Modular heating system for hot tub
Patent Information
- Application Number
- PCT/NO2026/050022
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2025-03-14
- Filing Date
- 2026-03-12
- Publication Date
- 2026-09-17
Smart Images
Figure NO2026050022_17092026_PF_FP_ABST
Abstract
Description
[0001] MODULAR HEATING SYSTEM FOR HOT TUB
[0002] FIELD OF INVENTION
[0003] The invention relates to a modular heating system for a hot tub or a pool. The invention further relates to a hot tub heating system and a method for heating water in a hot tub or a pool.
[0004] BACKGROUND OF THE INVENTION
[0005] The marked for hot tubs and pools has increased steadily over several years. Heating the water in a hot tub is usually done by electrical heating. With the global increase of electricity prices, it has become more expensive to heat a hot tub, and to keep the heating on. A result of the increased cost is therefore reduced use of hot tubs or pools, and even temporarily closures to avoid high costs.
[0006] Electrical heating of water in a hot tub usually comprises heating with electric heating elements with a power of between 1.5 kW to 4 kW, usually around 3 kW. This is well suited for small hot tubs or pools, but for larger hot tubs, the time it takes to heat the water to a comfortable temperature is quite considerable when using this technology. For example it would take approximately 14 hours to heat a 1200 litre hot tub from 8.5°C to 38°C using a standard 3 kW electric heating element.
[0007] The long heating time and the associated cost is especially problematic in cases where the hot tub is put out of service between every use, or where frequent change of water is desirable, or even required by law. The last case may for example be holiday rental homes where a hot tub or a pool is provided.
[0008] The increased cost of electricity and the long heating times lead to higher electricity bills
[0009] P31634PC00 description and claims -for filingand reduced usability of the hot tubs. Installing more electrical heating elements is associated with extra costs in the form of purchasing of the elements and their instalment.
[0010] Other alternatives for heating water such as heating by combustion heaters, central heating systems or heat pumps are associated with complex and expensive installations. Heat loss when removing the water from the hot tub for heating is also a problem associated with these type of heating systems.
[0011] WO2022065937 describes a water heater comprising a burner and a humidifier unit that generates water vapor and provides the water vapor together with the air to the burner.
[0012] EP1030123B1 describes a combined cycle heating plant comprising a burner that acts upon a heat exchanger, and a further heat exchanger that acts upon the exhaust gases from the fuel cell.
[0013] Various heat exchanger arrangements in gas water heaters are shown in CN 115451577 A, US 10309686 B2, and US 10627133 B2.
[0014] SUMMARY OF THE INVENTION
[0015] The invention has for its object to remedy or to reduce at least one of the drawbacks of the prior art, or at least provide a useful alternative to prior art.
[0016] The object is achieved through features, which are specified in the description below and in the claims that follow.
[0017] The invention is defined by the independent patent claims. The dependent claims define advantageous embodiments of the invention.
[0018] In a first aspect, the invention relates to a modular heating system for a hot tub, the modular heating system comprising:
[0019] - a combustion heater comprising:
[0020] - an air inlet and an outlet for exhaust gases;
[0021] - a fuel inlet; and
[0022] P31634PC00 P31634PC00 description and claims -for filing- a working fluid inlet and a working fluid outlet, the combustion heater being configured for heating a working fluid;
[0023] - a water inlet and a water outlet in fluid communication with the water inlet, such that a water loop between the water inlet and the water outlet is formed, the water inlet being configured for receiving water from the hot tub and the water outlet being configured for emitting water to the hot tub;
[0024] - a working fluid pump for circulating a working fluid between the working fluid outlet and the working fluid inlet in a working fluid loop;
[0025] - a first heat exchanger connected to the working fluid loop and to the water loop, such that the water is heated up by the working fluid in operational use; and
[0026] - a second heat exchanger connected to the outlet for exhaust gases of the combustion heater and connected to one of the working fluid loop or the water loop such that one of the working fluid or the water is heated by exhaust gases from the combustion heater in operational use;
[0027] wherein the combustion heater, the first heat exchanger, the second heat exchanger, and the working fluid pump are provided within a housing.
[0028] The effect of the features of the first aspect of the invention are as follows:
[0029] First of all, the combustion heater provides a more effective and faster heating of water in a hot tub or pool. The combustion heater may have an effect of between 2 and 5 kW or between 2 kW and 10 kW, or above 10 kW, depending on desired capacity. The modular heating system may therefore be particularly suited for fast heating of large volumes of water.
[0030] Secondly, heating the water indirectly, by a working fluid, instead of directly in the combustion heater, decreases the risk of leakages directly in the combustion heater. Water from the hot tub may contain calcium which may create deposits within the combustion heater if heated directly in the combustion heater. By instead heating a working fluid, calcium deposits may be avoided. Furthermore, water from the hot tub may typically contain chlorine compounds and bromine compounds for hygiene reasons, which may lead to corrosion of metals in contact with the water. Heating a working fluid in the
[0031] P31634PC00 P31634PC00 description and claims -for filingcombustion heater may avoid corrosion of parts of the combustion heater by water. Also, by separating the water loop from the combustion heater, the combustion heater may be dismounted from the modular heating system without having to empty the water loop.
