System and method for heating a sauna or steam room

Abstract

The invention relates to a system for heating a sauna or steam room, which system includes a first heater (10) for heating the air in the room (8), wherein the first heater (10) is configured with respect to its heating power to heat, by itself, the air in the room (8) to a temperature of 30-120 °C, preferably to a temperature of 50-110 °C, most preferably to a temperature of 70-100 °C, a second heater (20) for producing steam in the air of the room (8), wherein the second heater (20) includes a stone space (14) that is partially open in the room (8), which stone space (14) includes a thermal mass that is configured to be heated to a temperature of 200-700 °C, preferably 300-600 °C, in order to evaporate water dispensed into the stone space (14), or wherein the second heater (20) includes a water space for storing water, which water space is configured to be heated in order to form steam from the water stored in the water space, a temperature sensor (40) for measuring the temperature of the room (8), control means for controlling the power of the first heater (10) and of the second heater (20) as a function of a selected criterion based on measurement data of the temperature sensor (40), the first heater (10) and the second heater (20) are separate heaters that are independent of each other, and the first heater (10) is a storage heater with a storage capacity in relation to the volume of the room (8) of at least 200 Wh / m3, preferably at least 500 Wh / m3, most preferably at least 800 Wh / m3, and a heat output of at least 200 Wh / m3, preferably at least 400Wh / m3. The invention also relates to a corresponding method.

Description

[0001] SYSTEM AND METHOD FOR HEATING A SAUNA OR STEAM ROOM

[0002] The invention relates to a system for heating a sauna or steam room, which system includes

[0003] - a first heater for heating the air in the room, wherein the first heater is configured with respect to its heating power to heat, by itself, the air in the room to a temperature of 30- 120CC, preferably to a temperature of 50-110CC, most preferably to a temperature of 70-100 °C,

[0004] - a second heater for producing steam in the air of the room, wherein the second heater includes a stone space that is partially open in the room, which stone space includes a thermal mass that is configured to be heated to a temperature of 200- 700 °C, preferably 300-600 °C, in order to evaporate water dispensed into the stone space, or wherein the second heater includes a water space for storing water, which water space is configured to be heated in order to form steam from the water stored in the water space,

[0005] - a temperature sensor for measuring the temperature of the room,

[0006] - control means for controlling the power of the first heater and of the second heater as a function of a selected criterion based on measurement data of the temperature sensor.

[0007] The invention also relates to a corresponding method.

[0008] A good sauna can be defined as follows: the sauna room is at the temperature desired by the user, and the user is supplied with enough water vapour in the sauna room. In saunas according to the prior art, bringing this situation to pass most often poses a challenge.

[0009] A sauna according to the prior art, which here denotes what is known as a Finnish sauna, typically contains a single sauna stove that heats the room to a temperature for a sauna session, which can typically be between 60-120 “C according to user preference. The sauna stove includes a stone space, which is typically heated to a temperature of 200-700 °C. By periodically dispensing water onto hot stones or some other mass, such as a ceramic material, located in the stone space, the user can produce water vapour, i.e. sauna steam, in the room. A problem is that the continuous dispensing of water into the stone space of the sauna stove cools the stones and the power of the sauna stove is insufficient to maintain an adequate temperature in the stone space. This situation occurs in particular when the sauna room is at the target temperature and the sauna structures have heated up, so that the heating power of the sauna stove is typically limited in order to prevent the temperature in the sauna room from becoming unpleasantly high. The temperature of the stone space thus approaches the temperature of the sauna room, which is insufficient to produce steam. It is thus the experience of the user that the sauna stove does not produce enough water vapour, i.e. steam.

[0010] Similarly, a good steam room, i.e. what is known as a Turkish bath, can be defined as follows: the steam room is at the temperature desired by the user, and the user is promptly supplied with enough visible water vapour in the steam room. A steam room is typically heated to a temperature of 30-70 °C.

[0011] Steam rooms according to the prior art have a similar problem to saunas according to the prior art. It is difficult to achieve and maintain a situation in which the steam room is simultaneously at a pleasant temperature and has enough visible water vapour with a steam generator that heats the air in the steam room and produces the visible water vapour in the room.

[0012] Another practical problem is the inadequacy of a power supply for the power required by the sauna or steam room. With systems according to the prior art, heating a sauna or steam room from room temperature to a selected temperature for a sauna session and simultaneously heating a stone space or water space to a temperature required for steam production in a practical amount of time requires a large amount of momentary power, which is not necessarily always available. It thus takes an unreasonably long time to start up the sauna or steam room or it can even occur that the target temperatures are not entirely reached. Moreover, a heating of the sauna or steam room can take place at a time when the price of electricity is high. The peak power required to heat the sauna or steam room from room temperature to an operating temperature is thus expensive and creates a load on the power grid. The maintenance of temperature levels after the initial heating typically requires less power than the initial heating.

[0013] In particular the heating of a sauna from cold to hot requires a lot of power, because energy is being stored in the structures, the stones of the sauna stove and the air in the sauna room. Once the target temperature has been reached, significantly less power is needed, typically around 30% - 60% of the maximum power requirement, depending on the size, ventilation, and insulation of the sauna room as well as the maximum power of the sauna stove.

