Electrically heated sauna stove

Abstract

The invention relates to an electrically heated sauna stove, in which one or more heating elements (1) heat sauna stones and / or bricks (2). The heating element(s) (1) are in contact with a ceramic shield or shields (3) with extremely high thermal conductivity, exceeding 10 W(mK)⁻¹, on their inner surface. On the outer surface of this shield or shields (4), sauna stones and / or bricks (2) are in contact.

Description

[0001] ELECTRICALLY HEATED SAUNA STOVE

[0002] FIELD OF THE INVENTION

[0003] The invention relates to a sauna stove that is heated by electricity.

[0004] PURPOSE OF THE INVENTION

[0005] The purpose of the invention is to efficiently transfer heat from the heating element to the sauna stones and / or bricks.

[0006] BACKGROUND OF THE INVENTION

[0007] For a long time, there has been an effort to solve the problem of how to efficiently transfer heat from the heating element to the sauna stones or bricks. If the heat does not transfer efficiently to the sauna stones, several undesirable effects occur. It is relatively easy to heat a sauna to high or even excessive temperatures, but the challenge is to heat the sauna stones or bricks sufficiently without overheating the sauna itself. A sauna temperature of 60-80 degrees Celsius is sufficient, with 70 degrees Celsius often being the optimal temperature depending on the sauna and stove. At 100 degrees Celsius, it is difficult to achieve moist steam in an electric sauna.

[0008] Steam, or "loyly," refers to the vapor rising from water thrown onto the hot sauna stove. Loyly is an essential part of the sauna experience, providing a pleasant temperature and a relaxing effect. It may also have health benefits and plays a crucial role in sauna ventilation. Without throwing water on the stones, the air in the sauna stratifies, with the hottest air accumulating near the ceiling.

[0009] If heat is not effectively transferred to the sauna stones, multiple issues arise. For example, the heating elements experience significant stress, and the sauna stones do not heat up quickly enough, which is essential for sauna use. The heating elements of the stove cannot withstand overheating and will break.

[0010] Hot heating elements and water thrown onto them also create other problems, such as fine particle emissions from the heating elements in an electric sauna (retrieved on April 7, 2024, from https: / / saunologia.fi / tutkimus-sahkokiukaista-pienhiukkasia-saunailmaa / ).

[0011] Another reported issue is that red-hot electric heating elements release positive ions into the air, especially when water is poured onto them. This problem specifically concerns electric sauna stoves, and some designs have attempted to mitigate it by insulating the heating elements from the stones with an air channel. However, this solution is ineffective for heating the sauna stones, as they do not reach sufficient temperatures, resulting in weak steam production.

[0012] DESCRIPTION OF THE INVENTION

[0013] The invention is characterized by the features presented in the characteristic section of claim 1.

[0014] Heating elements are well known and come in various forms, including tubular, rod-like, and spiral-shaped designs. They are available in many different shapes, sizes, and power levels. Control systems are also well known and can be managed remotely.

[0015] Attempts to solve these problems include separating the heating elements from the sauna stones and / or bricks using an air channel. However, this often results in the sauna air becoming excessively hot while the sauna stones or bricks do not reach adequate temperatures for producing steam, especially over a wider area.

[0016] From the customer’s perspective, the stove should be durable. Since warranties do not cover damages caused by small, crumbling, low-quality, or tightly packed sauna stones, the responsibility falls on the owner or user. Regularly rearranging the sauna stones to remove broken or crumbled pieces before they damage the heating elements is laborious and timeconsuming.

[0017] Various solutions have been proposed, such as the patent publication US5136734: A Method of Heating a Sauna and Sauna Stove (application filed on December 1, 1986, granted on August 11, 1992), which describes an electrically heated sauna stove equipped with a fan.

[0018] One proposed solution for protecting the heating element has been to separate it from the sauna stones with an air channel. This approach heats the sauna itself but does not sufficiently heat the sauna stones over a large enough area to produce good steam. It is essential that the sauna stones reach high enough temperatures while keeping the sauna at a comfortable temperature.

