The designs of metal stoves are very diverse and include the use of industrial parts. The temperature rises quickly in them, which allows you to start bathing procedures within 30 minutes after the start of the furnace. The danger of carbon monoxide poisoning is excluded, since the furnaces are closed on all sides with metal, and the stones are heated due to the fact that hot gases give up their heat to the metal, and it, in turn, to the stone backfill.
All metal furnaces have a low heat capacity and do not create conditions for uniform heating of the body. In order to somehow reduce this negative property, they are faced with bricks on the outside, leaving a small gap for the air gap. By the way, this also reduces the risk of burns. To increase the service life, metal stoves are lined with refractory bricks from the inside of the firebox.
Heaters with integrated water tank:
a - heater with single walls
b - a heater with a side wall in the form of a water tank
c - a heater with a water tank and an air gap in the walls.
Metal heaters are made of 4-5 mm thick sheet iron. The water tank can be positioned on different sides. A special open thermal chamber is provided for the stone backfill. Such ovens are very economical. They heat up quickly but cool down quickly. It is difficult to achieve good steam 20-30 minutes after the end of the furnace. The designs of such stoves are often combined with stoves, which are installed in a room adjacent to the steam room. Hot gases, heating the stove, do not go into the chimney, but through a special outlet into the stove. In this case, special attention should be paid to ensure that all fire safety measures are taken into account in the place where flue gases pass through the opening in the wall (see Fig.).
The continuous metal stove-heater provides for the separation of hot gases from the stone backfill, which is heated through the surface of the steel plate. The furnace of this design can operate on any type of solid fuel.
Another stove-heater, suitable for both Russian and Finnish baths. This stove heats in the winter for 1.5 hours a steam room with a volume of 8 m3 to 80 ° С and the soap compartment of the same size up to 35 ° С. At the same time, 50 liters of water are heated almost to a boil.
You can steam without waiting for the oven to completely heat up. It has two chimneys: one is for stoking and heating the stove, the other is a bypass one for releasing smoke and carbon monoxide when the required temperature in the bath has already been reached, and the wood has not yet burned out.
The furnace is welded from sheet steel 3-5 mm thick. For ease of installation and transportation, the firebox, stove and pipe are made separately.
The firebox is a steel box with a 60 mm high neck for adding a stove. It is made of steel with a thickness of at least 5 mm. The set of the firebox includes two valves - a large and a small one, a heater grate and a blower grate.
The grill of the stove is welded from steel rods with a diameter of 20 mm with a distance of 50 mm between them and is freely installed on the supports, the grill of the blower is made of steel rods with a diameter of 8-10 mm at two corners of 20x20 mm with a gap between the rods of no more than 5 mm. This grill is also removable. Slots for valves 10 mm wide are welded from 5x20 mm steel strips to the entire width of the firebox. The groove for the dividing wall of the heater is also made of steel strips. A blower is welded from below.
The stove is made of steel with a thickness of at least 3 mm so that it fits freely on the neck of the firebox. The stove door is made on the side facing the steam room.
At the top, the stove has two nozzles with a height of 100 mm and a diameter of 140 and 100 mm with flanges welded to them with four holes for attaching a pipe and a bypass elbow. Chimney diameter 140 mm.
To reduce the size of the firebox, as well as to increase the mass and for fire prevention purposes, the side of the stove, which faces the wooden wall, is lined with brick on the edge.
When the stove is fired, only two valves are open - the large one and up to the flange on the pipe. Small closed. When the wood is almost burnt out or burns out, and the temperature is close to that which is optimal for you, you can enter the bath, open the small valve, and close the other two. Residual smoke and carbon monoxide will go through the second, bypass, channel, bypassing the heater.