- How does a metal stove-heater work?
- Metal stove in the bath – advantages and disadvantages
- We increase the heat capacity of a metal stove
- How to position the stove in the bath
- How to choose a metal stove
In this article: Arranging a stove made of metal; pros and cons of metal sauna stoves; how to install a stove in a bath; criteria for choosing a metal furnace; average cost of a metal heater.
An important, perhaps the main element of the bath is the stove, without which you can neither steam nor wash, not to mention heating this room. Classic brick or modern metal, wood-burning or powered by electricity – you need to carefully choose the type and design, think over how to position the stove in the bath so that it works with the greatest efficiency. In this article, we will consider metal stoves for a bath.
How does a metal stove-heater work?
Made of 5-6 mm metal (with a high chromium content, a smaller thickness is allowed – from 2 mm), the body contains three chambers – a blower, a firebox and a heater, combined in some models with a water tank. There are models of stoves for baths, in which the water in the tank is heated to 60 degrees of temperature from the gases flowing through the chimney. The chamber of the stove, depending on the models of the stove, can be open or closed – in the second variant, the heat capacity of the metal stove increases, but the period of its kindling increases. To exclude the possibility of penetration of flue gases into the bath room, the ash chamber and furnace are equipped with doors. The bottom of the combustion chamber is made of a special thick sheet of metal or cast iron.
Arrangement of a metal stove-heater: 1 – firebox, 2 – tank with lid, 3 – steam door, 4 – heater, 5 – ash pan.
The chimney outlet is located either in the heater chamber or in the furnace chamber. In the first variant, the stove must be tightly closed with a metal lid for the duration of the kindling, or the stove chamber is completely closed with metal on all sides and equipped with an opening with a door – the filler is heated in it by heat from the firebox and flue gases in contact with the stove through the grate. In the second, the firebox and the stove are separated by a sheet of metal, the heating of the stove filler occurs from contact with the firebox through a metal sheet and through contact with the chimney.
Manufacturers of metal stoves-heaters solve the problem of a hot body in two ways – with the help of a double body, or by installing two or three blocks of wood (larch, oak) around the perimeter of the stove. The air gap between the inner and outer metal casing in the first version prevents heat transfer between the casings and prevents the outer casing from heating to high temperatures that could lead to burns if accidentally touched. The wooden beam in the second version is attached at some distance from the metal body of the furnace and, although less efficiently than the double body, also prevents accidental contact with the furnace.
The choice and installation of a stove in a bathhouse, in the design of which the firebox and the stove do not communicate with each other, is the choice in favor of a continuous stove-stove. The laying of fuel in stoves of this design is carried out during the entire period of visiting the bath, while the possibility of penetration of carbon monoxide in the steam room is completely excluded. To simplify the kindling of continuous furnaces, most often gaseous or liquid fuels are burned in them. The temperature of the heater filler in continuous ovens is maintained at 220-250 ° С.
Batch stoves, in which the chambers of the stove and firebox are separated by a grate, and the stove itself is closed with a tight lid or completely closed, are melted with wood. A visit to a sauna with a stove of this type is allowed only after complete combustion of the fuel, otherwise removing the lid from the stove will cause gases to enter the sauna room. Closed-type stoves have a door for water supply and steam outlet; it is placed at a level slightly above the upper level of the backfill stones. Flames and hot gases heat stones in a stove with a closed stove to higher temperatures than in continuous stoves (about 500 ° C), however, the period of visiting the steam room is shorter – the absence of a constant heat source will cool the stove after it has been several once doused with water.
Metal stove in the bath – advantages and disadvantages
First of all – the low weight and easy installation of the stove in the bath. A brick stove in a bathhouse weighs about 2.5-6 tons; it requires an independent and solid foundation, otherwise shrinkage of the stove cannot be avoided. A metal stove weighs several times less and does not require a foundation; it is easy to find a place for it in a steam room with a small area. Light weight is one of the most important advantages of metal stoves, such as stoves, fireplaces and heating boilers.