[0032] The working fluid pump circulates the heated working fluid from the combustion heater and into the first heat exchanger. There, the water in the water loop is heated by the heated working fluid. The colder working fluid that exits the first heat exchanger is circulated back into the combustion heater for reheating.
[0033] The second heat exchanger draws additional heat from the exhaust gases from the combustion heater and may heat up the water in the water loop or the working fluid in the working fluid loop. This may reduce heat loss of the modular heating system and increase the total efficiency of the modular heating system.
[0034] Moreover, providing the combustion heater, the first heat exchanger, the second heat exchanger, and the working fluid pump within a common housing may greatly simplify the instalment of the modular heating system with the hot tub or the pool. Fewer external connections between the hot tub and the modular heating system, such as the water inlet and water outlet, may lower the chance of errors during instalment. The water inlet and water outlet may be easily connected to the hot tub or pool with standard pipes. The modular heating system may be particularly suitable for retrofitting with already produced hot tubs and pools, with minimal intervention in the hot tubs and pools.
[0035] Throughout the description the word "hot tub" is used. It must be understood that the invention is also suitable to use with other type of reservoirs of water made for swimming or bathing, such as pools, spa baths, massage baths, whirlpools, counter-current baths, etc.
[0036] In an embodiment of the invention the second heat exchanger may be connected to the water loop such that the water is heated up by exhaust gases from the combustion heater in operational use. The water in the water loop is thereby heated in the two heat exchangers, which may decrease the time it takes to heat the water in the hot tub or pool.
[0037] The first and the second heat exchangers may be connected to the water loop in series.
[0038] P31634PC00 P31634PC00 description and claims -for filingThe first and the second heat exchangers may preferably be connected to the water loop in series such that the water in the water loop is first heated in the second heat exchanger and then in the first heat exchanger in operational use. By first passing the water in the water loop through the second heat exchanger, the exhaust gases are cooled more down than if the water passes through the first heat exchanger first.
[0039] Alternatively, the water loop may be divided into a first and a second water sub loop, the first water sub loop being connected to the first heat exchanger and the second water sub loop being connected to the second heat exchanger, such that the first and the second heat exchangers may be connected to the water loop in parallel.
[0040] Preferably, the two water sub loops may be recoupled to a single water loop upstream the water outlet.
[0041] In an embodiment of the invention, the modular heating system may further comprise a water pump for circulating water from the water inlet to the water outlet.
[0042] This may be advantageous for using with hot tubs or pools that do not already have an internal pump for circulating water. The water pump may be provided within the housing, which may reduce heat loss and simplify the installation of the modular heating system to a hot tub or pool.
[0043] In an embodiment of the invention the modular heating system may comprise a fuel pump in connection with the fuel inlet for pumping fuel into the combustion heater.
[0044] The embodiments previously described, could function with an external fuel reservoir system that comprises a fuel pump. Then the external fuel reservoir system could be connected to the fuel inlet of the modular heating system for providing fuel to the combustion heater using the fuel pump of the external fuel reservoir system. In this embodiment, the provided fuel pump of the modular heating system makes it easier for the user to simply connect the fuel pump with an external fuel tank.
[0045] The fuel pump may be provided within the housing, which may result in a more compact modular heating system.
[0046] P31634PC00 P31634PC00 description and claims -for filingThe modular heating system may further comprise a fuel reservoir within the housing, the fuel reservoir being in connection with the fuel pump.
[0047] The integrated fuel reservoir may be an easy solution for the user because there may be no need of an external fuel tank. The integrated fuel reservoir may be dimensioned to ensure operation of the combustion heater for a desired number of hours.
[0048] In an embodiment of the invention, the first heat exchanger may comprise an expansion tank, to compensate for volume changes of the working fluid due to temperature changes. The expansion tank may be easily accessible inside the housing such that a user may easily inspect the expansion tank and replenish the working fluid if needed.
[0049] The first heat exchanger and / or the second heat exchanger may further comprise a galvanic anode. The galvanic anode may decrease the rate of corrosion of the first and / or second heat exchanger.
[0050] In an embodiment of the invention, the modular heating system may further comprise a control unit for controlling the combustion heater.
[0051] The control unit may be configured for controlling the working fluid pump and the fuel pump.
[0052] In an embodiment of the invention the combustion heater may comprise a combustion heater heat sensor, and the control unit may be configured for reading temperature measurements from the combustion heater heat sensor, and the control unit may be configured for turning off the combustion heater if the temperature measurements are above a set first temperature.
[0053] Turning off the combustion heater if it reaches a set first temperature may be a security measurement that may increase the safety of the modular heating system. If for example the circulation of the working fluid in the working fluid loop or the circulation of the water in the water loop stops, the temperature within the combustion heater may reach undesirable values, and it may be advantageous to turn off the combustion heater. The set first temperature may for example be between 80 to 110°C, for example 90°C or 100°C.