[0014] The size of modern saunas is constantly increasing, so that more heating power is needed to heat saunas than in the past. This leads to a high peak power in the initial phase of heating, so that it becomes necessary to equip the electrical structures with large conductors. With the green transition there is a desire to reduce peak powers.

[0015] The patent publication DE 3705715 Al discloses a sauna stove in which a stone space for producing steam in the sauna room and a separate air heating for heating the air in the sauna room are arranged in the same shared frame. The stone space and the air-heating channel are in thermal contact with each other, so that a sufficiently versatile control of the conditions in the sauna room and of the temperature of the stone space is not possible .

[0016] The object of the invention is to provide a system and a method in a sauna or steam room which allow the temperature of the room and the production of steam to be controlled in a more versatile manner than to date and independently of each other. The characteristic features of a system according to the invention are set out in the attached patent claim 1, while the characteristic features of a method according to the invention are set out in the attached patent claim 15.

[0017] A system according to the invention for heating a sauna or steam room includes:

[0018] - a first heater for heating the air in the room, wherein the first heater is configured with respect to its heating power to heat, by itself, the air in the room to a temperature of 30- 120 °C, preferably to a temperature of 50-110 °C, most preferably to a temperature of 70-100 °C,

[0019] - a second heater for producing steam in the air of the room, wherein the second heater includes a stone space that is partially open in the room, which stone space includes a thermal mass that is configured to be heated to a temperature of 200- 700°C, preferably 300-600°C, in order to evaporate water dispensed into the stone space, or wherein the second heater includes a water space for storing water, which water space is configured to be heated in order to form steam from the water stored in the water space,

[0020] - a temperature sensor for measuring the temperature of the room - control means for controlling the power of the first heater and of the second heater as a function of a selected criterion based on measurement data of the temperature sensor.

[0021] The first heater and the second heater are separate heaters that are independent of each other, and the first heater is a storage heater with a storage capacity in relation to the volume of the room of at least 200 Wh / m3, preferably at least 500 Wh / m3, most preferably at least 800W Wh / m3, and a heat output of at least 200 Wh / m3, preferably at least 400 Wh / m3.

[0022] In other words, in the system, the task of the first heater is to heat the air in the room and the task of the second heater is merely to ensure the existence of hot stones in the stone space of the sauna stove in the sauna or the heating of the water space of the steam generator in the steam room. Temperatures in the sauna or steam room can thus be controlled better than to date and independently of each other while an efficient steam production is ensured. In particular in a sauna, it is thus possible to influence the steam intensity in a manner desired by the user through the independent control of the temperature of the stone space vis-a-vis the temperature of the air in the room. Water dispensed into the stone space cools the stone space, so that this can be compensated by increasing the heat of the stone space of the second heater while simultaneously reducing the heating of the air in the room by the first heater.

[0023] The first heater is a storage heater with a storage capacity in relation to the volume of the room of preferably at least 200 Wh / m3, preferably at least 500 Wh / m3, most preferably at least 800 Wh / m3, and a heat output of at least 200 Wh / m3. The heat-retaining material can thus be charged with the energy needed to heat the sauna or steam room when the sauna or steam room is not in use, for example overnight. The peak power needed to heat the sauna or steam room can thus be reduced, as the stored heat can be released into the air of the room in the initial phase of heating. The first heater is preferably dimensioned to heat the air in the room from a temperature of 20 °C to a temperature of 80 °C in less than 60 minutes.

[0024] When a storage heater is used in the sauna or steam room, not only the energy stored in the same is essential, but a possible energy output rate or heating power of the thermal mass. Increasing the size of the storage heater makes it possible to store more energy; however, it must also be possible to transfer the stored energy quickly from the heat-retaining mass to the room, i.e. the heating power must be very high. A high heating power can be achieved by a very high temperature of the thermal mass, which can be significantly higher than the temperature of the stone space of the sauna stove. In addition, the heating power can be increased by a controlled flow of air through the thermal mass, wherein the flow of air is configured to be heated by the heat stored in the thermal mass. A maximum temperature of the storage heater that is higher than the stone space of the sauna stove is possible, for example by means of a closed structure of the storage heater, so that the storage heater does not radiate outwards and especially upwards like an open sauna stove. As the temperature of the stones in the sauna stove increases, the amount of radiation increases exponentially, and the temperature of the ceiling and of the surrounding walls becomes a problem. In practice, it is neither a good idea nor safe to heat stones in a sauna stove to temperatures above 700°C due to the increased radiant heat. The temperature of the mass that stores usable heat in the storage heater can consequently be higher than the temperature in the stone space of the sauna stove, although it can, on the other hand, also be lower. This is possible because the storage heater is used here only to heat the air in the room and not to produce steam. A possible closed structure also helps to render possible a wider range of usable temperatures of the storage heater. In other words, a sauna stove according to the prior art cannot be the first heater of the system, but the second heater can be a sauna stove according to the prior art.

[0025] Preferably, the first heater is configured to heat the air in the room while the second heater is configured to produce heat in the stone space or in the water space simultaneously. This allows the room to be heated efficiently and quickly. This also provides more options for the control of the temperatures, as the first heater is configured to manage the temperature of the room independently and the second heater is configured to manage the heating of the stone space or water space independently.

