DE102009002482A1 - Dryer for use as e.g. circulating air dryer to dry laundry, has electrical switches that are arranged such that given number range for relative humidity in drying process is maintained in process controller by influencing actuators - Google Patents

Abstract

The dryer (1) has a drying chamber (3) for articles to be dried, a process air channel (2), an electrical heater (11) for heating the air, a blower (12) and a process controller (10). Two humidity sensors (15, 16) measure the humidity of air. An electrical switch evaluates the humidity signals output by the sensors. Another electrical switch influences actuators (12, 13) in the controller for operation of dryer. The electrical switches are arranged such that given number range for relative humidity in a drying process is maintained in the controller by influencing the actuators. An independent claim is also included for a method for operating a dryer.

Description

The The invention relates to a dryer with a drying chamber for objects to be dried, a process air duct, a Heating for heating the process air and a first Blower, a program control, a heat exchanger and a humidity sensor arrangement for measuring humidity signals as a measure of the humidity of the process air, and a preferred method for its operation.

Of the The term dryer as used herein includes devices that can only be used for drying laundry, the actual dryer, and washer-dryer, in which both a Drying method and a washing process performed can be. As it relates herein in particular to the dryer functions arrives, is in the following no longer expressly It should be noted that the invention also encompasses washer-dryers without while the scope of the invention, however, to actual dryer restrict.

in the Generally, tumble dryers are used as exhaust or condensation dryers operated. A condensation dryer, whose operation on the Condensation of evaporated by means of circulating process air Moisture from the laundry is not needed Exhaust hose and allows energy recovery from the heated process air, for example by use a heat pump. The costs incurred in the condensation dryer Condensate is collected and either pumped off or by manual Emptying a collection container disposed of.

at In contrast, an exhaust air dryer will generally be the one after passage air laden with moisture through a laundry drum out of the dryer. A heat recovery is not excluded, but often does not take place - not lastly because the exhaust air dryer is as simple as possible built and cheap to acquire.

Exhaust air dryers with heat recovery are known in principle. That's how it describes DE 30 00 865 A1 Such a clothes dryer with heat recovery. The tumble dryer consists of a container receiving and moving the laundry, into which a supply air flow heated by a heating element opens, while the moist hot air is conducted as exhaust air via an outlet. In the supply air flow, a heat exchanger is arranged in front of the heating element, which is flowed through by the moist hot exhaust air from the container, so that heat is transferred from the exhaust air to the supply air.

The Energy efficiency of an exhaust air dryer can also by a recirculation system can be improved. This is where the moisture partially laden process air from the laundry in the drying chamber returned to the drying process via the heater. The disadvantage here is that of the laundry in the Drying chamber resulting lint get to the heater can. This can lead to a lethargy of the downstream Airways including the heater lead. It is therefore appropriate Countermeasures such. B. the use of filter devices to take. Anyway, more components are required.

Also The disadvantage is that due to the higher relative humidity the exhaust air and the process-related low process air flow significantly More condensate in the usually long exhaust duct arises and itself also deposit more lint in the exhaust duct.

The for a user of a drier for carrying A drying process acceptable time can be very different be. In extreme cases, a drying process must be as quick as possible expire, or the time to be played at all not matter. This is the case, for example, when a drying process is over Night can be performed. At a less strict time limit In principle, a drying process can be performed more flexibly become.

In front It is an object of the present invention to provide a Dryers with improved energy efficiency and a corresponding process provide.

The Solution of this problem is achieved according to this invention through a dryer with the characteristics of the corresponding independent Patent claim and the method of the corresponding independent Claim. Preferred embodiments of the dryer according to the invention are in corresponding dependent claims listed. Preferred embodiments of the invention Trockners correspond to preferred embodiments of the inventive method and vice versa, even if this is not explicitly stated herein.

The invention thus relates to a dryer with a drying chamber for objects to be dried, a process air duct, a heater for heating the process air and a first fan, a program control, a heat exchanger and a humidity sensor arrangement for measuring humidity signals as a measure of a humidity of the process air. In the program control, first means for evaluating the moisture signals measured by the humidity sensor arrangement and second means for influencing actuators for the operation of the dryer are present and are such are directed that a stored in the program control predetermined range of numbers for the relative humidity in a drying process by influencing the actuators can be met.

in the The dryer according to the invention is or are a Power of the heater and / or a rotation number of the first blower preferably variable; Thus, according to the invention, the Heating and the first blower as actuators for the operation, to which corresponding second means of program control have to act. Is - for example, in a cooling air duct for conveying cooling air as an air-to-air heat exchanger trained heat exchanger, a second blower provided, this can also be used as an actuator. Also correspondingly controllable components of the dryer are conceivable as actuators, such as valves and valves for Control of the flow of process air or, if given, cooling air.