[0054] P31634PC00 P31634PC00 description and claims -for filingThe water loop may comprise a water loop heat sensor, and the control unit may be configured for reading water temperature measurements from the water loop heat sensor, and the control unit may be configured for turning off the combustion heater if the water temperature measurements are above a set second temperature.
[0055] The control unit may also be configured for reading water temperature measurements from a heat sensor of the hot tub, and the control unit may be configured for turning off the combustion heater if the water temperature measurements are above a set third temperature.
[0056] The set second and / or third temperature may for example be 44°C.
[0057] This may prevent overheating of the water in the hot tub or pool, and may thus increase the safety of the modular heating system.
[0058] The control unit may be configured for notifying the user, via for example a sound alarm or via an output device, if the water temperature, measured in the water loop or in the hot tub, reaches a set fourth temperature. The set fourth temperature may for example be 42.5°C.
[0059] The control unit may also turn off the combustion heater, if the water temperature, measured in the water loop or in the hot tub, reaches a set third temperature. If the water temperature reaches the set third temperature, the control unit may also turn off the working fluid pump and / or the fuel pump and / or the water pump. The set third temperature may for example be 44°C.
[0060] Turning off the combustion heater and the different pumps of the modular heating system if the temperature in the water loop reaches the set third temperature may be a security measurement that may increase the safety of the modular heating system.
[0061] The control unit may also be configured for turning off the combustion heater when the water temperature reaches a value set by the user through an input device connected to the control unit, making the modular heating system user friendly.
[0062] In an embodiment of the invention, the modular heating system may further comprise an
[0063] P31634PC00 P31634PC00 description and claims -for filinginternal water flow sensor for measuring flow of water in the water loop, and the control unit may be configured for reading water flow measurements from the internal water flow sensor. The control unit may be configured to turn off the combustion heater, and / or the working fluid pump and / or the fuel pump and / or the water pump, if the flow of water is measured to be above or below a set range of values. If the flow of water in the water loop stops, for example due to a malfunction of a water pump, the control unit may turn off the combustion heater, and / or the working fluid pump and / or the fuel pump and / or the water pump.
[0064] Alternatively or additionally, the control unit may be configured for reading water flow measurements from a flow sensor of the hot tub.
[0065] In an embodiment of the invention, the modular heating system may further comprise a user input-output device. A user may set a desired temperature of the water in the hot tub or pool, such that the control unit turns off the combustion heater when the desired temperature is reached. A user may use the user input-output device to turn on and off the combustion heater, and / or the fuel pump, and / or the working fluid pump, and / or the water pump. The user input-output device may read out information about the modular heating system or the hot tub, such as temperature in the combustion heater, temperature of the water, or flow of the water. The user input-output device may read out warning signals to the user if a set temperature is reached. The user input-output device may read out error messages if something in the modular heating system malfunctions.
[0066] The user input-output device may be advantageous when the modular heating system is used with a hot tub that does not have an own input-output device.
[0067] Alternatively, or additionally the control unit may be configured for receiving input from an external input-output device of the hot tub, and / or sending information to the external input-output device.
[0068] Most hot tub or pools typically have their own input-output device that a user may use to control the water flow and the temperature, etc. Controlling the modular heating system through the hot tub's own input-output device may make the modular heating system
[0069] P31634PC00 P31634PC00 description and claims -for filingmore user friendly.
[0070] The control unit may send the same information to the external input-output device as to the user input-output device as explained above.
[0071] In a second aspect the invention relates to a hot tub heating system comprising:
[0072] - a hot tub;
[0073] - a modular heating system according to the first aspect of the invention, wherein the water inlet of the modular heating system is connected with a water outlet of the hot tub, and the water outlet of the modular heating system is connected with a water inlet of the hot tub, and;
[0074] - a water pump for circulating the water from the water inlet of the modular heating system to the water outlet of the modular heating system.
[0075] The water pump may be integrated with the hot tub. The water pump may be integrated with the modular heating system, either within the housing or outside.
[0076] The effect of the features of the second aspect of the invention are the same as those explained in relation to the first aspect of the invention.
[0077] In an embodiment of the invention, the hot tub may comprise an input-output device, and the control unit of the modular heating system may be connected to the input-output device of the hot tub.