[0026] Preferably, the first heater includes a heat-retaining mass arranged in an enclosed and insulated space. In other words, the heat-retaining mass is protected in such a manner that water cannot come into contact with the heat-retaining mass. It is thus possible to control the energy stored in the first heater and the output of that energy. This also prevents or significantly reduces a heat transfer from the first heater by radiation, conduction and / or natural convection. Small heat losses from the first heater can be permitted and utilized to heat the room. As water is not dispensed into the first heater, it is possible to control the power of the heat output as well as the temperature of the thermal mass with precision.

[0027] Preferably, the first heater includes a heat-retaining mass, the temperature of which is configured to remain between 60- 800 °C, preferably between 100-800 °C. In other words, a larger variation in temperature is permitted for the heat-retaining mass of the first heater than for the stone space or water space of the second heater. The temperature of the thermal mass can be higher than the temperature of the stone space or water space of the second heater, so as to enable a high heat output. On the other hand, the temperature of the thermal mass can be lower than the temperature of the stone space or water space of the second heater, because the first heater is not needed to produce steam.

[0028] The first heater is preferably configured to discharge heat into the lower part of the room. It is thereby possible to reduce the temperature gradient of the air in the room. Even a low temperature of the thermal mass of the first heater is usable in this case, as temperatures in the lower part of the room can be around 45 °C during a sauna session.

[0029] Preferably, a melting point of the heat-retaining material of the first heater is at least 200° C. Preferably, the heatretaining material is something other than water. The heatretaining material can thus be kept in a solid state at the temperature required for heating the sauna or steam room.

[0030] Preferably, the heat-retaining mass includes stone and / or metal. Stone is an economical material with good heat-retaining properties that retains its solid state at the temperatures of the first heater. Metal, preferably steel, is readily mouldable, so that a thermal mass with a surface with a large surface area can be implemented that transfers heat to the air.

[0031] Preferably, the first heater includes a heat-retaining mass and a flow channel, and a fan and a valve arranged in the flow channel, wherein the flow of air flowing through the flow channel is configured to be heated by the heat stored in the heat-retaining mass. In other words, the first heater is preferably a flow-through heater. More specifically, except for the flow channel, the structure of the first heater is thus closed. The first heater can thus transfer heat energy effectively to the air in the room by forced convection. By means of the fan and the valve arranged in the flow channel, it is possible to control the heat output of the first heater.

[0032] Preferably at least 80%, most preferably at least 90%, of the heat output of the first heater is configured to be transferred to the air in the room by forced convection. This allows an effective control of the discharge of the heat of the first heater into the air of the room.

[0033] Preferably, the heat output rating of the first heater is greater than its charging capacity, preferably 5 times greater, most preferably 10 times greater. This allows the first heater to be charged using a low peak power while the first heater can still momentarily provide a high power output for the heating of the room.

[0034] Preferably, the first heater has a storage coefficient of 0.2- 2. The storage coefficient here denotes the ratio between the heat output rating and the storage capacity of the first heater. This allows a sufficient amount of energy to be transferred from the first heater to the room quickly enough.

[0035] The first heater can be arranged outside the room. For example, the first heater can be arranged outside the room in such a manner that the warm air produced by the first heater is conducted into the room through a pipe. The first heater thus does not take up any space in the sauna room.

[0036] Alternatively, the first heater can be arranged inside the room, for example under seats in the room. Any energy losses of the first heater can thus be utilized to heat the room. The system can include at least two first heaters, which first heaters are independent of each other. This provides more control options for the temperature of the air in the room and the energy consumption of the system. It is thus possible to use a plurality of separate low-power first heaters to heat a large room, so that the total power of the system is increased. It is also possible to use only a single sufficiently powerful first heater.

[0037] Preferably, the first heater and / or the second heater is configured to be heated by resistors or by burning wood or gas or a combustible liquid, such as oil, or by friction generated by an electrically operated turbine. The temperature required by the sauna or steam room can thus be produced in an energyefficient manner.

[0038] The stone space of the second heater can be partially enclosed in such a manner that the second heater can comprise a frame that covers at least 50%, preferably at least 80%, of the stone space. In other words, at most 50 %, preferably at most 20 %, of the surface area of the edges of the stone space is thus visible from outside the sauna stove. This makes it easier to maintain a desired temperature in the stone space.

[0039] The system can include a cover for insulating the stone space of the second heater in order to store heat in the stone space. It is thus possible to store heat in the stone space when the sauna is not in use, and the stone space can be maintained at a selected temperature, so that the sauna can be started up faster .

[0040] The second heater can include a temperature sensor that measures the temperature of the stone space or water space, wherein the system is configured to control the heating of the stone space or water space of the second heater based on measurement data of said temperature sensor. It is thus possible to ensure that the stone space or water space remains at the target temperature .

[0041] Preferably, the system is configured to maintain a temperature selected by the user in the stone space or water space. This makes it possible to influence the steam production, i.e. the intensity of the sauna steam, of the stone space or the steam production of the water space of the second heater independently of the temperature of the room.