The first and second means within the program control are in particular as electrical circuits, possibly as programmed accordingly Circuits in program control, executed.

Preferably the power of the heating is variable. The variation of the performance This can be achieved by varying the power of the heater itself can be, but also by having a single or multi-level Heating for different lengths and frequently switched on and off can be.

Of the The term "heating" as used herein means in particular an electric heater.

According to the invention preferably a one or two-stage heating used. In a preferred embodiment of the dryer, the first Heat level on a smaller power than the second heating level. in this connection the first heating stage preferably has a power in the range from 200 to 600 watts, preferably from 300 to 500 watts, on and the second heating stage has a power in the range of 1000 to 1800 Watt, preferably in the range of 1200 to 1600 watts. By suitable sole use or interconnection of the two heat levels can be four switching states of the heating with four form different heating capacities.

In a preferred embodiment, the inventive Dryer an air-air heat exchanger with a cooling air duct, in which there is a second fan. A rotation number of the second blower is preferably variable, whereby the second blower can then be used as an actuator. In connection with a simple heating, in particular an electric heater As just described, this embodiment results of the dryer according to the invention thus classical Condensation dryer.

At the first blower and / or the second blower the variable rotation number preferably in the range of 1000 to 5000, more preferably in the range of 1500 to 3500 and more particularly preferably in the range of 2000 to 3000 revolutions / min.

in the The dryer according to the invention can be the moisture sensor arrangement Humidity sensors in various places include, for example between the drum and the heat exchanger or between the heat exchanger and heating. There are within the scope of the invention arrangements with only a humidity sensor and arrangements with several humidity sensors conceivable. The specified number range stored in the program control depends on the relative humidity of the process air in general, the arrangement of the humidity sensor in the process air duct from.

A related first preferred alternative of the invention Trockners is characterized by the fact that the moisture sensor arrangement a Moisture sensor that covers between the drum and the heat exchanger is arranged. A related second preferred alternative of the dryer according to the invention characterized thereby in that the humidity sensor arrangement comprises a humidity sensor, which is arranged between the heat exchanger and the heater is.

Of the Heat exchanger can be an air-to-air heat exchanger or the heat sink of a heat pump. For the case that in the dryer according to the invention a Heat pump is used, this is preferably power controlled.

In a dryer equipped with a heat pump, the cooling of the warm, moisture-laden process air essentially takes place in a heat sink, which is a heat exchanger, in which the heat pump extracts heat from the process air flowing through it. In the heat sink, this transferred heat can be used to evaporate a refrigerant; In such a heat pump, the heat sink is also referred to as an evaporator. The refrigerant evaporated due to the heating circulates in a closed circuit; it is supplied via a compressor of the heat source of the heat pump, wherein the heat source is a heat exchanger through which the process air flowing through heat is supplied from the heat pump. In the case of the heat pump with circulating refrigerant the refrigerant is condensed or liquefied in the heat source, which is why the heat source is referred to as a condenser in this case. Due to the condensation of the gaseous refrigerant heat is released in the condenser, which is used to heat the process air or the supply air before entering the drying chamber. The liquefied refrigerant is returned to the evaporator via a throttle in the corresponding heat pump. In the evaporator, the internal pressure of the refrigerant is reduced to such an extent that it can be vaporized in the evaporator with renewed absorption of heat.

In Another preferred embodiment is the at least a heat exchanger an air-to-air heat exchanger. In this case, preferably the moist, hot process air used from the drying chamber for heating supply air, which is then fed to the drying chamber. Cross here preferably in the air-to-air heat exchanger of the exhaust duct and the supply air duct.

in the dryers according to the invention can also at the same time a heat pump and an air-to-air heat exchanger be used. For example, an air-to-air heat exchanger in the exhaust duct between the junction of the circulating air duct and the Be arranged evaporator of the heat pump.