[0078] In a third aspect, the invention relates to a method for heating water in a hot tub, the method comprising the steps of:
[0079] - providing a hot tub with water;
[0080] - providing a modular heating system according to the first aspect of the invention;
[0081] - connecting the water inlet of the modular heating system with a water output of the hot tub;
[0082] - connecting the water outlet of the modular heating system with a water inlet of the hot tub;
[0083] - circulating water from the hot tub into the water inlet of the modular heating system, through the water loop and out from the water outlet of the modular heating system;
[0084] P31634PC00 P31634PC00 description and claims -for filing- circulating the working fluid through the working fluid loop;
[0085] - heating the working fluid in the combustion heater;
[0086] - heating the water in the first heat exchanger; and
[0087] - heating the water or the working fluid in the second heat exchanger;
[0088] In a fourth aspect, the invention relates to a method for safely heating water in a hot tub, the method comprising the steps of:
[0089] - providing a hot tub with water;
[0090] - providing a modular heating system according to the first aspect of the invention;
[0091] - connecting the water inlet of the modular heating system with a water output of the hot tub;
[0092] - connecting the water outlet of the modular heating system with a water inlet of the hot tub;
[0093] - circulating water from the hot tub into the water inlet of the modular heating system, through the water loop and out from the water outlet of the modular heating system; - circulating the working fluid through the working fluid loop;
[0094] - heating the working fluid in the combustion heater;
[0095] - heating the water in the first heat exchanger;
[0096] - heating the water or the working fluid in the second heat exchanger; and one or more of the steps of:
[0097] - notifying a user if water temperature measurements from the water loop heat sensor and / or from the heat sensor of the hot tub, is above a set second temperature;
[0098] - turning off the combustion heater if water temperature measurements from the water loop heat sensor and / or from the heat sensor of the hot tub, is above a set third temperature; or
[0099] - turning off the combustion heater if temperature measurements of the combustion heater heat sensor are above the set first temperature;
[0100] - interrupting internal circuits in the modular heating system if water temperature measurements from the water loop heat sensor and / or from the heat sensor of the hot tub are above a set fourth temperature.
[0101] The set first temperature may for example be 80 to 110°C, for example 90°C or 100°C.
[0102] P31634PC00 P31634PC00 description and claims -for filingThe set second temperature may be 42,5°C. The set third temperature may be 44°C. The set fourth temperature may be 48°C.
[0103] In a fifth aspect, the invention relates to a method for connecting a modular heating system to a hot tub, the method comprising the steps of:
[0104] - providing a hot tub with water;
[0105] - providing a modular heating system according to the first aspect of the invention;
[0106] - connecting the water inlet of the modular heating system with a water output of the hot tub;
[0107] - connecting the water outlet of the modular heating system with a water inlet of the hot tub;
[0108] The method may further comprise the step of:
[0109] - providing a water pump for circulating water through the water loop of the modular heating system.
[0110] BRIEF INTRODUCTION OF THE FIGURES
[0111] In the following is described examples of preferred embodiments illustrated in the accompanying drawings, wherein:
[0112] Fig. 1 shows an example of a modular heating system according to the invention;
[0113] Fig. 2 shows another example of a modular heating system according to the invention;
[0114] DETAILED DESCRIPTION OF EMBODIMENTS
[0115] Any positional indications refer to the position shown in the figures.
[0116] In the figures, same or corresponding elements are indicated by same reference numerals. For clarity reasons, some elements may in some of the figures be without reference
[0117] P31634PC00 P31634PC00 description and claims -for filingnumerals.
[0118] A person skilled in the art will understand that the figures are just principal drawings. The relative proportions of individual elements may also be distorted.
[0119] Figure 1 shows an example of a modular heating system 1 for a hot tub (not shown), particularly suitable for retrofitting to a hot tub.
[0120] The modular heating system 1 comprises a housing 50. The housing 50 is completely welded and made of a corrosion resistant material such as stainless steel (for example of grade 304 or 316). External connection points (inlets and outlets) are made easily accessible on the outside of the housing 50. The housing further comprises one or more service hatches (not shown) so that internal components may be visually inspected and serviced. The one or more hatches typically comprises a seal, for example an O-ring or a rubber strip to prevent water from entering the housing 50 through the closed hatch.
[0121] The modular heating system 1 further comprises a combustion heater 10 within the housing 50. The combustion heater 10 comprises a fuel inlet 15, through which fuel is pumped into the combustion chamber (not shown) of the combustion heater 10, by a fuel pump 60 connected to a fuel reservoir 61. The fuel pump 60 is provided within the housing 50, and connected with a fitting for a standard fuel hose on the outside of the housing 50, for easy connection to a fuel hose from the fuel reservoir.
[0122] In the examples shown the fuel pump 60 is provided within the housing 50, but in other examples, the fuel pump 60 is provided on the outside of the housing 50. In the examples shown the fuel reservoir 61 is provided on the outside of the housing 50. In other examples, the fuel reservoir 61 may be provided within the housing 50, accessible for refilling though a hatch in the housing 50. The combustion heater 10 may be configured for burning different fuel types, such as diesel, biodiesel or gas. A typical effect of the combustion heater 10 may be 2 to 10 kW, but the effect may be higher or lower depending on the size of the hot tub.
[0123] The combustion heater 10 further comprises an air inlet 11 and an outlet 12 for exhaust gases. Air is sucked into the combustion chamber through the air inlet 11. The air passes
[0124] P31634PC00 P31634PC00 description and claims -for filingfirst a coarse filter 112, positioned on the outside of the housing 50, and then a fine filter 133, positioned on the inside of the housing 50, to reduce the amount of particles entering the combustion chamber.
[0125] A working fluid is pumped through a working fluid loop 35 by a working fluid pump 31. The working fluid is circulated, by means of the working fluid pump 31, through the combustion heater 10 between a working fluid inlet 13, and a working fluid outlet 14, to heat the working fluid in the combustion heater 10.
