the valve 4 is performed into the position illustrated in
The pump 5 is kept running.
Circulation of water in a closed circuit symbolized by the arrows I in
By this arrangement, the cold water contained in the small tank 3 very rapidly causes cooling of the boiler coil 10, and the mixture of cold water provided by the small tank 3 with the dose of hot water—with a substantially equivalent volume—which is found in the tubing applied here, results in an intermediate final temperature, of the order of 35-40° C.
Finally, by suitable timing, the UEC orders stopping of the pump 5.
The water present in the conduits is thus at a too low temperature so that no limestone is deposited on the walls of these conduits with the risk of scaling them, according to the sought goal.
In the absence of water being drawn, the tank 2 remains isolated and the hot water which it contains remains at the set temperature, for example 65° C.
The UEC may be programmed so that in the case of “small amounts of drawn water”, corresponding to low flow rates and/or to short periods of requesting sanitary hot water, the system remains in the previous state: boiler 1 switched off, pump 5 stopped and valve 4 in the bypass position.
This situation is illustrated in
In the case of small amounts of water being drawn, it is not advisable to start the boiler, from the moment that the reserve of hot water available in the tank 2 is sufficient for satisfying them. This notably avoids stopping/starting phases likely to be detrimental to the service life of the installation, and energy losses related to operating the boiler over short periods.
In this configuration, the sanitary cold water flow m entering through the conduit 8 is the same as that of hot water leaving the tank 2 through the conduit 7.
In a first phase, the inflowing cold water passes into the conduit 30, expels the water at an intermediate temperature which occupies this conduit, including in the small tank 3, and the mixture is driven back through the bypass conduit 9 at the base of the tank 2.
A large portion of the heat recovered in the previous step is therefore transferred in this way from the small tank 3 to the tank 2 which is favorable for the overall energy balance.
If the “small water-drawing operations” continue, either continuously or on an ad hoc basis (single shot), it is finally the cold water which arrives at the base of the tank 2. However, a relatively clear temperature transition is observed inside the latter between the lower volume (at a low temperature) and the upper volume (at a high temperature) of the water present in the tank. The level of this transient area gradually rises depending on the drawn volume and ends up by reaching the level of the probe T1.
Below a determined threshold value of the temperature at this level, the UEC orders restarting of the boiler, and brings the installation back to its initial operating state corresponding to that of
On the alternative installation according to the invention which is illustrated in
This embodiment is essentially distinguished from the previous one in that the storage tank—designated here as 3′—is not separated here from the storage tank—designated here as 2′—, but is an integral part of it.
More specifically, the small tank 3′ occupies the inner volume of the hemispherical bottom cap of the tank 2′ and is separated from the inner volume of the latter by a horizontal partition 22.
The cold water intake conduit 8 opens out directly into the tank 3′ through an outlet orifice 810.
The first “T” connector designated herein as 91, is positioned inside the storage tank 2′.
It comprises a vertical branch 910 which passes through the partition 22, while its horizontal branch on one side opens out through tubing 92 into the tank 2′, just above this partition 22; its other horizontal tubing is connected to a bypass conduit 93 connected to the pump 5.
This installation works in the same way that the one previously described.
In the case of normal drawing of sanitary hot water, the boiler 1 and pump 5 running, with the valve 4 having the conduits 40 and 12 communicate with each other, the sanitary cold water enters through the conduit 8 in the constitutive compartment 3′ of the small storage tank, flows out therefrom through the tubing 910, is mixed with hot water from the tank 2′ through the tubing 92, and this mixture is driven back towards the boiler through the conduits 93 and 50 by means of the pump 5. The water heated by the boiler 1 returns into the tank through the conduits 40 and 12 via the valve 4.
In the case of stopping the drawing of sanitary hot water, in a first phase, the UEC maintains the pump 5 and boiler 1 running, without changing the position of the valve 4. Mixing of the hot water is then observed with it being circulated in a closed circuit, the flow path to the boiler passing through the conduits 93 and 50, and the return path to the tank through the conduits 40 and 12. The small tank 3′, filled with cold water remains isolated. The probe T2 regulates the power of the burner which decreases gradually as the temperature rises in the tank 2′. When the whole of the tank is at the intended temperature as measured by the probes T1 and T3, the UEC orders stopping of the burner 60.