In a preferred embodiment of the invention, the Dryer on a supply air duct and an exhaust duct, wherein the process air duct after the drying chamber at a branch in a recirculating air duct leading to the heating and the exhaust air duct splits. In this case, the recirculation channel preferably combines before heating with the supply air duct. In the recirculation channel is also preferably arranged a first controllable closure device. In addition, in the supply air duct is preferably a second controllable closure device arranged.

is the corresponding dryer according to the invention additionally as already described, equipped with a heat pump, so can the heat released in the heat source in the supply air duct for heating supply air or after unification of supply air duct and recirculating air duct for heating the combined Supply air and recirculated air are used.

object The invention is also a method for operating a Dryer with a drying chamber for drying Objects, a process air duct, a heater to Heating the process air and a first blower, a program control, a heat exchanger and a Humidity sensor arrangement for measuring humidity signals as a measure of a humidity of the process air, the first means in the program control for Evaluation of the humidity signals measured by the humidity sensor arrangement and second means in the program control for influencing Actuators for operation, allowing one in the program control stored predetermined number range for the relative Humidity of the process air maintained in a drying process can be. The humidity sensor arrangement measures in the process air the relative humidity as a humidity signal, the humidity signal is specified with a preset stored in the program control Number range for the relative humidity of the process air compared, and in the event that the measured relative Humidity outside the specified number range is, the influencing of at least one actuator is varied.

in this connection it is preferable that the rotation number of the first blower reduced and / or a performance of the heating is reduced, if the measured relative humidity is below the specified one Number range is.

is a second fan exists, so can its rotation number be varied in a suitable manner. Thus, it is preferred according to the invention that a rotation number of a second blower in a Cooling air duct is varied until the measured relative Humidity is within the specified range of numbers.

In a preferred embodiment of the invention Method in which the dryer a supply air duct and a Has exhaust duct, wherein the process air duct after the drying chamber at a junction in a recirculating air channel leading to the heating and splits the exhaust duct, becomes a portion of a process air flow in the recirculating air duct, based on a process air flow between the drum and the diversion, varies until the measured relative Humidity is within the specified range of numbers.

A Another preferred embodiment of the invention Method provides that the given range of relative Humidity is between 70% and 100%, with the humidity sensor arrangement measures the humidity signal by means of a humidity sensor, the between the drum and the heat exchanger is arranged.

A to the previous embodiment alternative further preferred Embodiment of the invention Method provides that the given range of relative Humidity is between 80% and 100%, with the humidity sensor arrangement measures the humidity signal by means of a humidity sensor, the between the heat exchanger and the heater is arranged.

With In particular, consideration is given to these two embodiments taken on the different measuring conditions for a humidity sensor depending on its placement in the process air duct.

The inventive method runs in particular then energy efficient when the relative humidity of the Process air after discharge from the drum as high as possible is. On the other hand, it was found that to carry a method according to the invention, in which a the highest possible relative humidity of the process air is given is, a longer period is needed.

In a particularly preferred embodiment of the invention is therefore a user of the invention Trockners given the opportunity between different Variants of the drying process to choose which in terms of energy efficiency and speed, with generally a higher speed of the drying process associated with poorer energy efficiency. In addition to one particularly fast and a particularly slow variant could a user of the dryer the opportunity to intervene lying variants are given. These variants would be generally by specifying different areas given for the relative humidity of the process air. It should be noted that for a longer duration of a drying process with an increased loss of heat to the environment of the dryer must be expected; increased by such To avoid losses or at least to keep them sufficiently low, Therefore, if necessary, appropriate for a suitable insulation endangered components of the dryer such as drum, process air duct and the like.

Of the Users could such variants via a control unit adjust at the dryer. These could be marked, for example be as "60% energy saving, 40% speed", corresponding to a range of relative humidity of Process air of z. 70 to 100%, or as "80% energy saving, 20% speed ", corresponding to an area for the relative humidity of the process air of z. 80% to 100%.

The Opting for an energy-efficient program might be appropriate be displayed by a visual display device. An energy saving program, that at a very high lower value for the relative Moisture of the process air begins, for example indicated by a particularly intense glowing green become.