[0042] Preferably, the control means is configured to give a first control command to the first heater to heat the air in the room to a target temperature, and the control means is configured to give a second control command to the second heater to heat the stone space or water space to a target temperature. The system can thus be configured to control the temperature of the air in the room and the temperature of the stone space or water space independently of each other.

[0043] In cases where the second heater of the system is a sauna stove, the sauna stove can include a frame, a stone space that includes a thermal mass, which is capable of being heated to a temperature of 200-700 °C and of evaporating water dispensed into the stone space, and a flow channel with a first opening outside the frame and a second opening inside the frame in the stone space. The sauna stove can further include a valve, which valve is configured to limit the flow of a fluid in the flow channel, and which valve is configured to open under the action of the pressure of water evaporating in the stone space, which allows water vapour to flow in the flow channel from the second opening to the first opening and air from outside the frame to flow from the first opening to the second opening, through the stone space and back outside the frame, and which valve is configured to close automatically. The flow channel of the sauna stove can thus be configured to open synchronously in connection with the throwing of water into the hot stone space, whereby the intensity of the sauna steam can be increased by controlling the flow of air through the stone space at the moment that water is thrown into the stone space.

[0044] The system can include a sensor for detecting a physical phenomenon caused in the sauna room by water evaporating in the stone space and software means for identifying the physical phenomenon. A physical phenomenon caused by the throwing of water into the hot stone space can be, for example, a change in air humidity in the sauna room, or a change in the temperature of the air in the sauna room, or a change in the optical properties of the air, or a sound. The sensor can be any sensor according to the prior art capable of producing a detectable signal from a physical phenomenon caused by the creation of sauna steam due to the throwing of water into the hot stone space. The selected sensor can be configured to monitor the sauna room for the complete duration of a sauna session. In this case, the system must include software means for identifying a change produced by sauna steam in the continuously generated measurement signal of the sensor. Software means is broadly defined here as any computer program that includes software code means configured to identify a change in the measurement signal of the sensor caused by the creation of steam due to the throwing of water into the hot stone space when the computer program is executed on a computer. The software means can be arranged, for example, in a control unit of the sauna stove or in a separate computer. Data relating to steam creation due to the throwing of water into the hot stone space that is captured by the system can be utilized for a selected application, such as for controlling functions of the sauna stove, or for a lifestyle application by providing the user of the sauna with data relating to the sauna session. In general, the characteristic profile for each identifiable phenomenon can either be learned or defined deterministically. In cases where the second heater includes a valve for controlling the flow of air, the valve can be configured to open and close based on data received from the sensor.

[0045] In a method according to the invention for heating a sauna or steam room:

[0046] - the air in the room is heated by a first heater, wherein the first heater is configured with respect to its heating power to heat, by itself, the air in the room to a temperature of 30- 120 °C, preferably to a temperature of 50-110 °C, most preferably to a temperature of 70-100 °C,

[0047] - steam is produced in the air of the room by a second heater, wherein the second heater includes a stone space that is partially open in the room, which stone space includes a thermal mass that is configured to be heated to a temperature of 200- 700 °C, preferably 300-600 °C, in order to evaporate water dispensed into the stone space, or wherein the second heater includes a water space for storing water, which water space is configured to be heated in order to form steam from the water stored in the water space,

[0048] - the temperature of the room is measured by a temperature sensor,

[0049] - the heating power of the first heater and of the second heater is controlled by control means as a function of a selected criterion based on measurement data of the temperature sensor. The first heater is controlled independently of the second heater, and the first heater is a storage heater with a storage capacity in relation to the volume of the room of at least 200 Wh / m3, preferably at least 500 Wh / m3, most preferably at least 800 Wh / m3, and a heat output of at least 200 Wh / m3, preferably at least 400 Wh / m3, wherein the first heater is charged with heat prior to a sauna session.

[0050] This allows a control of the temperatures of a sauna or steam room that is more versatile than to date and makes it possible to ensure an efficient steam production. The temperatures of the air in the room and of the stone space or water space can be controlled independently of each other and the peak power caused by heating can be reduced.

[0051] Preferably, electrical energy is supplied to the first heater in order to store heat, and electrical energy is supplied to the second heater in order to produce heat in the stone space or water space, and the electrical energy is supplied in increments in such a manner that a momentary electrical power is at most 70%, preferably at most 50%, of the total supply capacity of all the heaters. In other words, the charging of the first heater and the supplying of the second heater with energy are preferably never carried out simultaneously at maximum power, but rather a power that is lower than maximum power is always supplied to at least one of the heaters. This prevents a high peak power. For example, the first heater and the second heater can be configured to be controlled in increments, for example at a moment of one' s choosing, either at 100 % power, or at 50 % power, or at 0 % power. In other words, the first heater is not charged at maximum power when the power supply of the second heater is on. The first heater can, however, be charged at a low power even when the second heater is on, which can ensure a sufficient amount of heat in cases where the sauna or steam room is in use for a long time.

[0052] The heat stored in the first heater can be discharged into the air of the room at a power that is higher than the power at which the first heater is charged with heat, preferably at a power 5 times higher, most preferably at a power 10 times higher. It is thus possible to heat the sauna or steam room to the target temperature quickly with a low peak power.