At this moment, the switching of the valve 4 into the position having the conduits 40 and 13 communicate with each other, is performed, the pump 5 being kept running.
Circulation of water in a closed circuit is then observed from the small tank 3′ towards the boiler (switched-off) 1 via the tubing 910, the conduit 93, the pump 5 and the conduit 50, and then return to the small tank 3′ via the conduit 40, the three-way valve 4, the bypass conduit 13 and the conduit 8.
By means of this arrangement, the cold water contained in the small tank 3′ very rapidly causes cooling of the boiler coil 10, in order to result in an intermediate final temperature of the order of 35-40° C.
The UEC then orders by timing the stopping of the pump 5.
The water present in the conduits is thus at a too low temperature so that no limestone is deposited on the walls of these conduits with the risk of scaling them, according to the sought goal.
In the absence of water being drawn, the tank 2′ remains isolated and the hot water which it contains remains at the set temperature, for example 65° C.
As in the first embodiment, the UEC may be programmed so that in the case of “small amounts of water being drawn” corresponding to low flow rates and/or to short periods of request of sanitary hot water, the system remains in the previous state (boiler switched off, pump stopped and valve in the bypass position).
This avoids the occurrence of untimely stopping/starting phases for “small amounts of water being drawn”.
In this configuration, the sanitary cold water flow rate entering through the orifice 810 of the conduit 8 is the same as that of hot water leaving the tank 2 through the orifice 70 of the conduit 7.
In a first phase, the inflowing cold water expels the water at an intermediate temperature which occupies the small tank 3′, and the mixture is driven back through the tubings 910 and 92 of the connector 91 in order to be diffused at the base of the tank 2.
With continuation of small amounts of water being drawn, i.e. continuously, it is finally cold water which arrives at the base of the tank 2, with a relatively clear temperature transition between the lower volume (at low temperature) and the upper volume (at high temperature) of the water present in the tank. The level of this transient area gradually rises depending on the volume of drawn water, and ends up by reaching the level of the probe T1.
Below a determined threshold value of the temperature at this level, the UEC orders restarting of the boiler and brings the installation back into its normal initial operating state.
| Number | Date | Country | Kind |
|---|---|---|---|
| 08 51465 | Mar 2008 | FR | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2009/052401 | 2/27/2009 | WO | 00 | 11/9/2010 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2009/112385 | 9/17/2009 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 2079419 | Munters | May 1937 | A |
| 2515652 | Hunt et al. | Jul 1950 | A |
| 3045494 | Gerarde | Jul 1962 | A |
| 3177659 | Berman | Apr 1965 | A |
| 3522909 | Arant | Aug 1970 | A |
| 3645420 | Machado | Feb 1972 | A |
| 3705574 | Duncan | Dec 1972 | A |
| 3929154 | Goodwin | Dec 1975 | A |
| 4046320 | Johnson et al. | Sep 1977 | A |