[0126] The combustion heater 10 utilises an efficient air-to-fluid principle, wherein the heat due to the burning fuel is transferred to the working fluid. Supply of fuel to the combustion chamber starts the combustion process. In one embodiment the fuel pump 60 may be an electrical fuel pump that provides a uniform and precise supply of fuel. The fuel may be injected into the combustion chamber through an injector or a nozzle, that may evenly distribute the fuel to ensure an even and efficient combustion.
[0127] To start the combustion, an electrical ignition system that may comprise a glow plug or a heating element, may be used. The ignition system ignites the fuel at start-up, and after the ignition the combustion is maintained inside the combustion chamber by a steady supply of fuel, through the fuel inlet 15, and oxygen, through the air inlet 11.
[0128] When burning the fuel in the combustion chamber, the working fluid is heated such that hot working fluid is emitted though the working fluid outlet 14. The working fluid may typically be glycol, ethylene glycol, water, or propylene glycol.
[0129] By "hot working fluid" is here meant working fluid heated by the combustion process in the combustion heater. The hot working fluid is therefore warmer than the working fluid entering the combustion heater through the working fluid inlet 13. The hot working fluid is sufficiently heated such that the heat can be transferred to water in the water loop in the first heat exchanger.
[0130] The combustion heater 10 further comprises an internal heat exchanger (not shown) for transferring heat generated by the combustion to the working fluid.
[0131] P31634PC00 P31634PC00 description and claims -for filingThe combustion process creates hot exhaust gases that are directed into the internal heat exchanger. The working fluid will be heated as it flows through channels in the internal heat exchanger. As the exhaust gases pass around these channels, they transfer heat to the working fluid, and the exhaust gases are then cooled before being led out through the outlet 12 for exhaust gases.
[0132] The modular heating system 1 further comprises a water inlet 21 and a water outlet 22 in fluid connection with the water inlet 21, such that a water loop 25 between the water inlet 21 and the water outlet 22 is formed. The water inlet 21 and the water outlet 22 both comprises an external connection point 211, 221 on the outside of the housing 50 such that water pipes or hoses from the hot tub may easily be connected to the water inlet 21 and the water outlet 22 through the external connection points 211, 221. The external connection points 211, 221 may typically comprise a fitting such as a threaded nipple fitting. The fittings, the water inlet 21 and the water outlet 22 are preferably made of a corrosion resistant material such as stainless steel (for example of grade 304 or 316).
[0133] In the shown embodiment, the water inlet 21 and the water outlet 22 are connected with the water circulation system (not shown) of the hot tub, so there is no need of an additional water pump. The water circulation system of the hot tub is simply extended so that it also passes through the water loop 25 of the modular heating system 1.
[0134] The modular heating system 1 further comprises a first heat exchanger 41 connected to the working fluid loop 35, such that hot working fluid from the combustion heater 10 passes thought the working fluid outlet 14 and into the first heat exchanger 41. The first heat exchanger 41 is also connected to the water loop 25, such that heat is transferred from the hot working fluid to the water in the water loop 25. The working fluid is therefore cooled down in the first heat exchanger 41, and cold working fluid enters the combustion heater 10 through the working fluid inlet 13 for re-heating.
[0135] In the figures, hot working fluid and hot water is illustrated by filled-in arrows and cold working fluid and cold water is illustrated by empty arrows. The hatched arrows represent an intermediate temperature.
[0136] P31634PC00 P31634PC00 description and claims -for filingIn the embodiment shown, the first heat exchanger 41 is a parallel-flow heat exchanger. Water and the hot working fluid enter the first heat exchanger 41 at the same end, as illustrated in the figures. The working fluid and the water flow through the first heat exchanger 41, in the same direction, towards the opposite end. In other examples (not shown) the first heat exchanger 41 may be a counter-flow heat exchanger.
[0137] The first heat exchanger 41 comprises an expansion tank 36, to compensate for volume changes of the working fluid due to temperature changes. The expansion tank 36 may be easily accessible inside the housing 50 through a hatch (not shown) such that a user may easily inspect the expansion tank and replenish the working fluid if needed. The first heat exchanger 41 further comprises a galvanic anode to decrease the rate of corrosion of the first heat exchanger 41.
[0138] A second heat exchanger 42 is connected to the outlet 12 for exhaust gases of the combustion heater 10. On the other end of the second heat exchanger 42, an exhaust pipe 121 is connected to direct the exhaust gases out of the housing 50. The second heat exchanger 42 is also connected to the water loop 25 in the shown embodiment. After the exhaust gases has passed the internal heat exchanger of the combustion heater 1, the exhaust gases are still hot and may be used to heat the water in the water loop 25. The exhaust gases are directed out through the outlet 12 and into the second heat exchanger 42. In the second heat exchanger 42, heat from the hot exhaust gases is transferred to the water in the water loop 25. The heated water then passes from the second heat exchanger 42 to the first heat exchanger 41 a heat exchanger connection 43, for further heating. The exhaust gases are cooled down and directed out from the housing 50 through the exhaust pipe 121. The second heat exchanger 42 may be dimensioned such that the temperature of the exhaust gases is reduced from approximately between 400 and 700°C when entering the second heat exchanger 42, to approximately 50°C when directed out from the housing 50, which may reduce the heat loss of the modular heating system 1 and may increase the safety for the users of the modular heating system 1.