[0053] Preferably, the energy needed to heat the room is charged into the first heater when the sauna or steam room is not in use, preferably at a power lower than the maximum power, and the energy stored in the first heater is supplied to the room during the heating of the room. This makes it possible to reduce the peak power needed to heat the sauna or steam room, as the stored heat can be released into the air in the room in the initial phase of heating.

[0054] Preferably, in the initial phase of the heating of the room, the air in the room is heated by the first heater and the stone space or water space is heated by the second heater, and, when the temperature of the room exceeds a selected first temperature, the energy supply to the first heater is stopped while the second heater continues to be supplied with energy in order to maintain the temperature of the stone space or water space at a target temperature.

[0055] Preferably, a first limit value is set for the temperature of the room, and, when the temperature of the room is below the selected first limit value, heat is produced in the room simultaneously by the first heater and by the second heater by means of which the stone space or water space is heated. The room can thus be placed quickly in a ready-to-use state by using the first heater and the second heater simultaneously for a selected heating.

[0056] Preferably, when the temperature of the room exceeds a selected second temperature, the energy supplied to the second heater is limited; when the temperature of the room falls below the selected first temperature, heat is produced in the room with the first heater; and, when the temperature of the room is between the selected first temperature and the selected second temperature, the energy supply to the first heater is stopped while energy continues to be supplied to the stone space or water space of the second heater in order to maintain the stone space or water space at the selected temperature. This allows the temperatures of the room and of the stone space or water space to be controlled with precision.

[0057] Preferably, a first limit value and a second limit value are set for the temperature of the sauna room, wherein the first limit value is lower than the second limit value, and

[0058] - when the temperature of the room is below the selected first limit value, heat is produced in the room by the first heater and the second heater,

[0059] - when the temperature of the room is above the selected first limit value and below the selected second limit value, heat is produced in the room by the second heater only, wherein the stone space or water space of the second heater is supplied with energy in order to maintain the stone space or water space at a selected temperature,

[0060] - when the temperature of the room is above the selected second limit value, the energy supplied to the second heater is limited .

[0061] More specifically, when the temperature of the room is above the selected first limit value and / or above the selected second limit value, the first heater does not heat the room. This allows the temperatures of the room and of the stone space or water space to be controlled independently of each other, whereby a temperature that is pleasant to the user and a suitable steam production are achieved in the room. Preferably, a target temperature is set for the stone space or water space, which the second heater is configured to maintain when the temperature in the room is below the selected second limit value. This ensures a sufficient steam production throughout the sauna session. The power of the second heater is only limited when the temperature of the room becomes too high for safety reasons or when the temperature of the room becomes unpleasantly high for the user.

[0062] Preferably, during use of the sauna, the temperature of the thermal mass of the first heater is kept between 60-800 °C, preferably between 100-800 °C, and the temperature of the stone space of the second heater is kept between 200-700 °C, preferably between 300-600 °C. The air of the room can thus be heated with the stored heat of the first heater while steam can be produced in the room with the second heater by dispensing water into the stone space.

[0063] The invention is described in detail in the following with reference to the attached drawings illustrating embodiments of the invention, wherein

[0064] Figure 1 shows a system according to the invention,

[0065] Figure 2 shows the supply of power in a system according to the invention as a function of time,

[0066] Figure 3 shows air temperature as a function of time in a system according to the invention.

[0067] Figure 1 shows a system according to the invention for heating a sauna, which system includes

[0068] - a first heater 10 for heating the air in the room 8, wherein the first heater 10 is configured with respect to its heating power to heat, by itself, the air in the room 8 to a temperature of 30-120°C, preferably to a temperature of 50-110°C, most preferably to a temperature of 70-100°C,

[0069] - a second heater 20 for producing steam in the air of the room 8, wherein the second heater 20 includes a stone space 14 that is partially open in the room 8, which stone space 14 includes a thermal mass that is configured to be heated to a temperature of 200-700°C, preferably 300-600°C, in order to evaporate water dispensed into the stone space 14,

[0070] - a temperature sensor 40 for measuring the temperature of the room 8,

[0071] - control means for controlling the power of the first heater 10 and of the second heater 20 as a function of a selected criterion based on measurement data of the temperature sensor 40.

[0072] The first heater 10 and the second heater 20 are separate heaters that are independent of each other, and the first heater 10 is a storage heater with a storage capacity in relation to the volume of the room 8 of at least 200 Wh / m3, preferably at least 500 Wh / m3, most preferably at least 800 Wh / m3, and a heat output of at least 200 Wh / m3, preferably at least 400 Wh / m3.

