- Tank placement method
- Open or closed tank?
- Features of the manufacture of the case
- Water jacket heater
- Installing a tank on a chimney and connecting it
It is very good when the heater copes with both the heating of the steam room and the preparation of hot water for the shower. We propose to discuss the design features of such a stove in order to understand how to assemble a heater with a water tank with your own hands and ensure its long-term and trouble-free operation..
Tank placement method
In order for the water to heat up quickly, the tank must provide effective heat removal. The reverse side of the question is that overheating and boiling of the liquid should not be allowed. Thus, the optimal place for placing the tank is determined by the equilibrium ratio of the degree of heating and the contact area. In view of the above, there are three suitable installation methods.
Option one – from the side close to the wall of the firebox according to the principle of a water jacket. The tank does not have to repeat the full size of the wall, due to the contact area and width, you can easily adjust the heating intensity and volume of the tank. The main disadvantage of side placement is associated with the fact that the most efficient heat removal is possible when the wall of the furnace is also the wall of the tank. Even a minimal air gap between the double walls leads to an increase in the heating time up to several hours, so it is necessary to select a steel grade with good weldability in order not to reduce the heat resistance of the furnace.
Option two– a cylindrical tank around the chimney. The main advantage of this type of tank is the minimum of “theft” of space in the steam room, which, as a rule, has a minimum area for quick and economical heating. The disadvantage of the tank is the relatively high complexity of its independent manufacture. A tank of this design is nothing more than an ordinary chimney segment: it is very simply connected to the exhaust duct of the stove by means of a swivel elbow or a short insert, while the cross-section of the inner pipe can be chosen by any, so there will be no difficulties with the selection of a suitable sandwich pipe.
And finally, third option– installation of the tank in the hottest zone, that is, directly on the stones. This design has the longest heating time, but it does not depend in any way on the design of the furnace itself. There is only one drawback here – if the tank is located on top of the masonry, this is:
- not quite aesthetically pleasing;
- causes inconvenience with adding water to generate steam.
Stoves with a closed heater will be most suitable for such a placement of the tank, however, the capacity of the water heater should be chosen taking into account the reduced heat transfer.
Open or closed tank?
One of the main subtleties when arranging a tank for a bath stove is to determine its mode of operation and purpose. It often makes sense to combine the preparation of hot water for water procedures and take part of it as a heat carrier for the heating system of adjacent rooms.
The suitability of the tank for multifunctional use is determined by its type, it can be closed or open. A closed tank is a sealed container into which water enters under operating pressure from a cold water supply system. Such a tank has no danger of overflow, but at the same time it remains extremely sensitive to overheating and requires the installation of a safety group with a relief valve..
An open tank does not have a top sealed cover, plus it is not always suitable for connecting to a heating system. Control of filling or installation of a float dispenser is required. But there are also advantages: an open tank is completely safe, its boiling will not turn into a tragedy, and therefore a careful calculation of the volume and taking into account the heating intensity is not so important.
Which option is better? At a minimum, this is determined by the filling method, since it is almost impossible to fill a sealed tank with water manually. In turn, a closed container is more convenient during operation: there is no need to monitor the water level, the full volume of the heated liquid can be consumed at your own discretion, without fear of emptying and air entering the heating system circulation pump.
Features of the manufacture of the case
It is best to choose stainless steel sheet with a thickness of 1–1.5 mm as the material for making the tank. The heat resistance of such a design is not so important, the ease of processing at home is much more critical. That is why steel grades with a low carbon content and alloying chromium, which can be modified to carbide when the weld seam overheats, is optimal for the manufacture of the tank..
For the manufacture of a tank, steel grades AISI 304L or the more common 07X16H6 are best suited. With such a small metal thickness, the weld seam is very easy to burn through, therefore, it is recommended for novice welders to use OK61.30 electrodes with a thickness of 2 mm; for more experienced craftsmen, cheaper OZL-8 or TsL-11 with a 3 mm rod are suitable. Welding is carried out by an inverter in reverse polarity (plus on the electrode) at a current value of no more than 50-60 A.