[0139] In the embodiment shown, the second heat exchanger 42 is a counter-flow heat exchanger. Water and the hot exhaust gases enter the second heat exchanger 42 at
[0140] P31634PC00 P31634PC00 description and claims -for filingopposite ends, as illustrated in the figures. The water and the exhaust gases flow paral-lelly through the second heat exchanger 42, in opposite directions. In other examples (not shown) the second heat exchanger 42 may be a parallel-flow heat exchanger.
[0141] The first and second heat exchangers 41, 42 are provided within the housing 50. The working fluid loop 25 and the working fluid pump 31 are also provided within the housing 50. In the figures, the working fluid pump 31 is positioned between the first heat exchanger 41 and the working fluid inlet 13, such that the working fluid pump 31 pumps working fluid that has been cooled down in the first heat exchanger. In other examples, the working fluid pump 31 may be positioned elsewhere along the working fluid loop 25, for example between the working fluid outlet 14 and the first heat exchanger 41.
[0142] Water used in hot tubs or pools may typically comprise compounds such as chlorine compounds or bromine compounds for hygienic reasons. These compounds may increase the rate of corrosion of the material that are in contact with these compounds. It may therefore be advantageous that the components of the modular heat exchanger 1 in contact with either water or working fluid or both, are made of a corrosion resistant material, such as stainless steel (for example of grade 304 or 316).
[0143] The heating of the water in the water loop 25 in two steps, in the first and second heat exchanger may reduce heat loss of the modular heating system 1 and increase the total efficiency of the modular heating system 1. In the modular heating system 1 shown in the figures, the water is directed first through the second heat exchanger 42 such that the water is firstly heated by the exhaust gases, and then though the first heat exchanger 41 such that the water is subsequently heated by the working fluid.
[0144] The modular heating system 1 further comprises a control unit 70. The control unit 70 controls the combustion heater 1, the working fluid pump 31 and the fuel pump 60.The modular heating system 1 further comprises different sensors to monitor the operation of the modular heating system 1. A combustion heat sensor (not shown) measures the internal temperature within the combustion heater 1, a water loop heat sensor (not shown) measures the temperature of the water within the water loop 25, and a flow sensor in the water loop for measuring the flow of water through the water loop 25. The water loop
[0145] P31634PC00 P31634PC00 description and claims -for filingsensor is preferably placed close to the water outlet 22 to measure the temperature of the water that will enter the hot tub.
[0146] The control unit 70 receives data from these sensors and based on these data, the control unit 70 controls the pumps and the combustion heater 1. For example, if the temperature within the combustion heater 1 becomes too high, for example if the working fluid pump 31 malfunctions and the working fluid is not circulating through the combustion heater 1, then the control unit 70 may be configured for shutting down the combustion heater 1 and to turn off the fuel pump 60. The control unit 70 may also be configured for turning off the combustion heater when a desired temperature of the water is reached. The control unit 70 may also control the combustion process by adjusting a burner of the combustion heater 1 and / or by controlling the fuel pump 60.
[0147] In the example shown in Fig. 1, the control unit 70 is connected to the external input-out-put device 72 of the hot tub through a mutli-contact (not shown). From the input-output device 72 of the hot tub, the control unit 70 may also read data from sensors of the hot tub, such as flow sensors of the water circulation system of the hot tub, and heat sensors of the hot tub to measure the temperature of the water in the hot tub. The control unit 70 may control the combustion heater and the pumps based on data received from the sensors of the hot tub in the same way as described above.
[0148] Furthermore, a user of the hot tub may set different settings using the input-output device 72 of the hot tub, such as a desired temperature. The control unit 70 is configured to turn off the combustion heater 1 when the desired temperature is reached.
[0149] Through the multi-contact, electricity to power the control unit 70, the working fluid pump 31, the fuel pump 60 and the combustion heater 10 is also provided. The current may pass through a converter (not shown) for transforming the voltage to 12 or 24 V DC to power the components.
[0150] Referring now to Fig. 2, which shows another example of a modular heating system 1 according to the invention. This example will only be discussed insofar as it differs from the example shown in Fig. 1.
[0151] P31634PC00 P31634PC00 description and claims -for filingThe first difference is that the modular heating system 1 of Fig. 2 comprises a water pump 26. The water pump 26 makes this modular heating system 1 more suitable for use with a hot tub or pool that is not already equipped with its own water circulation system, such as a simple wood-fired hot tub. The water pump 26 is connected to the water inlet 21 of the modular heating system for pumping water through the water loop 25. The water pump 26 is provided with a connection point 261 for connecting with a water outlet of the hot tub. The connection point 261 may typically comprise a fitting such as a threaded nipple fitting. The fitting is preferably made of a corrosion resistant material such as stainless steel (for example of grade 304 or 316).
