Resistant to high pressure or its differences
As you know, in multi-storey buildings, the coolant is supplied under high pressure, and pressure drops in the central heating system are not uncommon, and sometimes water hammer occurs. According to the rules, the supply of hot water by circulation taps should be carried out smoothly. But there are times when these requirements are not met, as a result of which the pressure in the system jumps, leading to the fact that the batteries cannot withstand the load.
- Cast iron radiators at a stable pressure can withstand 9-12 atmospheres, but in the event of a strong water hammer, cast iron may not withstand, since the material itself is brittle and non-plastic
- Bimetallic withstand 20-25 atmospheres, which allows you to transfer and water hammer. Monolithic bimetallic radiators with a steel inner core are capable of withstanding a pressure of 100 atmospheres, so the problems associated with sudden drops disappear.
As we can see, according to this criterion, bimetallic radiators win
Coolant quality
Hot water in the central heating system supplied from pipes is not clean and chemically neutral; it also contains small pebbles, rust and scale, which carry an abrasive effect.
- Increased alkalinity or acidity of hot water does not affect cast iron in any way. Such radiators, due to thick walls, can withstand corrosion for a long time, for example, in the summer, when the water is drained. But the abrasive elements in the coolant can gradually abrade the metal from the inside, but due to the wall thickness, this effect is insignificant.
- Bimetallic radiators are also not very susceptible to the chemically active composition of the coolant. But if the water is drained, air appears in the radiator, as a result of which the steel core may begin to rust.
From the above, you can see that cast iron radiators tolerate corrosion better.
Features of the functioning of the central heating system
Requirements for heating devices are formed by the operating heating system. As a rule, most apartments in Russia are served by central systems. Therefore, it is necessary to choose devices whose technical characteristics coincide with the parameters of their operation.
Here are the main ones:
The central system is a complex of equipment operating in a closed circle. The central heating unit produces heat, which is then transported through movable highways. To ensure transportation, forced circulation is used. Pumps create pressure, which helps to deliver the coolant to each apartment. Its indicators are different everywhere, but experts note that, on average, heating devices must withstand a pressure of 16 atmospheres.
When choosing radiators, it must be taken into account that the coolant pressure is not constant. It can significantly decrease or increase, forming dangerous water hammers. Therefore, the material from which the batteries are made must be durable and reliable.
Any radiator must function in conditions of frequent filling and draining of the system.
There are also frequent violations in the conservation of the central heating system, which are carried out during the summer periods.
They should not become the reasons for the failure of radiators.
And one more important circumstance. Given the percentage of depreciation of existing equipment, the poor quality of the coolant cannot be discounted.
In the hot water supplied by the central system for heating apartments, there are special technical impurities, debris and rust. The former reduce heat losses during the transportation of the coolant. And the second quickly clogs the risers and the inner body of the radiators
Heating appliances must cope with this difficult task.
It is also useful to take into account the features of the strapping of apartments and the materials from which it is made. As a rule, most engineering accidents occur due to poor compatibility of metals and materials with which selected batteries are connected.
We make a choice of cast iron or bimetal heating radiators
What is better, bimetallic or cast iron radiators? Bimetal is better. To verify this, it is enough to conduct a comparative characteristic of cast-iron and bimetallic heating appliances.
- The thermal efficiency of bimetallic radiators is four times higher than that of cast iron counterparts.
- The ability to withstand hydraulic shocks and resist the aggressive environment of the coolant is approximately the same. But with a sharp jump in pressure in the system, up to 15 atm., The cast iron will crack, and the aluminum-steel structure will withstand without loss of performance.
- Correspondence of sections of radiators. The thermal power of one "rib" of a cast iron product will be 100-160 W, compared to 150-180 W for a bimetal.
Replacing cast iron radiators with bimetallic ones is a justified and expedient solution. Although the cost of the latter is somewhat higher, the material costs will pay off due to the high heat transfer.
When performing work, the heating area is recalculated during the alteration. In the apartment it is forbidden to connect devices with a higher heat output to the heating system than indicated in the project documentation. So, if the room was heated by two cast iron batteries with 8 sections, when replacing it will be necessary to install two bimetal heaters with 6 ribs each.
For an apartment building, aluminum-steel batteries remain the best option. Connection of bimetal to autonomous heating systems is recommended in case of forced circulation of the coolant.
Radiators connected to a centralized heating system sometimes have to experience very high loads. Therefore, the only materials that can withstand high pressure and not collapse from corrosion are cast iron and bimetal (steel and aluminum). The latter in appearance resemble aluminum heaters. For the right choice of equipment, it is worth considering the characteristics of both in more detail.
Heat dissipation
- Cast iron batteries, due to the material from which they are made, heat up for a long time, but at the same time they cool slowly. The average thermal power of each section varies from 100 to 160 watts, depending on the model. Cast iron radiators, in addition to convection, also provide radiant heating, due to which nearby objects are also heated.
- Bimetallic radiators heat up very quickly and cool down quickly. Thermal power 150 - 180 W. The heating of the room occurs for the most part due to convection.
Conclusion: to quickly heat the room, of course, you should choose a bimetal. But there are situations when the heating can be turned off due to repairs or as a result of an accident - in this case, slowly cooling cast-iron radiators will still give off the accumulated heat for some time.