[0073] The system according to the invention shown in Figure 1 is thus what is known as a Finnish sauna, in which the second heater 20 is a sauna stove that includes a stone space 14, which includes stones 15 as the heat-retaining mass here. The sauna stove can further include a temperature sensor 18 that measures the temperature of the stone space 14, wherein the heating of the stone space 14 can be controlled based on measurement data of the temperature sensor 18. The sauna stove can be any sauna stove according to the prior art. When the system is in operation, the user dispenses water into the second heater 20, but not into the first heater 10, which is closed in such a manner that water cannot come into contact with the hot part of the first heater 10. The stone space 14 of the second heater 20 can be partially enclosed in such a manner that the second heater 20 includes a frame 12 which covers at least 50%, preferably at least 80%, of the stone space 14. The stone space 14 is thus insulated from the air in the room 8, so that the temperature of the stone space 14 can be controlled with precision and it can be ensured that the stone space 14 stays warm during the sauna session in order to enable an effective steam production. Significant amounts of heat are thus not transferred from the stone space 14 to the air in the room 8, so that the heating of the air is mainly implemented by the first heater 10. By improving the thermal insulation of the stone space 14, the dependence of the air temperature in the room 8 on the temperature of the stone space 14 can be reduced, so that it becomes possible to influence the steam intensity more by regulating the temperature of the stone space 14 without affecting the temperature of the air in the room 8 as much.

[0074] The system includes two first heaters 10 here, which are arranged under the benches 30 in the sauna. The first heater 10 here is a flow-through storage heater. The first heater 10 includes a heat-retaining mass and a flow channel, and a fan and valve arranged in the flow channel, wherein the flow of air flowing through the flow channel is configured to be heated by the heat stored in the heat-retaining mass. The structure of the first heater 10 is closed and insulated in such a manner that heat is transferred from the thermal mass to the room 8 mainly by forced convection produced by the fan.

[0075] For example, the first heater can be a Dimplex Quantum RF HHR Storage Heater, more specifically the model number QM150RF, which is configured with the necessary control-technical modifications to heat the room 8 to a selected temperature. This heater has a heat-retaining mass of iron-rich stone, a storage capacity of 23100 Wh, and a heat output rating with the factory settings of 1500 W. However, the heat output rating can be significantly increased up to a value of 6000 W or even higher with the necessary modifications. This heater can function alone as the first heater in a room of approximately 40 m3or less. In larger rooms, two or more heaters are used.

[0076] Alternatively, the first heater can be located outside the room, so that the warm air produced by the first heater 10 is conveyed into the room 8, for example, via a pipe.

[0077] The temperature of the room 8 is monitored by a temperature sensor 40 arranged on an upper part of a wall in the room 8. The measurement data of the temperature sensor 40 is transmitted to the control means, which is arranged here in a control unit 60 of the system. The power supply and the heat production of the first heater 10 and of the second heater 20 are controlled based on the measurement data of the temperature sensor 40. Alternatively, the temperature sensor 40 can be arranged elsewhere in the room or integrated into the first heater 10 or the second heater 20. Determining the absolute temperature of the room 8 is not in itself crucial, but rather the temperature sensor measures a selected temperature which is relatively indicative of the temperature of the air in the room 8 and which can be used to control the operation of the system.

[0078] An alternative embodiment can correspond to the embodiment shown in Figure 1 with the exception that the second heater 20 includes a water space for storing water, which water space is configured to be heated in order to form steam. In this case, the steam room is what is known as a Turkish bath in which the second heater 20 is a steam generator, which can be any steam generator according to the prior art. Figure 2 shows the effect of a chargeable first heater 10 on the supply of power in a system according to the invention as a function of time. The solid line represents the power consumption of a system according to the prior art. During a time tl, the room 8 is heated by supplying the heater at maximum power so as to heat the air in the room 8 within a practical amount of time while the stone space 14 or water space is simultaneously heated. Once the air in the room 8a reaches the selected temperature, the heater can be operated at a lower power for a time t2, which is sufficient to maintain the temperature of the air in the room 8 at the selected level, but the problem of a poor steam production described in the foregoing can then occur.

[0079] The dashed line in Figure 2 represents the change in the total power consumption of the system brought about by the system according to the invention. Before the sauna or steam room is started up, at a time tO, the heat-retaining material of the first heater 10 can be charged with heat. During the time tl, the heat stored in the thermal material of the first heater 10 is discharged into the air of the room 8, so that it is not necessary to supply energy to the first heater 10 over the time tl. During the time tl, energy is only supplied to the second heater 20 in order to heat the stone space 14 or water space. This makes it possible to reduce the maximum power consumption of the system. The power consumption shown in Figure 2 is illustrative and the actual power consumption can differ. What is essential, however, is that, preferably, electrical energy is supplied to the first heater 10 in order to store heat and electrical energy is supplied to the second heater 20 in order to produce heat in the stone space 14 or water space, and that electrical energy is supplied in increments in such a manner that a momentary electrical power is at most 70%, preferably at most 50%, of the total supply capacity of all the heaters. In Figure 2, the lower power supply is 50% of the maximum, but it can be, for example, anywhere between 30% and 60%.

[0080] Figure 3 depicts an automatically controlled maintenance of a target temperature in a room 8. A first temperature Tl, for example 80 °C, and a second temperature T2, for example 83 °C, are set with the control means of the system, and the system is configured to maintain the temperature of the room 8 between these temperatures by controlling the heat production of the first heater 10 and of the second heater 20 based on measurement data of the temperature sensor 40 that measures the temperature of the room 8.

[0081] In a step 101, in an initial phase of the heating of the room 8, the air in the room 8 is heated by the first heater 10 and the stone space 14 or water space is heated by the second heater 20. Preferably, energy is not supplied at full power simultaneously to both the first heater 10 and to the second heater 20. Instead, the first heater 10 or the second heater 20 can include stored heat that is released in step 101.