The Compliance with the given range of numbers for the relative Humidity can also be achieved by controlling the proportions of circulating air and exhaust air of a suitably constructed dryer influenced become. For better control of the proportions of circulating air and exhaust air according to an embodiment of the invention Trockners is preferably a first controllable in the recirculating air channel Closure device, such as a flap, arranged, the completely or partially opened or closed can be. It is also preferred that in the supply air duct a second controllable closure device is arranged.

Of the Umluftkanal is preferably designed such that it has a branch from 30 vol .-% to 50 vol .-% of a process air flow in the process air duct after allowed the exit from the drying chamber.

By the use of a recirculating air duct or the passage of the hot, circulating air laden with moisture through the recirculating air duct to the heater If the heating power remains the same, the air temperature is before the Heating raised. Due to the increased airflow over however, the heater can set the drum inlet temperature within the allowable range stay. To set a desired drum inlet temperature or drum outlet temperature may in this embodiment the invention of the air flow of the exhaust air, the circulating air and / or the Zuluft be regulated, for example by using a first controllable closure device in the recirculation channel and / or a second controllable closure device in the supply air duct. A corresponding Control of the heating would also be within the scope of the invention possible.

According to the invention it is preferred if exhaust air, supply air and / or refrigerant each in a cross or countercurrent process by the corresponding Heat exchangers are guided.

Of the dryer according to the invention has the advantage that the energy efficiency is significantly increased. A user The dryer may be available depending on which it is Standing time decide whether a particularly fast or a particularly energy-efficient drying process performed is to be, whereby intermediate stages are possible.

Further details of the invention will become apparent from the following description of non-limiting embodiments of the dryer according to the invention and a method using this dryer. Reference is made to the 1 and 2 ,

1 shows a vertical section through a dryer according to a first embodiment, in which a heat recovery takes place by means of an air-to-air heat exchanger.

2 shows a vertical section through a dryer according to a second embodiment, in which a heat recovery takes place by means of a heat pump.

The in 1 illustrated dryer 1 According to a first embodiment is designed as a circulating air dryer and conventional condensation dryer. The dryer 1 has a drum rotatable about a horizontal axis 3 as a drying chamber 3 on, within which carriers 4 are attached to the movement of laundry during a drum rotation. Process air is generated by means of a first blower 12 in a process air duct 2 via an electric heater 11 through a drum 3 guided. After passing through the drum 3 the moist, warm process air becomes an air-to-air heat exchanger 25 passed, in which the process air cooled and after condensation of the moisture contained in it again to the heater 11 and finally back to the drum 3 to be led. The moisture precipitated as condensate is collected in a condensate tray, not shown here, from where it can be removed, for example, by pumping.

In particular, it is in the dryer 1 from the heater 11 heated air from behind, ie from a door 5 opposite side of the drum 3 through whose perforated bottom into the drum 3 passed, comes there with the laundry to be dried in contact and flows through the filling opening of the drum 3 to a lint filter 6 within a door closing the filling opening 5 , Subsequently, the process air flow in the door 5 deflected downwards and reaches the air-to-air heat exchanger 25 , Through the air-to-air heat exchanger 25 goes a cooling air duct 14 in which there is a second blower 13 for conveying the room air supplied to the dryer as cooling air. Between the air-to-air heat exchanger 25 and the drum 3 there is a (first) humidity sensor 16 and between the first fan 12 and the air-to-air heat exchanger 25 there is a (second) humidity sensor 15 , these two humidity sensors 15 and 16 are primarily to be understood as alternatives; but it is also conceivable together as a moisture sensor arrangement 15 . 16 to be provided and used.

In the embodiment of the dryer shown here, the speeds of the first blower 12 and second blower 13 variable. Likewise, the heating power of the heater 11 variable. The two blowers 12 and 13 as well as the heating 11 Thus, in conjunction with corresponding associated second means in a process control 10 , as actuators 11 . 12 . 13 be used for the drying process.

That of at least one of the humidity sensors 15 and 16 Registered humidity signals as a measure of the relative humidity of the process air are the first means of program control 10 fed, in which a predetermined number range for the relative humidity of the process air is stored. The over the humidity sensor 15 or 16 certain value of the relative humidity is compared with the predetermined number range for the given relative humidity of the process air. If the specific value of the relative humidity is outside the range of numbers, according to the embodiment of FIG 1 corresponding actuators 11 . 12 . 13 by associated second means of process control 10 influenced, in this case the rotational speeds of the first or second blower and the power of the heater 11 suitably varies until the relative humidity of the process air is within the predetermined number range.

