Recently I saw a video where the master was winding a spiral from a copper tube for a home refrigerator with a tricky name. The instantaneous water heater can also be made independently. The pipe bends excellently. The length of the nichrome spiral can be halved. The current will increase, therefore, and the power will be allocated more than twice.
We make a flowing water heater
out of nichrome It seems a paradox - we reduce the length of the spiral, and more power is released. There is a logic - the small is not strong. Let's watch. The thermal effect according to the Joule-Lenz law is equal to the product of voltage and current. The first value is constant( this is an ideal case, but for apartments it is approximately true), the second parameter is regulated. We double the current, we get twice the power. Try to remember when traffic jams burn out. When do we turn on the long helix? Yes, power 2 kW.Here it is already intuitively clear that not enough.
Developers calculate the thermal mode of operation of nichrome wire and take the amount that can work for a long time. It is necessary to satisfy the conditions of energy dissipation through the surface bounding the helix.
Reducing the number of turns by 2 times, we get 4 kW, the shield is broken, the bugs fly out, the light goes out. Eureka. Why do “stupid” constructors sometimes make two spirals of 2 kW each, instead of reducing the number of turns? Let's watch! Heat losses depend on temperature differences between the surface and the medium. A power increase of two times is equivalent to a double increase in temperature. But the surface of the scattering was less than half, it turns out already 4. If it was 200 degrees Celsius, it will become 800. At this temperature, the aluminum becomes a liquid.
Due to temperature conditions it is not recommended to make too powerful spirals. Nichrome temperature keeps well, but burns in the air. Take the nichrome wire and make a 6 kW instantaneous water heater, but with three spirals, so that the fire does not come out and the device works properly. Along the way, we calculate the approximate size of the device. Why is the copper tube taken as a core? Due to the high thermal conductivity of the material. The lion's share of energy goes into the water, not into the air.
Calculation of the instantaneous water heater
Let us skip the theoretical calculations with the calculation of the capacity of the instantaneous water heater, it is known that 4 kW is enough for a water flow rate of 5 liters per minute, and the jet is not hot. So, 6 kW is enough for a normal shower. We warn the people living in old houses, that 6 kW not each electric guard will pull. For details, consult your local electricians. For buildings below 9 floors, a limit of 5 kW applies. In the Khrushchev, given the old wiring, it will be even worse.
Decide how much power a flow heater is needed, but 4 kW for a device is a modest indicator. For comparison, 2 kW is used as a washbasin, where water flows in a comparatively poor trickle. For washing, be guided by those 5 kW serving as restriction of a guard of the typical apartment. What to take a copper tube? We answer the last thing, having figured out how many turns to wind and the total length of the wire from nichrome. We propose to do this:
- Twist a ring of four turns of a copper tube. And in the cross section will be located square. It doesn’t matter where to do the taps;Vertically or horizontally fasten - there is no difference.
- We wind spirals on the tubes, there are three of them. Turn to turn, step by step and tight. Do not use glue, at the edges grab heat-resistant composition. This will ensure fixation. Just find online glue( suitable for stoves), suitable for metal.
- A heat-resistant fabric should be laid over the helix. It is difficult to find it, in case of impossibility just make installation so that no combustible materials get on the spiral. It's easy enough to do.
- The feeding of the spirals is parallel. Otherwise, the power of the device will be low. Each spiral put an individual switch to adjust the power.
Go to the choice of material. Let's start with the copper tube, choose the length of the last. The resistivity of nichrome is 1.1 Ohm mm2 / m. Make no mistake in the calculations. Let's give an example. In the hardware store a nichrome wire cut with a diameter of 1 mm was strayed. Calculate the area of the known formula. Square the radius, we get 0.25.Multiply by pi, it comes out approximately 0.8 mm2.We divide the initial resistance by this number, it turns out 1.4 Ohm / m. For each helix, find 25 / 1.4 = 17.84 meters.
The device of the instantaneous water heater consists of three spirals, each 17.84 meters. Choose a tube with a diameter of 10 mm with a wall thickness of 1 mm. The square of the tubes will have a perimeter of approximately 8 cm. Divide the meters by 1 turn to find out the length of the winding. It turned out 223 turns, which will be 22.5 cm along the inner circumference. So, you need to roll the tubes with an inner circumference of 80 cm. We find the inner diameter of the bend is 26 cm. So, the construction will take about twenty meters of the tube. In the worst case, 200 rubles will be released.
We believe there is no need for welding, the tube has zero chances to reach 150 degrees Celsius. If there is a burner( like a refrigeration master), use. It is ideal to find a master in air conditioning, which will flare the ends and put it on the nut( in the air conditioning technology we use the likeness of an American).Such a connection is easily assembled and fit in with other plumbing fixtures( using a nipple).
The principle of the instantaneous water heater is based on the Joule-Lenz law. We add that the safety elements in the design is not available. Use the product carefully.
You must open the water, then turn on the heating. The temperature is governed by the force of the jet and the number of included spirals. Note that the stronger the flow of water, the lower the temperature. Do not be afraid of hot water, trying to close the tap, it will aggravate the matter. On the contrary, open the valve, let the boiling water drain into the sewer and wash. The device will work briskly, control devices will be needed. A bimetallic plate from an oil heater will do.
The knob adjusts the switch-off temperature of the spirals. Connect the phases of the spirals through a bimetallic plate, or two of them, for an excellent result. It is necessary to choose the settings. If it is not possible to set the correct parameters by attaching the bimetallic plate to the tube, make it heat-resistant ceramics, it will lower the temperature on the surface. This method will select the required parameters. Follow the homemade instantaneous water heater is not necessary.
The parameters for a self-made design vary widely. It should try two spirals, maybe enough. And now about energy. Gas flowing water heater on the structure will give more heat. We talked about a wood-burning water heater for the pool, which develops a power of 20 kW, and he showed that coal is more profitable than gas. Of course, wood is the undisputed leader. Gas is free if the limit is paid at the tariff without a counter. In this sense, the electric instantaneous water heater is inferior to the gas.
Electric is safer and easier to set up. Simply ground the copper tube more reliably, and the self-made instantaneous water heater will serve for a long time and correctly, giving a warm stream when necessary. Replace the temperature controller. Assemble the instantaneous water heater from a bimetallic iron plate. The difference is that it will most likely be strengthened against nichrome( or through refractory fabric).We have shown how to make a instantaneous water heater, but do not forget that officially no service will allow to put such a good thing in residential premises. And, by the way, our homemade device should be beyond the reach of water.