[0152] In the example shown, the water pump 26 is positioned outside the housing 50. In other examples, the water pump 26 is provided within the housing 50.
[0153] A second difference is that the modular heating system 1 comprises a user input-output device 71. The control unit 70 may be connected to the user input-output device through a physical connection, such as a cable, or through a wireless connection, such as through Bluetooth or Wi-Fi. A user of the hot tub may set different settings using the user inputoutput device 71, such as a desired temperature. The control unit 70 is configured to turn off the combustion heater 1 when the desired temperature is reached. The user inputoutput device 72 may for example be a display with tactile buttons for receiving user input, and for output of information, such as temperature, to the user. The user input-out-put device 72 may also be a mobile app.
[0154] In another example, the control unit 70 is connected to both a user input-output device 71 and an input-output device 72 of the hot tub.
[0155] A further difference with the modular heating system 1 in Fig.2 is that the components of the modular heating system 1, such as the combustion heater 10, the fuel pump 60, the working fluid pump 31, the control unit 70 and the water pump 26 are powered by a separate power source 74. The power source 74 may for example be an AC mains socket or a battery. The power source typically provides the modular heating system 1 with AC voltage of 220 V. The current passes through a converter 73 for transforming the voltage to 12 or 24 V DC to power the components.
[0156] P31634PC00 P31634PC00 description and claims -for filingIt should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. Use of the verb "comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.
[0157] The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.
[0158] P31634PC00 P31634PC00 description and claims -for filing
Claims
C l a i m s1. Modular heating system (1) for a hot tub, the modular heating system (1) comprising:- a combustion heater (10) comprising:- an air inlet (11) and an outlet (12) for exhaust gases;- a fuel inlet (15); and- a working fluid inlet (13) and a working fluid outlet (14), the combustion heater (10) being configured for heating a working fluid;- a water inlet (21) and a water outlet (22) in fluid communication with the water inlet (21), such that a water loop (25) between the water inlet (21) and the water outlet (22) is formed, the water inlet (21) being configured for receiving water from the hot tub and the water outlet (22) being configured for emitting water to the hot tub;- a working fluid pump (31) for circulating a working fluid between the working fluid outlet (14) to the working fluid inlet (13) in a working fluid loop (35);- a first heat exchanger (41) connected to the working fluid loop (35) and to the water loop (25), such that the water is heated up by the working fluid in operational use; andcharacterised in that the modular heating system further comprises a second heat exchanger (42) connected to the outlet (12) for exhaust gases of the combustion heater (10) and connected to one of the working fluid loop (35) or the water loop (25) such that one of the working fluid or the water is heated by exhaust gases from the combustion heater (10) in operational use;and in that the combustion heater (10), the first heat exchanger (41), the second heat exchanger (42), and the working fluid pump (31) are provided within a housing (50).
2. The modular heating system (1) according to claim 1, wherein the second heat exchanger (42) is connected to the water loop (25) such that the water is heated up by exhaust gases from the combustion heater (10) in operational use.P31634PC00 P31634PC00 description and claims -for filing3. The modular heating system (1) according to claim 2, wherein the first and the second heat exchangers (41, 42) are connected to the water loop (25) in series.
4. The modular heating system (1) according to claim 3 wherein the first and the second heat exchangers (41, 42) are connected to the water loop (25) in series such that the water in the water loop (25) is first heated in the second heat exchanger (42) and then in the first heat exchanger (41) in operational use.
5. The modular heating system (1) according to claim 2, wherein the water loop (25) is divided into a first and a second water sub loop, the first water sub loop being connected to the first heat exchanger (41) and the second water sub loop being connected to the second heat exchanger (42), such that the first and the second heat exchangers (41, 42) are connected to the water loop (25) in parallel.
6. The modular heating system (1) according to any of the previous claims, wherein the modular heating system (1) further comprising a water pump (26) for circulating water from the water inlet (21) to the water outlet (22).
7. The modular heating system (1) according to any of the previous claims, wherein the modular heating system (1) comprises a fuel pump (60) in connection with the fuel inlet (15) for pumping fuel into the combustion heater (10).
8. The modular heating system (1) according to claim 7, wherein the fuel pump (60) is provided within the housing (50).
9. The modular heating system (1) according to claim 8, wherein the modular heating system further comprises a fuel reservoir (61) within the housing (50), the fuel reservoir (61) being in connection with the fuel pump (60).
10. The modular heating system (1) according to any of the previous claims, wherein the first heat exchanger (41) comprises an expansion tank (36).
11. The modular heating system (1) according to any of the previous claims, wherein the first heat exchanger (41) and / or the second heat exchanger comprises a galvanic anode (37).P31634PC00 P31634PC00 description and claims -for filing12. The modular heating system (1) according to any one of the previous claims, wherein the modular heating system (1) further comprises a control unit (70) for controlling the combustion heater (10).