At the in 2 shown second embodiment of the dryer, a heat pump is used instead of an air-to-air heat exchanger. In addition, the dryer of this embodiment is configured as a vented dryer with a controllable proportion of circulating air.

When drying the 2 becomes the process air duct 2 via a supply air duct 23 Room air supplied or through the first fan 12 sucked. This process air is produced by means of the condenser 28 the heat pump and the heater 11 heated and for drying damp laundry in the drum 3 directed. In particular, the heated process air from the rear, ie from a door 5 opposite side of the drum 3 through whose perforated bottom into the drum 3 passed, comes there with the laundry to be dried in contact and flows through the filling opening of the drum 3 to a lint filter 6 within a door closing the filling opening 5 , Subsequently, moist, warm process air in the door 5 turned down and at a turnoff 19 in a recirculating air stream in a recirculating air duct 20 and in an exhaust air flow in an exhaust duct 21 split. In the recirculation channel 20 is a first controllable closure device 26 arranged.

In the exhaust duct 21 is the evaporator 27 a heat pump 27 . 28 . 29 . 30 in which the process air (here: exhaust air) is cooled and after condensation of the moisture contained in it to an exhaust air outlet 22 is guided, where it is supplied to the room air. The moisture deposited as condensate is stored in a condensate tray 24 collected from where it can be removed for example by pumping.

That in the evaporator 27 evaporated refrigerant of the heat pump 27 . 28 . 29 . 30 is about one compressor 29 to the liquefier 28 directed. In the liquefier 28 the refrigerant liquefies under heat to those in the supply air duct 23 flowing process air. The now in liquid form refrigerant is via a throttle valve 30 turn to the evaporator 27 passed, whereby the refrigerant circuit is closed.

The in the recirculation channel 20 branched off part of the drying chamber 3 exiting warm, moisture laden process air is through the heater 11 again in the drying chamber 3 guided.

At the in 2 embodiment shown unite before the electric heater 11 the branched process air from the recirculation air duct 20 as well as in the liquefier 27 the heat pump 27 . 28 . 29 . 30 preheated supply air. The supply air flow may be through a second controllable closure device 18 (For example, flaps) are regulated. Overall, the proportion of circulating air with coordinated use of the first controllable closure device 26 and the second controllable closure device 18 be managed.

Between the evaporator 28 (or the branch 19 ) and the drum 3 there is a humidity sensor 16 , The from the humidity sensor 16 Registered humidity signals as a measure of the relative humidity of the process air are controlled by a program 10 fed, in which a predetermined number range for the relative humidity of the process air is stored. The over the humidity sensor 16 certain value of the relative humidity is compared with the predetermined number range for the given relative humidity of the process air. If the specific value of the relative humidity is outside the range of numbers, according to the embodiment of FIG 2 the number of rotations of the first blower 12 and / or the power of the heater 11 varies, and / or the proportion of circulating air and exhaust air changed as described until the relative humidity of the process air is within the predetermined number range.

The drum 3 will be at the in 1 and 2 shown embodiments on the rear floor by means of a pivot bearing and front by means of a bearing plate 7 stored, with the drum 3 with a brim on a sliding strip 8th on the bearing plate 7 rests and is held at the front end. The control of the condensation dryer via a control device 10 by the user via a control unit 9 can be regulated.

QUOTES INCLUDE IN THE DESCRIPTION

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Cited patent literature

• - DE 3000865 A1 [0005]

Claims (16)