[0082] In a step 102, when the temperature of the room 8 exceeds the selected first temperature Tl, the energy supply to the first heater 10 and / or the discharge of energy from the first heater 10 is stopped while the second heater 20 continues to be supplied with energy in order to keep the stone space 14 or water space at the selected temperature. The temperature of the room 8 is thus maintained at the selected level while it is simultaneously ensured that the temperature of the stone space 14 or water space is kept at a selected level in order to ensure an efficient steam production. In a step 103, when the temperature in the room 8 exceeds the selected second temperature T2, the energy supplied to the second heater 20 is limited. In other words, in cases where stopping the heat production of the first heater 10 in step 102 is insufficient to stop the temperature of the room 8 from rising, the power of the second heater 20 is also interrupted or limited. However, the limitation of the power of the second heater 20 is typically of such a short duration that it does not significantly affect the temperature of the stone space 14 or water space.

[0083] In a step 104, when the temperature of the room 8 falls below the selected first temperature Tl, heat is produced in the room 8 by the first heater 10. In other words, once the room 8 has been heated, the heat produced in the room 8 by the second heater 20 can be sufficient to maintain the selected temperature level in the room 8. In cases where it is insufficient, however, the first heater 10 is configured to produce heat momentarily in the air of the room 8. The impact of the first heater 10 is typically most significant in the initial phase of heating when the room 8 is heated from cold to hot, during which time a large amount of heating power is typically needed to store heat in the air and in the structures of the room 8.

[0084] In a step 105, when the temperature of the room 8 is between the selected first temperature Tl and the selected second temperature T2, the energy supply to the first heater 10 is stopped and energy is supplied to the stone space 14 or water space of the second heater 20 in order to maintain the stone space 14 or water space at a selected temperature. The heat produced by the second heater 20 can thus be sufficient to maintain the temperature of the air in the room 8 at a selected level . Once the room 8 has been heated, changes in the temperature of the room 8 during use can be caused, for example, by the opening and closing of the door 9 of the room 8 or by dispensing water into the stone space 14 so that, when necessary, the heat production of the first heater 10 and of the second heater 20 in the room 8 is controlled as described in the foregoing.

[0085] The stone space 14 or water space can include its own separate temperature sensor 18, and the temperature of the stone space 14 or water space is maintained at the target temperature based on measurement data of this temperature sensor 18 by controlling the heat production of the second heater 20. Preferably, a selected target temperature for the stone space 14 or water space can be set with the control means. The user can thus control a magnitude of steam production. In the case of a sauna, it is consequently possible to influence the steam intensity and thus the sauna steam effect experienced by the user. For example, when the stone space 14 is hotter, steam formation is more efficient and the temperature of the formed steam is higher, so that the user experiences a more potent steam effect.

Claims

CLAIMS1. A system for heating a sauna or steam room, which system includes- a first heater (10) for heating the air in the room (8) , wherein the first heater (10) is configured with respect to its heating power to heat, by itself, the air in the room (8) to a temperature of 30-120 °C, preferably to a temperature of 50-110 °C, most preferably to a temperature of 70-100 °C,- a second heater (20) for producing steam in the air of the room (8) , wherein the second heater (20) includes a stone space (14) that is partially open in the room (8) , which stone space (14) includes a thermal mass that is configured to be heated to a temperature of 200-700 °C, preferably 300-600 °C, in order to evaporate water dispensed into the stone space (14) , or wherein the second heater (20) includes a water space for storing water, which water space is configured to be heated in order to form steam from the water stored in the water space,- a temperature sensor (40) for measuring the temperature in the room ( 8 ) ,- control means for controlling the power of the first heater (10) and of the second heater (20) as a function of a selected criterion based on measurement data of the temperature sensor (40) , characterized in that- the first heater (10) and the second heater (20) are separate heaters that are independent of each other, and- the first heater (10) is a storage heater with a storage capacity in relation to the volume of the room (8) of at least 200 Wh / m3, preferably at least 500 Wh / m3, most preferably at least 800 Wh / m3, and a heat output of at least 200 Wh / m3, preferably at least 400 Wh / m3.

2. The system according to claim 1, characterized in that said first heater (10) is configured to heat the air in the room (8) while said second heater (20) is configured to produce heat in the stone space (14) or in the water space simultaneously .

3. The system according to claim 1 or 2, characterized in that said first heater (10) includes a heat-retaining mass arranged in an enclosed and insulated space.

4. The system according to any one of claims 1 - 3, characterized in that said first heater (10) includes a heatretaining mass, the temperature of which is configured to remain between 60-800 °C, preferably between 100-800 °C.

5. The system according to any one of claims 1 - 5, characterized in that said first heater (10) includes a heatretaining mass with a melting point of at least 200cC.

6. The system according to claim 5, characterized in that the heat-retaining mass includes stone and / or metal.

7. The system according to any one of claims 1 - 6, characterized in that said first heater (10) includes a heatretaining mass and a flow channel, and a fan and a valve arranged in the flow channel, wherein the flow of air flowing through the flow channel is configured to be heated by the heat stored in the heat-retaining mass.

