- Calculation of furnace power
- Features of the tunnel furnace
- Number of stones, heater type, setting
- Steam generator or combination heater
- The right material and design for the sauna stove
- Why do you need a tank and a heat exchanger
- Sauna ovens with convection
It is not easy to choose a stove for a home bath or sauna, especially since some selection criteria are not entirely obvious. In this article, we will talk about how to correctly calculate and choose a stove for a bath, what types and design features of stoves are, and which purchase is definitely suitable for your steam room.
When choosing a furnace, absolutely all factors must be taken into account: both purely technical and those related to ease of use. Absolutely everything matters: from the material of the walls of the bath to the mode of use and the number of people visiting it.
Calculation of furnace power
Manufacturers offer a rather rough calculation based on the internal volume of the steam room. It is determined by multiplying the perimeter by the height of the ceiling; if there is a glass door, 2 m is conditionally added to the value3, and for each square meter of the wall without thermal insulation – 1.5 m3. Moreover, if a free-standing bath is made of a log cabin or is not upholstered with clapboard from the inside, the calculated volume is multiplied by 1.5.
A more correct option is to perform a simplified thermal engineering calculation of the bathhouse building, in which external and adjacent walls are delimited, the thermal conductivity of materials, the presence of thermal insulation of the floor and ceiling are taken into account. In this case, the final temperature inside the heated room should be taken as 70–75 ° С for a Russian bath and 90–100 ° С for a dry sauna. The result of the calculation is the total amount of heat loss, to which it remains to add the heat capacity of the stones.
When choosing a furnace power, more does not mean better. A greatly overestimated stove performance will not allow you to be inside the steam room when operating at full capacity, and by reducing the supply of firewood, you will not achieve the temperature required for vaporization.
Features of the tunnel furnace
The choice of a stove design for a bath begins with determining the type of firebox, it can be conventional or remote (tunnel, elongated). The latter option is optimal if next to the steam room there is a suitable adjoining room from which you can lay firewood.
Stoves with a conventional firebox are not so convenient, they steal precious oxygen from the steam room and disrupt heat exchange, attracting fresh cold air. In addition, there is no place for firewood and logs in a clean steam room..
If you plan to heat a remote firebox from a rest room, pay attention to stoves with a fireplace door. It will ideally fit into the decoration of the room and will give an incomparable presence of living fire..
Number of stones, heater type, setting
The highest quality steam in the bath is called light. It is formed at temperatures above 500 ° C, when water has time not only to heat up, but to break down into molecules. But if the stove heats up to such a temperature, then the air inside the room will be very hot, so stones are used to generate steam.
There are two types of heaters and each one finds its admirers. A closed direct-heated stove is typical for a Russian bath and rarely comes across an iron stove with it. Much more popular is an open-hearth stove, in which steam is harder to generate and much more stones are needed..
The number of stones that can be put into the stove’s heater is determined by the manufacturer, and based not on the power of the stove, but on the design features. But it is better to calculate the weight of the stones yourself, based on the principle of 15 kg for each cubic meter of the bath, plus 15 kg for each visitor.
Finding a stove with a suitable power rating and number of stones is not an easy task. As a last resort, you can increase the volume of the open heater by constructing a side fence for the stones yourself. But be sure to take the power reserve of the furnace, based on the calculation: 1 kW per 25 kg of stone.
Steam generator or combination heater
In some stoves, the stove is present only for show: steam generation occurs in a system of closed channels laid inside the outer casing. The temperature in them exceeds 600 ° C and the steam is really “light”.
But this feature is not implemented correctly by all manufacturers. In most cases, the steam generator fails after a couple of years of active use – nobody canceled the formation of scale.
In part, both approaches are well combined with a combined heater, in which water is first supplied to the stones with direct heating, and the generated steam becomes dispersed, already passing through the open stones.
The right material and design for the sauna stove
Cast iron is ideal for the walls of the firebox and stove. It does not fade and has a high heat capacity. But, unfortunately, it is rare. Chrome-plated stainless or alloy steel replaced cast iron. They have a very high dross formation temperature, but their heat capacity is significantly lower. In most modern furnaces, only grates are made of cast iron and you need to pay attention to their shape: the grate must maintain uniform combustion of even low-quality fuel.
The firebox and the main heat exchanger of a good furnace should be made of high-quality steel with a chromium content of at least 13%. Preference should be given to the presence of stamped elements, although the connection of parts by high-quality welding, especially by the plasma method, is not much inferior. The presence of additional ribs inside the firebox and chimney ducts is a good sign, so the heat from the flame is transferred faster.
The efficiency of the furnace largely depends on the presence of internal channels that impede and prolong the passage of gases and flames, which allows you to get more heat with minimal soot formation. At the same time, additional heat exchangers are rationally placed above the heater, where the smoke is not hot enough to heat the stones.
Why do you need a tank and a heat exchanger
The large amount of residual heat means its rational use. For example – for heating water. This is useful in many cases, which are provided in their own way in the design of furnaces. For example, stoves with a built-in tank allow you to heat up to 100 liters of water for bathing or watering stones.
In a number of projects, water heating is also required for heating adjacent premises. Furnaces with an additional heat exchanger have such a function, they are also used in conjunction with external tanks of a larger capacity. When choosing the power of such a furnace, you need to add the heat consumption for heating water in the heating system. Although in the end the power will still be less than if the whole bath was heated by air convection.
Sauna ovens with convection
One of the unpleasant features of using a low-quality stove is the high temperature difference between the floor and ceiling. The problem lies in the absence of full-fledged convection, the heated air does not circulate, but accumulates on the upper tiers.
Some sauna stoves are devoid of such a drawback due to convection channels that let air through the area of the firebox and heater, warming it up well. And temperature equalization is not the only plus. The steam room heats up so quickly and the lack of oxygen in it is felt less acutely.
Knowing these main differences between sauna stoves, you will greatly facilitate the choice. It remains to take into account only the aesthetic component so that the stove not only works productively, but also becomes an excellent decoration for the steam room..