Dryer ( 1 ) with a drying chamber ( 3 ) for objects to be dried, a process air duct ( 2 ), a heater ( 11 ) for heating the process air and a first blower ( 12 ), a program control ( 10 ), a heat exchanger ( 25 . 27 ) and a humidity sensor arrangement ( 15 . 16 ) for measuring humidity signals as a measure of a humidity of the process air, characterized in that in the program control ( 10 ) first means for evaluating the of the humidity sensor arrangement ( 15 . 16 ) measured moisture signals and second means for influencing actuators ( 11 . 12 . 13 . 18 ) are provided for the operation of the dryer and are set up in such a way that one in the program control ( 10 ) given relative range of relative humidity in a drying process by influencing the actuators ( 11 . 12 . 13 . 18 ) can be maintained. Dryer ( 1 ) according to claim 1, characterized in that a power of the heating ( 11 ) and / or a rotation number of the first blower ( 12 ) are variable. Dryer ( 1 ) according to claim 1 or 2, characterized in that it comprises an air-air heat exchanger ( 25 ) with a cooling air duct ( 14 ), in which a second blower ( 13 ) is located. Dryer ( 1 ) according to claim 3, characterized in that a rotation number of the second blower ( 13 ) is variable. Dryer ( 1 ) according to one of claims 1 to 4, characterized in that the humidity sensor arrangement ( 15 . 16 ) a humidity sensor ( 16 ) between the drum ( 3 ) and the heat exchanger ( 25 . 27 ) is arranged. Dryer ( 1 ) according to one of the preceding claims, characterized in that the humidity sensor arrangement ( 15 . 16 ) a humidity sensor ( 15 ) between the heat exchanger ( 25 . 27 ) and the heating ( 11 ) is arranged. Dryer ( 1 ) according to one of the preceding claims, characterized in that it has a supply air duct ( 23 ) and an exhaust duct ( 22 ), wherein the process air channel ( 2 ) after the drying chamber ( 3 ) at a branch ( 19 ) in one for heating ( 11 ) leading recirculating air duct ( 20 ) and the exhaust duct ( 22 ) splits up. Dryer ( 1 ) according to claim 7, characterized in that the recirculating air duct ( 20 ) in front of the heater ( 11 ) with the supply air duct ( 23 ) united. Dryer ( 1 ) one of claims 7 and 8, characterized in that in the recirculating air channel ( 20 ) a first controllable closure device ( 26 ) is arranged. Dryer ( 1 ) according to one of claims 7 to 9, characterized in that in the supply air duct ( 23 ) a second controllable closure device ( 18 ) is arranged. Method for operating a dryer ( 1 ) with a drying chamber ( 3 ) for objects to be dried, a process air duct ( 2 ), a heater ( 11 ) for heating the process air and a first blower ( 12 ), a program control ( 10 ), a heat exchanger ( 25 . 27 ) and a humidity sensor arrangement ( 15 . 16 ) for measuring humidity signals as a measure of a humidity of the process air, first means in the program control ( 10 ) for the evaluation of the humidity sensor arrangement ( 15 . 16 ) measured moisture signals and second means in the program control ( 10 ) for influencing actuators ( 11 . 12 . 13 . 18 ) for operation, so that one in the program control ( 10 ) can be maintained in a drying process stored predetermined number range for the relative humidity of the process air, characterized in that the humidity sensor arrangement ( 15 . 16 ) in the process air measures the relative humidity as a humidity signal, the humidity signal with one in the program control ( 10 ) compared predetermined number range for the relative humidity of the process air, and in the event that the measured relative humidity is outside the predetermined number range, influencing at least one actuator ( 11 . 12 . 13 . 18 ) is varied. Method according to claim 11, characterized in that the number of rotations of the first blower ( 12 ) and / or a power of the heating ( 11 ) is lowered when the measured relative humidity is below the predetermined number range. Method according to one of claims 11 and 12, characterized in that a rotation number of a second blower ( 13 ) in a cooling air channel ( 14 ) is varied until the measured relative humidity is within the given range of numbers. Method according to one of claims 11 to 13, characterized in that the dryer a supply air duct ( 23 ) and an exhaust duct ( 22 ), wherein the process air channel ( 2 ) after the drying chamber ( 3 ) at a branch ( 19 ) in one for heating ( 11 ) leading recirculating air duct ( 20 ) and the exhaust duct ( 22 ), and a portion of a process air flow in the recirculating air duct, based on a process air flow between the drum ( 2 ) and the branch ( 19 ), is varied until the measured relative humidity is within the given range of numbers. Method according to one of claims 11 to 14, characterized in that the predetermined range of relative humidity is between 70% and 100%, wherein the humidity sensor arrangement ( 15 . 16 ) the humidity signal by means of a humidity sensor ( 16 ) between the drum ( 2 ) and the heat exchanger ( 25 ) is arranged. A method according to claim 14, characterized in that the predetermined range of relative humidity is between 80% and 100%, wherein the humidity sensor arrangement ( 15 . 16 ) the humidity signal by means of a humidity sensor ( 15 ) between the heat exchanger ( 25 ) and the heating ( 11 ) is arranged.