Vacuum radiators: device and principle of operation,

In pursuit of increasing the efficiency of heating devices, manufacturers in addition to traditional iron and steel began to use copper and aluminum in the manufacture of radiators. Later, the idea came to create a vacuum battery - due to the clever design of such a heater should instantly warm up, and its power can exceed the best bimetallic counterparts. At the same time, it can be both mobile (it is enough to plug in electric vacuum radiators) and flow-through (it is connected to the heating system).

Device and principle of operation

The key difference between a flow-through vacuum radiator and a conventional radiator is that the coolant in it only moves through the bottom (the pipe passes through the bottom of the heater). In a classic cast iron radiator, hot water is usually supplied from above and passes through all sections, heating the metal.

In vacuum devices for heating the surface, a slightly different principle is used:

• a heating pipe with hot water heats up to boiling the liquid pumped into the radiator at the factory;
• then this liquid evaporates and rises to the top of the sections;
• it cools and condenses on the inner surface of the walls. The fluid under the action of gravity moves to the bottom and the cycle repeats.

The use of ordinary water would lead to an increased consumption of energy for its evaporation, therefore, these batteries use a special light-boiling liquid. As a rule, lithium-bromide liquid is used in order to reduce the energy required for its evaporation, air is pumped out of the battery. Due to this, the boiling point is reduced to 35?

Note! Lithium-bromide liquid can not be called beneficial to health, therefore, if a radiator leaks, its operation should be stopped immediately.

The described principle of operation of vacuum heating radiators is used in any and all heating devices of this type. Only the composition of the liquid, the operating temperature (depending on the composition of the liquid), and the appearance of the device can change.

Advantages and disadvantages

Theoretically described design is devoid of serious flaws.

The advantages of manufacturers usually include:

• high heating rate (usually in seconds);
• guaranteed absence of air traffic jams - they simply have no place to form, because the coolant passes through 1 pipe;

• the amount of coolant in the heating system should not be too large. 10-15 liters is enough, because the boiler does not work all the time, it will spend less energy for heating water;
• manufacturers also claim that vacuum radiators have increased heat dissipation compared with conventional radiators (this will be discussed further);
• uniform heating;

• low hydraulic resistance.

Among the shortcomings it can be noted:

• high cost, the price is several times higher than the cost of conventional radiators;
• the effectiveness of devices of this type strongly depends on the temperature regime. For example, when the temperature of the coolant rises above the recommended value, the low-boiling liquid completely changes to a gaseous state, due to which the heat transfer from the radiator drops tenfold. Hot water simply passes through the pipe and heat is not transferred through it to the walls of the battery.

Note! For a centralized heating system, vacuum batteries must be selected taking into account exactly what the supply temperature is.

More about vacuum heaters

Despite the fact that manufacturers say a solid set of advantages compared with conventional batteries, vacuum analogues are not yet so widespread. Among the main reasons for this can be identified not only the high cost, but also the lack of meaningful statistics on their use.

Whether promises of manufacturers correspond to reality

The manufacturer of any product seeks to emphasize the advantages of its product and modestly keep silent about its weaknesses. In the case of vacuum radiators, the story is the same; the whole question is how far reality is from theory and advertising leaflets.

We can single out such features of vacuum batteries, which the sellers are silent about:

• The battery is only an intermediate, whose role is simply to transfer energy from the boiler to the house. Accordingly, the heat transfer can not increase only because the air is pumped out of it and filled with boiling liquid, the battery is not a power generator, and does not produce anything by itself;
• vacuum radiators do warm up much faster than thick cast iron batteries. It just doesn't make much sense, it still takes more than an hour to warm up the standard room. So winning in a couple of minutes is absolutely insignificant;

• true and the complete absence of air traffic jams. But in conventional batteries this has long ceased to be a problem. Simply install the Mayevsky valve at the top of the heater and the excess air can be drained independently;

Note! To do this, you also need to ensure the correct slope of the radiator during installation. He leans a little so that all the air is collected in the upper part, at the tap.

• corrosion and clogging of the vacuum heater is also impossible - the reason lies in the fact that the coolant does not circulate through the battery sections themselves;
• There may be problems in autonomous heating systems with natural circulation. The fact is that in them the coolant moves due to the difference in height between the boiler and the battery itself. Compared to a conventional heating system, the height difference will be less by the height of the battery, respectively, the pressure in the pipe will also decrease;

• as for hydraulic resistance, it is really small, but for the host this parameter is absolutely not important. This indicator has a significant effect only for companies engaged in servicing heating systems;
• vacuum radiators in the autonomous heating system require a small amount of water in the system, but the boiler will have to be switched on more often in order to maintain a constant temperature. So this parameter also cannot be called the indisputable advantage of vacuum devices over conventional ones. In addition, modern radiators also cost a relatively small amount of water;
• in the description it is usually said that the radiator works even at a low temperature of the coolant, this is true, but the heat transfer is also low. Therefore, in order to achieve a comfortable temperature in a house with a low-temperature heating system, it will be necessary to increase the heat transfer area (that is, simply to buy a larger number of expensive heaters);

• It should also be recalled that the liquid in the battery is far from harmless. And if a leakage of a conventional battery threatens only a small damage to property, then a leak of lithium-bromide liquid and its evaporation will affect the health of residents.

Subtleties of choice

Given all the described features of the work of vacuum radiators, it is difficult to recommend them for purchase. And the point here is in the high price, the efficiency is not much higher than that of the same bimetallic heaters, and you can get a lot of problems.

Nevertheless, if there are no problems with finances, then it is possible to purchase such a battery, you just need to make the right choice.

The selection instructions are as follows:

• First you need to familiarize yourself with the temperature of the device. if it is designed for a coolant temperature of 110-120? C, and it is planned to install it in a regular city apartment, then you can forget about the declared performance;

• then pay attention to the appearance, in particular the quality of painting. The paint should not be rubbed off with a fingernail, be evenly applied to the metal surface, and should not have any smudges and flows. Poor quality paint suggests that this radiator is likely to be of poor quality;

• the liquid inside should not be too much. It is enough just to tilt the battery and listen - light rustling means that everything is in order, gurgling indicates that there is a lot of liquid;
• welds should be clear, smooth, without sagging.

Homemade vacuum heater

It is really possible to make a vacuum radiator with your own hands. All that is needed for this is an old conventional battery and a volatile liquid. It is undesirable to use water, as the efficiency of the heater will decrease.

The assembly is performed in the following sequence:

• a pipe with a heat carrier will pass through the lower channel, so the plugs are removed at the bottom of the pipe, the pipe is inserted, the joints are sealed;

• in the upper part of the radiator you will need a hole to fill it with a low-boiling liquid. Alcohol can be isolated from the available analogues of lithium-bromide mixture, it evaporates fairly easily and is harmless to humans;

Note! Up to the stop it is not necessary to fill the battery, it is enough that the liquid covers the pipe with the coolant.

• after this, the most difficult part is air pumping. Without a compressor, this will not work;
• you will also have to do the calibration of the device yourself in order to identify the optimal operating conditions. It is possible to increase the temperature of the coolant by 5-10? С and measure the surface temperature of the battery for each new value.

Instead of a flow-through tube, a heating element with a thermostat can also be inserted. In this case, we obtain a universal device that can be used as an addition to conventional heating.

Summarizing

Vacuum heating radiators are an interesting idea that requires serious research. So far, the effectiveness of such heaters can be judged only by reviews of rare owners, but by advertising manufacturers. In the future, subject to lower cost, they can be considered as analogous to conventional radiators.

The video in this article shows the principle of operation of such heating devices.