8. The system according to claim 7, characterized in that at least 80%, preferably at least 90%, of the heat output of said first heater (10) is configured to be transferred to the air of the room (8) by forced convection.

9. The system according to any one of claims 1 - 8, characterized in that the heat output rating of said first heater (10) is greater than its charging capacity, preferably 5 times greater, most preferably 10 times greater.

10. The system according to any one of claims 1 - 9, characterized in that said first heater (10) is arranged outside the room (8) .

11. The system according to any one of claims 1 - 10, characterized in that the system includes at least two first heaters (10) , which first heaters (10) are independent of each other .

12. The system according to any one of claims 1 - 11, characterized in that said second heater (20) includes a temperature sensor (18) that measures the temperature of the stone space (14) or water space, wherein the system is configured to control the heating of the stone space (14) or water space of said second heater (20) based on measurement data of said temperature sensor (18) .

13. The system according to any one of claims 1 - 12, characterized in that the system is configured to maintain a temperature selected by the user in the stone space (14) or water space.

14. The system according to any one of claims 1 - 13, characterized in that said control means is configured to give a first control command to said first heater (10) to heat the air in the room (8) to a target temperature, and the control means is configured to give a second control command to said second heater (20) to heat the stone space (14) or water space to a target temperature.

15. A method for heating a sauna or steam room, wherein in the method- the air in the room (8) is heated by a first heater (10) , wherein the first heater (10) is configured with respect to its heating power to heat, by itself, the air in the room (8) to a temperature of 30-120 °C, preferably to a temperature of 50- 110 °C, most preferably to a temperature of 70-100 °C,- steam is produced in the air of the room (8) by a second heater (20) , wherein the second heater (20) includes a stone space (14) that is partially open in the room (8) , which stone space (14) includes a thermal mass that is configured to be heated to a temperature of 200-700 °C, preferably 300-600 °C, in order to evaporate water dispensed into the stone space (14) , or wherein the second heater (20) includes a water space for storing water, which water space is configured to be heated in order to form steam from the water stored in the water space,- the temperature of the room (8) is measured by a temperature sensor (40) ,- the heating power of the first heater (10) and of the second heater (20) is controlled by control means as a function of a selected criterion based on measurement data of the temperature sensor (40) , characterized in that- the first heater (10) is controlled independently of the second heater (20) , and- the first heater (10) is a storage heater with a storage capacity in relation to the volume of the room (8) of at least 200 Wh / m3, preferably at least 500 Wh / m3, most preferably at least 800 Wh / m3, and a heat output of at least 200 Wh / m3, preferably at least 400 Wh / m3, wherein the first heater (10) is charged with heat prior to a sauna session.

16. The method according to claim 15, characterized in that electrical energy is supplied to said first heater (10) in order to store heat, and electrical energy is supplied to said second heater (20) in order to produce heat in the stone space (14) or water space, and the electrical energy is supplied in increments in such a manner that a momentary electrical power is at most 70%, preferably at most 50%, of the total supply capacity of all the heaters.

17. The method according to claim 15 or 16, characterized in that the heat stored in the first heater (10) is discharged into the air of the room (8) at a power that is higher than the power at which the first heater (10) is charged with heat, preferably at a power 5 times higher, most preferably at a power 10 times higher.

18. The method according to any one of claims 15 - 17, characterized in that the energy needed to heat the room (8) is charged into said first heater (10) when the sauna or steam room is not in use, preferably at a power lower than the maximum power, and the energy stored in the first heater (10) is supplied to the room (8) during the heating of the room (8) .

19. The method according to any one of claims 15 - 18, characterized in that a first limit value (Tl) is set for the temperature of the room (8) , and, when the temperature of the room (8) is below the selected first limit value (Tl) , heat is produced in the room (8) simultaneously by said first heater (10) and by said second heater (20) by means of which the stone space (14) or water space is heated.

20. The method according to any one of claims 15 - 19, characterized in that a first limit value (Tl) and a second limit value (T2) are set for the temperature of the sauna room(8) , wherein the first limit value (Tl) is lower than the second limit value (T2) , and- when the temperature of the room (8) is below the selected first limit value (Tl) , heat is produced in the room (8) by the first heater (10) and the second heater (20) ,- when the temperature in the room (8) is above the selected first limit value (Tl) and below the selected second limit value (T2) , heat is produced in the room (8) by said second heater (20) only, wherein the stone space (14) or water space of said second heater (20) is supplied with energy in order to maintain the stone space (14) or water space at a selected temperature ,- when the temperature in the room (8) is above the selected second limit value (T2) , the energy supplied to said second heater (20) is limited.

21. The method according to claim 20, characterized in that a target temperature is set for the stone space (14) or water space, which the second heater (20) is configured to maintain when the temperature of the room (8) is below the selected second limit value (T2) .

22. The method according to any one of claims 15 - 21, characterized in that, during use of the sauna, the temperature of the thermal mass of said first heater (10) is kept between 60 - 800 °C, preferably between 100 - 800 °C, and the temperature of the stone space (14) of said second heater (20) is kept between 200 - 700 °C, preferably between 300 - 600 °C.

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