Rapid heating of a metal heater. To heat a Russian stove in a bath, you will have to spend several hours and a lot of firewood – visiting such a bath must be planned and prepared in advance. It will take an hour and a half to light up a metal stove and warm up the air in the bath, depending on the size of the steam room and the power of the furnace – the metal heats up much faster than brickwork. Creating the necessary atmosphere in the bath, the metal stove-heater will simultaneously warm the water in the tank – you can not only steam, but also wash.
Metal stoves allow combustion of any type of solid fuel, it can be wood, coal or peat.
Higher efficiency than brick ovens – 80-85% for metal ones, 75% for brick ones. The high heat transfer of metal furnaces is due to the fact that their surfaces are heated to higher temperatures than that of brick furnaces.
An undoubted advantage will be a simple scheme for installing the stove in the bath – the small size of the metal stove allows it to be placed in a steam room for one or two people, does not interfere with bath procedures.
Disadvantages of a metal furnace: high temperature of heating of the walls, which leads to hard radiation of heat and can lead to burns if accidentally touched; low heat capacity, due to which the heating of the body of the steamed people is uneven; incomplete heating of the heater filler allows you to get only raw steam, typical for a sauna, but not for a Russian bath.
We increase the heat capacity of a metal stove
It is possible to improve the heat capacity and increase the humidity in the steam room by lining a metal stove with refractory bricks on its sides – a kind of hybrid between a sauna and a Russian bath is obtained. The laying is carried out in half a brick, the binding in the masonry mortar, as in the laying of any stove, will be clay. If you wish, you can completely close the metal furnace with brickwork, the walls of which are not erected close to the furnace (otherwise the metal will quickly burn out), but at a distance of about 15 cm from its walls. If the stove is placed in a brick “sarcophagus”, the overlap is placed on top of metal corners, and on one of its sides doors for air intake and outlet are installed, placed above and below, at the level of the heater – a door for filling water.
A stove improved in this way must be heated longer than an ordinary one – about 3-4 hours.
How to position the stove in the bath
It is widely known that for ease of use and fire safety, heating boilers, for example, are placed in a separate room. If the metal stove-heater is completely placed in the steam room, this will create several problems: the dressing room will practically not be heated; according to the rules for installing the stove, the space around the firebox must be protected by a sheet of metal, which will create inconvenience for the visitors of the bath; a continuous oven will require periodic fuel filling, which interferes with the visitors of the steam room. Therefore, the optimal scheme for installing the stove in the bath is as follows – in the wall between the steam room and the dressing room, an opening is made somewhat larger than the dimensions of the fuel channel, which is inserted into it. It should be noted that most of the factory models of stoves-heaters have a fuel channel protruding in front of the main body and designed just for output to the dressing room.
Most often, the installation of the stove in the bath is performed on one side of the doorway to the steam room. If the internal partitions in the bath room are made of combustible material, then the opening for the fuel channel and the section of the wall in which this opening is made and which is located directly behind the body of the metal furnace must be sewn up with asbestos cardboard, on top of it – with a sheet of metal at least 4 mm. The minimum distance from the furnace body to walls and partitions, unprotected by asbestos and sheet metal sheathing – 320 mm, protected by sheathing – 260 mm. When installing a metal furnace and installing a chimney for it, you must follow the rules given in SNiP 2.04.05-91.
Before actually installing the stove in place, it is required to build a supply and exhaust ventilation. The fresh air duct is mounted below the floor level and is supplied to the installation site of the metal stove; it is allowed to place a ventilation hole under its bottom, provided that the stove body is equipped with legs that raise it above the floor level. Supply channel section – 100 cm2, the opening at the entrance to the steam room is taken with a metal grate. The exhaust duct is organized in the farthest point of the steam room in relation to the position of the furnace, its opening of the same section as the inlet one is cut in the wall under the ceiling, just below its plane. The exhaust opening is equipped with a vertical hood box, taken in by a metal or plastic grate. For the convenience of controlling the supply and exhaust ventilation, its openings must be equipped with manually adjustable valves.
The foundation for a metal sauna stove is not required, because its weight will not exceed 700 kg, but a prepared base placed on a combustible floor surface is necessary. In the first version, sheathing of the site under the furnace with sheet asbestos with a thickness of at least 10 mm, on top of which a sheet of metal 4 mm thick is attached. In the second version, a platform laid out of bricks “in a quarter”, covered on top with a metal sheet or concrete screed. In both cases, the prepared site should be twice the area of the base of the metal furnace..