[0019] BRIEF DESCRIPTION OF THE FIGURES

[0020] Figure 1 is a schematic diagram of an electrically heated sauna stove in which one or more heating elements (1) heat the sauna stones and / or bricks (2). The heating elements (1) are in contact with a ceramic shield or shields (3) that have excellent thermal conductivity, with a thermal conductivity value exceeding 10 W(mK) Outside this shield or shields, the sauna stones and / or bricks (2) are in direct contact. The heating element is able to move due to thermal expansion clearance (4). The stove includes an electronic control unit (6) with both local and remote control capabilities. A temperature sensor (7) is installed in the stove. The outer casing (5) of the stove consists of a metal grid, except at the top, where there is no metal grid.

[0021] DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0022] The invention relates to a sauna stove where the heating element or elements (1) are in direct contact with the inner side of a ceramic shield or shields (3) with a thermal conductivity exceeding 10 W(mK) Outside this shield or shields (4), sauna stones and / or bricks (2) are in contact. The thickness of the shield(s) (4) ranges from 1 to 200 mm and may fully or partially cover the heating element(s) (1).

[0023] The heating elements can be tubular, rod-like, or spiral-shaped, typically ranging in power from 1 to 10 kW. A temperature sensor (7) provides real-time information about the stove’s temperature, and an additional temperature sensor mounted on the sauna wall can be used to regulate heating (6).

[0024] The stove may contain one or multiple heating elements, each of which can be individually regulated and may be fully or partially covered by one or more shields (3), allowing for thermal expansion clearance (4). The outer casing (5) of the stove may be entirely a metal grid, only partially a grid, or fully enclosed, with only the top layer of stones visible. EXAMPLES

[0025] Example 1

[0026] A 5000 W heating element (1) is enclosed in a silicon carbide-containing protective shield (3) with a thickness of 10 mm and a thermal conductivity of 35 \V(mK) fully covering the heating element. Outside this silicon carbide-containing shield, sauna stones (2) are in direct contact with the shield and with each other. The heating element (1) is allowed to move due to thermal expansion clearance (4). The stove includes an electronic control unit (6) with both local and remote control capabilities. A temperature sensor (7) is installed in the stove. The outer casing (5) consists of a metal grid, with no grid on the top.

[0027] It is obvious to those skilled in the art that the invention is not limited to the details of the above embodiment's.

Claims

CLAIMS1. An electrically heated sauna stove, in which one or more heating elements (1) heat sauna stones and / or bricks (2), characterized in that the heating element or elements (1) are in contact with a ceramic shield or shields (3) that conduct heat exceptionally well, with a thermal conductivity exceeding 10 W(mK) on their inner surface, and on the outer surface of this shield or these shields (4), sauna stones and / or bricks (2) are in contact.

2. A sauna stove according to claim 1, characterized in that the ceramic shield or shields (3) that conduct heat exceptionally well contain silicon carbide, silicon nitride, beryllium oxide, aluminum oxide, and / or aluminum nitride.

3. A sauna stove according to claim 1, characterized in that the thickness of the ceramic shield or shields (4) that conduct heat exceptionally well is 1-200 mm, and one or more heating elements can be individually or collectively covered entirely or partially by the shield or shields.

4. A sauna stove according to claim 1, characterized in that the sauna stones and / or bricks (2) contain olivine, olivine diabase, granite, soapstone, or olivine concrete made from crushed olivine mixed with cement, or fired ceramic heat-storing sauna stones.

5. A sauna stove according to claim 1, characterized in that the heating element or elements (1) are tubular, cartridge-type, and / or coil-shaped and can be positioned in any orientation, such as vertically, horizontally, symmetrically centered, or asymmetrically off- center.

6. A sauna stove according to claim 1, characterized in that the heating element or elements (1) are capable of movement due to thermal expansion allowance (4).

7. A sauna stove according to claim 1, characterized in that the stove includes a fan.

8. A sauna stove according to claim 1, characterized in that the enclosed stove model has an openable lid.

9. A sauna stove according to claim 1, characterized in that the outer casing (5) of the stove is entirely or partially made of metal mesh.

10. A sauna stove according to claim 1, characterized in that the stove and / or its exterior are equipped with temperature (7) and humidity sensors and / or overheat protection, and the electric sauna stove control systems (6) are also remotely accessible.

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