To connect thin sheets, it is recommended to overlap them with an overlap of about 10 mm. The seam is performed in one pass without lateral vibrations and at a sufficiently high speed. To ensure rapid heat removal from the welding zone, it is advisable to place a massive metal object on the back of the seam: for flat seams it is a metal plate or channel, for corner seams – angle steel, for a connecting seam of a cylinder – a pipe with a diameter of 70-80 mm.
A tank in the form of a parallelepiped is assembled most simply; it is enough to make an integral sweep of the vertical walls and bend it into a rectangular sleeve. The bottom and lid of the tank are rectangular fragments, the edges of which are bent outward at a right angle. After insertion, these parts are positioned so that the tank wall protrudes 3-5 mm beyond the folded edge, then welding is carried out along this joint. In this case, the electrode should be directed not perpendicular to the plane of the metal, but at the end of the bent fragment at an angle of about 60 °.
A tank for installation on a chimney can have cylindrical or rectangular outer walls, but in this case, it is imperative that the pipe be pre-fabricated according to the inner diameter of the furnace exhaust outlet. In some cases, this pipe is made a little conical (in the upper part, the overlap is 1–1.5 mm less) in order to be able to tightly insert it into the outlet of the furnace and ensure its equally tight connection with the upper segments of the chimney. In any case, to make a pipe, you will need to roll up a steel sheet and straighten the edges by 10-15 mm on each side to be joined to obtain tight seam planes.
First, the pipe is attached to the welding table at both ends with clamps and welded from the inside. For convenience, the electrode can be inserted into the holder in a longitudinal position and slightly bent at 90 ° with a significant bending radius so that the coating does not fall off. After welding, an external sealing seam is made from the inside. Further, the technique is simple – weld the outer wall of the tank using one of the methods described and insert fragments of the bottom and lid with bent edges, weld all joints hermetically. It must be remembered that the pipe should protrude from the bottom of the tank at least 150 mm, from the top – about 50 mm.
Water jacket heater
Most types of heaters, including home-made ones, can be equipped with a side-mounted water tank. The exception is brick-lined ovens: often it is quite problematic to carefully dismantle part of such a screen..
If the heater screen is made of a steel casing, a window is marked on it according to the size of the tank. Then, in the casing, cut out a fragment less than the markings 15–20 mm on each side and remove the thermal insulation, if any. The indent from the marking forms a strip at each edge, which bends inward: you only need to make oblique undercuts in the corners, and then insert a block of suitable thickness between the body and the furnace screen, after which the board is recovered with a mallet.
The most difficult task is to make a high-quality welded joint of the tank walls with the furnace body. In this case, you need to choose the right material – for carbon steel furnaces, the tank must also be “black”. Welding must be carried out in soft modes so that, on the one hand, not to disturb the structure of the furnace walls, and on the other, not to burn through the metal of the tank walls.
It is most beneficial to temporarily disassemble the masonry and lay the oven on its side to weld in the lower position. You should not weld the tank to the stove with the walls at the end, it would be more correct to bend their edges 10-15 mm and lead the seam along the edge of the overlap obtained.
Installing a tank on a chimney and connecting it
As already mentioned, a tank on the chimney pipe is the simplest option that does not require a change in layout. The only limitation is the weight – a container with a volume of more than 50-70 liters requires additional support. For example, it can be suspended from the ceiling by chains or equipped with support legs..
The connection between the heater and the furnace is carried out “by condensate” – the tank pipe is inserted into the exhaust duct. To prevent undercutting in this place, a heat-resistant silicate sealant can be used. If the combustion products removal system on top of the tank is made with insulated sandwich pipes, the assembly of subsequent segments is carried out “by smoke”, for single-wall pipes it is recommended to adhere to the opposite direction of the connections.
Open tanks may not have a plumbing connection as such; it is enough to embed a ball valve in the lower part of the side wall. If the tank is flowing, two nozzles are cut into its bottom – one long, up to about the middle of the tank height, intended for supplying cold water, and one short for taking hot water. Many will rightly notice that this scheme is arranged according to the opposite principle than in storage water heaters, however, the furnace tank heats up not at one point, but over the entire height, therefore, cold water should be mixed in the most heated zone. If the tank is connected to the heating system, a cut-in of one more short threaded branch pipe is required for the return flow.