13. The modular heating system (1) according to claim 12, when dependent on claims 7, wherein the control unit (70) is configured for controlling the working fluid pump (31) and the fuel pump (60).
14. The modular heating system (1) according to claim 12 or 13, wherein the combustion heater (10) comprises a combustion heater heat sensor, and the control unit (70) is configured for reading temperature measurements from the combustion heater heat sensor, and the control unit (70) is configured for turning off the combustion heater (10) if the temperature measurements are above a set first temperature.
15. The modular heating system (1) according to any one of claims 12 to 14, wherein the water loop (25) comprises a water loop heat sensor, and the control unit (70) is configured for reading water temperature measurements from the water loop heat sensor, and the control unit (70) is configured for turning off the combustion heater (10) if the water temperature measurements are above a set second temperature.
16. The modular heating system (1) according to any one of claims 12 to 15, wherein the control unit (70) is configured for reading water temperature measurements from a heat sensor of the hot tub, and the control unit (70) is configured for turning off the combustion heater (10) if the water temperature measurements are above a set third temperature.
17. The modular heating system (1) according to any of claims 12 to 16, wherein the modular heating system (1) further comprises an internal water flow sensor for measuring flow of water in the water loop (25), and the control unit (70) is configured for reading water flow measurements from the internal water flow sensor.P31634PC00 P31634PC00 description and claims -for filing18. The modular heating system (1) according to any of claims 12 to 17, wherein the control unit (70) is configured for reading water flow measurements from a flow sensor of the hot tub.
19. The modular heating system (1) according to any of the claims 12 to 18, wherein the modular heating system (1) further comprises a user input-output device (71).
20. The modular heating system (1) according to any of the claims 12 to 19, wherein the control unit (70) is configured for receiving input from an external input-out- put device (72) of the hot tub, and / or sending information to the external inputoutput device.
21. A hot tub heating system comprising:- a hot tub;- a modular heating system (1) according to any of the previous claims, wherein the water inlet (21) of the modular heating system (1) is connected with a water outlet of the hot tub, and the water outlet (22) of the modular heating system (1) is connected with a water inlet of the hot tub, and;- a water pump for circulating the water from the water inlet (21) of the modular heating system (1) to the water outlet (22) of the modular heating system (1).
22. A hot tub heating system according to claim 20, when dependent on claim 20, wherein the hot tub comprises an input-output device (71), and wherein the control unit (70) of the modular heating system (1) is connected to the input-output device (71) of the hot tub.
23. Method for heating water in a hot tub, the method comprising the steps of:- providing a hot tub with water;- providing a modular heating system (1) according to any of the claims 1 to 20; - connecting the water inlet (21) of the modular heating system (1) with a water output of the hot tub;- connecting the water outlet (22) of the modular heating system (1) with aP31634PC00 P31634PC00 description and claims -for filingwater inlet of the hot tub;- circulating water from the hot tub into the water inlet (21) of the modular heating system (1), through the water loop (25) and out from the water outlet (22) of the modular heating system (1);- circulating the working fluid through the working fluid loop (35);- heating the working fluid in the combustion heater (10);- heating the water in the first heat exchanger (41); and- heating the water or the working fluid in the second heat exchanger (42);24. A method for safely heating water in a hot tub, the method comprising the steps of:- providing a hot tub with water;- providing a modular heating system (1) according to any of the claims 14 to 16; - connecting the water inlet (21) of the modular heating system (1) with a water output of the hot tub;- connecting the water outlet (22) of the modular heating system (1) with a water inlet of the hot tub;- circulating water from the hot tub into the water inlet (21) of the modular heating system (1), through the water loop (25) and out from the water outlet (22) of the modular heating system (1);- circulating the working fluid through the working fluid loop (35);- heating the working fluid in the combustion heater (10);- heating the water in the first heat exchanger (41);- heating the water or the working fluid in the second heat exchanger (42); and one or more of the steps of:- notifying a user if water temperature measurements from the water loop heat sensor and / or from the heat sensor of the hot tub, is above a set fourth temperature;- turning off the combustion heater (10) if water temperature measurements from the water loop heat sensor are above the set second temperature;- turn off the combustion heater (10) if water temperature measurements from the heat sensor of the hot tub, are above the set third temperature;P31634PC00 P31634PC00 description and claims -for filing- turning off the combustion heater (10) if temperature measurements of the combustion heater (10) heat sensor are above the set first temperature;- interrupting internal circuits in the modular heating system (1) if water temperature measurements from the water loop heat sensor and / or from the heat sensor of the hot tub are above a set fifth temperature.
25. A method for connecting a modular heating system to a hot tub, the method comprising the steps of:- providing a hot tub with water;- providing a modular heating system (1) according to any of the claims 1 to 20; - connecting the water inlet (21) of the modular heating system (1) with a water output of the hot tub;- connecting the water outlet (22) of the modular heating system (1) with a water inlet of the hot tub;26. The method according to claim 25 further comprising the step of:- providing a water pump for circulating water through the water loop (25) of the modular heating system (1).P31634PC00 P31634PC00 description and claims -for filing