| 4096039 | Carnine et al. | Jun 1978 | A |
| 4102752 | Rugh, II | Jul 1978 | A |
| 4155506 | Brosenius | May 1979 | A |
| 4175698 | Brosenius | Nov 1979 | A |
| 4243522 | Ter-Borch et al. | Jan 1981 | A |
| 4281519 | Spath et al. | Aug 1981 | A |
| 4302942 | Charters et al. | Dec 1981 | A |
| 4363221 | Singh | Dec 1982 | A |
| 4374506 | Whalen | Feb 1983 | A |
| 4406136 | Picchiottino | Sep 1983 | A |
| 4408960 | Allen | Oct 1983 | A |
| 4412526 | DeGrose | Nov 1983 | A |
| 4438881 | Pendergrass | Mar 1984 | A |
| 4624190 | Cappi | Nov 1986 | A |
| 4690102 | Sundquist | Sep 1987 | A |
| 4714821 | Jakobsson | Dec 1987 | A |
| 4743194 | Stellaccio | May 1988 | A |
| 5174123 | Erickson | Dec 1992 | A |
| 5233970 | Harris | Aug 1993 | A |
| 5256313 | Crafton | Oct 1993 | A |
| 5262013 | Beal et al. | Nov 1993 | A |
| 5281309 | Greene | Jan 1994 | A |
| 5396812 | Peterson | Mar 1995 | A |
| 5441606 | Schlesinger et al. | Aug 1995 | A |
| 5535596 | Todack | Jul 1996 | A |
| 5618431 | Kondo et al. | Apr 1997 | A |
| 5662779 | Greene et al. | Sep 1997 | A |
| 5881952 | MacIntyre | Mar 1999 | A |
| 6251279 | Peterson et al. | Jun 2001 | B1 |
| 6275655 | Rixen | Aug 2001 | B1 |
| 6277247 | Popov | Aug 2001 | B1 |
| 6453938 | Ebster | Sep 2002 | B1 |
| 6594447 | Rixen | Jul 2003 | B2 |
| 6604376 | Demarco et al. | Aug 2003 | B1 |
| 6830661 | Land | Dec 2004 | B1 |
| 6866092 | Molivadas | Mar 2005 | B1 |
| 7089955 | Komro, Sr. | Aug 2006 | B1 |
| 7217343 | Land | May 2007 | B2 |
| 7294258 | Leiter et al. | Nov 2007 | B2 |
| 7298968 | Boros et al. | Nov 2007 | B1 |
| 7302916 | LeMer et al. | Dec 2007 | B2 |
| 20020035972 | Suzuki et al. | Mar 2002 | A1 |
| 20030042321 | Tacchi | Mar 2003 | A1 |
| 20030131806 | Suzuki et al. | Jul 2003 | A1 |
| 20050056594 | Nunez | Mar 2005 | A1 |
| 20050103622 | Jha et al. | May 2005 | A1 |
| 20050235984 | Trihey et al. | Oct 2005 | A1 |
| 20060054305 | Ye | Mar 2006 | A1 |
| 20060102106 | Le Mer et al. | May 2006 | A1 |
| 20060196450 | Le Mer et al. | Sep 2006 | A1 |
| 20060196955 | Moxon et al. | Sep 2006 | A1 |
| 20060272933 | Domen et al. | Dec 2006 | A1 |
| 20070170273 | McIllwain | Jul 2007 | A1 |
| 20070272539 | Land | Nov 2007 | A1 |
| 20080029612 | Peckham et al. | Feb 2008 | A1 |
| 20100025488 | Park et al. | Feb 2010 | A1 |
| 20100051713 | Back et al. | Mar 2010 | A1 |
| 20110197600 | Hamada et al. | Aug 2011 | A1 |
| 20110259437 | Thomasson | Oct 2011 | A1 |
| 20130032036 | Zhong et al. | Feb 2013 | A1 |
| 20130075245 | Frick | Mar 2013 | A1 |
| 20130125842 | Frick | May 2013 | A1 |
| 20130319348 | Hughes et al. | Dec 2013 | A1 |
| 20140021032 | Frick | Jan 2014 | A1 |
| 20140021033 | Frick | Jan 2014 | A1 |
| 20150090199 | Min | Apr 2015 | A1 |
| Number | Date | Country |
|---|---|---|
| 1450322 | Oct 2003 | CN |
| 200982707 | Nov 2007 | CN |
| 0678186 | Oct 1995 | EP |
| 0781968 | Jul 1997 | EP |
| 1795818 | Jun 2007 | EP |
| 2398976 | Feb 1979 | FR |
| 2847972 | Jun 2004 | FR |
| 2896856 | Aug 2007 | FR |
| 2004036121 | Apr 2004 | WO |
| 2005071322 | Aug 2005 | WO |
| Entry |
|---|
| International Search Report, PCT/EP2009/052401, dated Jul. 3, 2009. |
| Number | Date | Country | |
|---|---|---|---|
| 20110132279 A1 | Jun 2011 | US |
