Do-it-yourself metal stove for a bath

Recommendation points

• What, what and how to cook a stove for a bath
• We dissolve the sheets: drawings and dimensions of parts
• Furnace manufacturing
• Base and heater
• Sheath or cover
• We complete the installation: firebox, ash pan and chimney

Assembling a heater for your bath yourself is a very bold and responsible decision. However, there is no need to invent anything new. Let’s take a closer look at the design of a heater with dry steam, select the material and determine the optimal order of work..

For example, consider one of the typical designs for dry steam and supplement it with a remote firebox, a convenient ash pan and an additional heat exchanger.

What, what and how to cook a stove for a bath

Structural steel exhibits exemplary strength and toughness at normal temperatures, but not in a wood-fired oven when heated above 400 ° C. All processes, chemical and physical, in heated steel are accelerated a thousandfold: the formation of scale, carbon burnout, thermal fatigue, and linear deformations. Bottom line – choosing heat-resistant steel for a high temperature zone is not so easy.

There are two ways to solve the problem: increasing the metal thickness over 12–14 mm to increase the life of the furnace, or using steel with a high (over 18%) chromium content. The latter is often difficult due to the need to own MIG / MAG or TIG welding in order to connect parts, as well as due to the low availability of special rolled metal. But if there is an opportunity, choose a heat-resistant AISI-310S for the furnace (its analogue 20X23H18) in annealed sheets 6–8 mm thick.

There is another, quite effective solution that helps to reduce corrosive wear – cooling the bottom of the furnace with a water circuit or air convection. Heat exchangers included in the design of the furnace must be made of the same steel. All other elements: neck, chimney and body, can be welded from structural carbon steel with ordinary rutile-coated electrodes.

But with a firebox, it is more and more difficult: parts should be welded with a non-consumable electrode using a flux additive containing sulfur and titanium in an intermediate form. Perform a couple of experimental welds on cuttings of the same thickness beforehand to establish the minimum welding current required. The weld pool is protected by argon at a feed of about 7 m³/ h In the absence of special types of arc welding, parts of conventional MMA can be welded using OK-67.13 electrodes (15).

We dissolve the sheets: drawings and dimensions of parts

First, let’s decide on the size of the firebox. A chamber wider than 300 mm will be too spacious for the concentration of the temperature center above 450 ° C, and without this, the combustion of pyrolysis gases (and the efficiency of the heater) will be less than expected. The length of the firebox should be sufficient for storing logs over 300 mm, in total – about 750-800 mm. The height of the furnace must correspond to the firewood flame – at least 650 mm. Also, the volume of fuel loading depends on the height, proceed from the calculation of 1.3-1.5 kg of dry firewood per 1 m³ steam room.

Based on this, we cut out four rectangles:

• 650×800 mm – two side walls;
• 300×500 mm – furnace cover;
• 300×650 mm – front and back walls.
• 290×400 mm – internal partition.

You will also need two rectangular slats 50×580 mm and a dozen scarves in the form of an isosceles right triangle with a leg 50 mm.

The next question is furnace cooling. If air convection is planned, weld on the back and side walls vertical ribs 45 mm wide and lengthwise along the height of the firebox every 80 mm, for a total of 24 pieces.

Water cooling allows the use of thinner steel (4–5 mm), but the heat exchanger must be included in the heating or water treatment system with a total heat capacity of at least 65 liters for a warm floor and 150 liters for a tank. The heat exchanger is manufactured with a welded box up to 70 mm thick along the rear and side walls of the furnace. You will need:

1. Two side walls – 350×880 mm.
2. Back wall – 350×440 mm.
3. Strip 70×885 mm (4 pcs.), 70×360 mm (2 pcs.) And 70×300 mm (2 pcs.).

In addition, you will need about three meters of angle steel 50×50 mm, up to four meters 75×75 mm and up to 0.5 m² sheet carbon steel 3.5–4.5 mm thick. When cutting parts, chamfer a third of the metal thickness on both sides.

Furnace manufacturing

On the side walls we mark 50 mm from the bottom, along this line you need to set perpendicularly and grab strips 50 mm wide, then from the bottom with a distance of 100-150 mm set and weld triangular scarves, six on each wall. Lay 2-3 grates 300 mm wide on the shelves obtained, and cover the remaining gap at the back wall with a sheet of stainless steel.

Next, flip the walls over to the top edge and mark 300 mm from the back. Install and grab the partition, check the perpendicularity of the inner corners, the diagonal of the walls and weld the two vertical seams completely. When welding parts of the firebox, first lay the root seam on the inside, and then cover it with two protective layers from the inside and outside without deep penetration.

Install and weld the front wall with a continuous seam, and in the back, pre-cut a round hole with a diameter of 110 mm with an indent of 110 mm down from the top edge. Weld a sleeve from a black pipe into the hole, if welding is impossible, install a flange connection or twist a stainless steel strip into the pipe.

At the end of the assembly, a tank or air cooling fins are welded around the firebox. Do not forget to cut in diametrically opposite points of the water heat exchanger two pieces of stainless steel tube 25 mm with 4-5 turns of pipe thread.

Base and heater

The firebox is installed on a frame welded from the 50th corner with shelves inward. The inner perimeter must exactly match the dimensions of the bottom of the firebox. The frame stands on legs with a free clearance of 200 mm. If you do not plan to brick the heater, cover the bottom, back and sides of the base with thin sheet steel.

The same frame, but with shelves outward and made of 75th angle steel, is welded exactly along the upper girth of the firebox. Closer to the back, add one more lintel so that the inner side of the corner shelf fits snugly against the partition, forming a 300×300 mm square cell. A tank with dimensions of 250×250 and a height of 500 mm is inserted into this opening. Make it from sheet steel about 4 mm thick, 100 mm from the top edge on the outside, add an angle steel belt with which the tank will rest on the frame.

The resulting structure is installed on top of the furnace, scalded around the perimeter with steel sides about 150-200 mm high and filled with stones. The tank is used to heat the water, and the rest of the heater “catches up” the steam to the desired temperature. It is a good idea to run a pair of 3/4 ” pipes from the bottom of the tub to the bottom of the stove, with frequent 6mm holes in the sides. In this case, the tank itself must be covered with a lid, leaving a tube in the center – a water dispenser.

Sheath or cover

If you are using air convection, it is correct to wrap the oven in a thin sheet steel jacket. You can fix it to the frame from the 75th corner, and then repeat the fastening in the lower part, having previously welded on the firebox several “tongues” with holes and threads.

For water cooling, a casing is also appropriate, but it is better to overlay the heater with decorative bricks or sandstone. The masonry, like the casing, is brought out flush with the sides of the heater or slightly below.

We complete the installation: firebox, ash pan and chimney

After assembling the stove, mark and cut an opening on the front wall, sized for the existing fire door. Using the same dimensions, weld cuffs with a depth of at least 170 mm from stainless steel scraps or into the thickness of the partition if you take the door into the dressing room.

The ash-pan in such a stove is an ordinary box 250 mm wide, 200 mm high and the full length of the firebox. In the front part, the wall should be 50 mm wider than the box on both sides and 100 mm up.

The chimney can be pulled with a sandwich pipe or a regular steel duct. On the sleeve in the back wall we put on and seal the rotary knee with glass cord, then we caulk the corners of the base and the stove with the same cord, do not forget about the partition inside the firebox. After laying the stones, the furnace is ready for operation, but it is recommended to melt it outside before installing it to ignite and burn out the remnants of the factory rolling grease.