The chimney, as a rule, is not included in the complete set of the heater, it must be purchased additionally. The fewer bends it has, the better – ideally, the chimney should be completely straight, without bends. When considering how to position the stove in the bath, do not lose sight of this condition for high-quality stove operation. The minimum length of the chimney is 5 m, the length is calculated from the level of the grate, its diameter must correspond to the diameter of the outlet from the furnace. The chimney must be equipped with a damper.
If the stove of your choice runs on natural gas, then a chimney without insulation, similar to a conventional kitchen hood, is suitable for it. If the stove runs on solid fuel, you will need a special insulated chimney, described below.
Important: The outlet of the chimney through wooden ceiling slabs must be made through the ceiling-through unit, otherwise a fire cannot be avoided!
When burning wood fuel, incandescent furnace gases that rise through the chimney heat the metal forming it to high temperatures – with direct contact or close proximity of the chimney with the wood of the ceiling, the wood will heat up, smolder, then flare up. To prevent such a scenario, a metal ceiling throughput unit is required – a sheet of stainless steel, on which a square or round metal bunker is fixed, in its center there is a hole for the diameter of the chimney. Slag, expanded clay are poured into the bunker of the passage unit, after passing through its opening of the chimney, or basalt wool is laid.
From the middle of the bunker tank of the ceiling-throughput unit, the chimney must be insulated to its very top, in order to avoid condensation deposits on the inner walls. Ideally, the pipe should be lifted with pre-insulated sandwich modules. The chimney for metal heaters must be thin-walled, otherwise its weight will have to be additionally compensated for, because the design of the furnace will not withstand it. If the roof of the bath is covered with a combustible material, a spark arrester made of a metal mesh with a cell of 5 by 5 mm must be installed inside the chimney near the end. Minimum chimney height: above a flat roof – 500 mm; above gable and other roofs – 500 mm above the level of the roof ridge.
How to choose a metal stove
The choice of a stove begins with calculating its power, if according to a simplified scheme, then one kilowatt per cubic meter of the pair room. This calculation only works if the steam room is perfectly insulated, which is extremely rare – ceramic tiles, brick walls, glass windows and doors perfectly absorb the heat generated by the stove. A complete calculation can only be performed by a specialist, but usually it will be enough only to add two additional kilowatts to the power calculated by the volume of the steam room. Do not choose a stove with excessive power, because in this case, it will not be possible to create the necessary microclimate in the steam room.
When choosing a stove for a bath, pay attention to the structures equipped with a furnace-tunnel – the scheme of installing the stove in the bath in this case will not cause inconvenience to the visitors of the steam room. Make sure the tunnel firebox is wide enough and rigid.
Be sure to find out what is the heat resistance of the metal from which the furnace is formed. The heat resistance of steel is determined by the content of chromium in it – its ratio in the composition of steel should be from 13%, in this case the metal walls of the furnace can be thinner, but not less than 2 mm.
The capacity of the sauna stove with which the sauna oven is equipped is determined according to the following principle – 3-6 kg per cubic meter of the steam room. The optimal size of the stove filler is about the size of a fist, in this case the stones will effectively absorb the heat radiation from the stove. Stones of unknown origin cannot be used, because it is not known what substances will be released by them when heated. Porphyrite, basalt, peridotite, talcochlorite, gabbro-diabase and jadeite, which have good heat capacity and a complete absence of toxicity, are suitable as fillers for the stove..
The efficiency of the furnace depends on the volume and length of the fuel chamber – the more these parameters are, the higher its productivity. The grate of the grate should only be made of cast iron, because only this alloy is able to withstand high temperatures.
Inspect the ash chamber in the blower – if it is equipped with a drawer, this will greatly simplify ash removal.
On the Russian market of metal stoves, there are products of both foreign and domestic manufacturers, and domestic metal stoves are often in no way inferior to imported ones at a lower price – a Russian stove will cost on average 11,000 rubles, the average import price will be 22 000 rubles (the price depends on the model and its capacity). It should be noted that in addition to the furnace itself, you will need to purchase a chimney kit, sold separately – it will cost about 3,500 rubles.