So the heating season ended with grief in half, after which the question of changing the batteries came to the fore. Leaky ancient cast-iron radiators, it is time to send for a well-deserved rest, putting in their place something more modern. Private developers, when installing heating, also often can not decide on the type of radiators. Having listened to sellers in stores praising the most popular models, an ignorant buyer is at a loss. And which radiators are better - aluminum or bimetallic, he never imagines. Perhaps take a look at this issue objectively?
Let's start comparing bimetallic and aluminum radiators
What is each type of radiator
1. Aluminum radiators, neat and stylish, consist of several sections connected by nipples. Gaskets available between sections give the desired tightness. The ribs located on the inside allow you to significantly increase the area of heat transfer to 0.5 square meters. Radiators are made in two ways. The extrusion method gives cheap and lightweight products of not the highest quality (they do not use this method in Europe). More expensive but more durable will be cast radiators.
One type of aluminum radiator.
2. Bimetal radiators are made of two different metals. The case, equipped with ribs, is made of aluminum alloy. Inside this case there is a core of pipes through which coolant flows (hot water from the heating system). These pipes are made either from steel or from copper (the latter are almost never found in our country). Their diameter is smaller than that of aluminum models, so there is a greater likelihood of clogging.
The appearance of the bimetallic radiator is very aesthetic, and the design meets the most sophisticated needs. All its steel components are hidden inside.
What will give more heat - bimetal or aluminum?
If we compare the heat transfer, then the aluminum batteries will immediately rush forward. They have one section capable of producing more than 200 watts of thermal energy. Moreover, half of the heat is given in the form of radiation, and the second half - by convection. Thanks to the ribs protruding from the inside of the sections, the heat transfer is still increasing. So in this regard there is no equal to aluminum. Note that he also has minimal thermal inertia. I turned on the batteries - and after 10 minutes the room was already warm. In a private house, this allows good savings.
Consider now bimetallic devices. Heat transfer from one section depends on the model and the manufacturer. It is slightly lower than the all-aluminum radiator. After all, the core of steel helps to reduce the overall heat transfer, which can be one fifth less than that of an aluminum radiator of the same dimensions.
As for the method of heat transfer, it also includes convection and thermal radiation. And their thermal inertia is also small.
Aluminum + | Bimetallic -
On the ability to withstand high pressure (especially water hammer)
Then aluminum let us down - the numbers of its working pressure are not very impressive. Only from 6 to 16 (some models up to 20) atmospheres, which may not be enough to withstand pressure surges in central heating. But there will be no salvation from the water hammer - the batteries will burst, like empty nut shells, and there will be a big hot flood in the apartment. Therefore, do not risk it - aluminum radiators are not installed in high-rise buildings.
Bimetal models with a strong steel core inside are fully prepared for high pressure. From 20 to 40 atmospheres is quite good. Even if the crane at the pumping station is closed during an accident on the highway or is opened at lightning speed, they will not be damaged. It is bimetallic radiators that are most reliable at unstable pressure in the system when water hammer is likely to occur.
This parameter is important if you choose radiators for an apartment with a centralized heating system. If you choose these radiators for a private house, then this parameter is not a minus for aluminum radiators, since there is no excess pressure in the local heating network.
Aluminum + - | Bimetallic +
What is better bimetallic radiators or aluminum in relation to the coolant
Aluminum gladly enters into various chemical reactions, so for him the water in central heating is just a "treasure". After all, it contains so many chemical impurities that soon nothing can almost remain from the walls of the battery - corrosion will eat them. As soon as the pH of the hot water flowing in the system exceeds 8 units - wait for trouble. But with centralized heating it is impossible to keep track of this indicator. And in the process of chemical reactions, aluminum releases hydrogen, which is fire hazard. Therefore, it is imperative to constantly bleed air from such batteries.
Steel pipes in the middle of a bimetallic radiator are less demanding on the quality of the water flowing through them. After all, steel is not as chemically active as aluminum alloys. Corrosion, of course, gets to it, but not so soon. In addition, manufacturers cover it with a special protective layer. And sometimes they use stainless steel, but it's quite expensive. But in any case, the bimetallic radiator is more protected from too active chemically coolant. The only danger is oxygen entering this water. Then the steel will begin to rust, and very quickly.
Aluminum - | Bimetallic +
Maximum coolant temperature - which radiators have more?
The question is logical - often our batteries “burn with fire” so that you don’t touch it. So, aluminum can withstand boiling water up to 110 degrees - this is an average indicator. For bimetallic products, this figure is slightly higher - 130 degrees. Therefore, they win here.
Aluminum - | Bimetallic +
And what is more reliable, stronger and more durable?
And again, two-metal radiators break out into the leaders - after all, they combine the best qualities of each of them. Such devices serve about 15-20 years, no less (naturally, we are talking about a quality product of reliable brands). Their aluminum counterparts, as a rule, are distinguished by half the service life - up to 10 years.
Aluminum - | Bimetallic +
Which is easier to mount?
Both aluminum and bimetal are quite comfortable to install, as they weigh a little (compared to the same cast iron). For their fastening, especially powerful brackets are not needed - even drywall is able to withstand such a small weight. If the pipes are plastic, for installation you only need a set of keys and fittings. But still, bimetallic batteries are easier to install - after all, steel pipes cannot undergo deformation, unlike aluminum, soft metal.
Aluminum + | Bimetallic +
What is cheaper, what is more expensive
The price of bimetallic radiators is one fifth, or even one third, higher than that of aluminum appliances. This is a significant enough difference. It is for this reason that bimetal products are not so widespread in our apartments - they are not accessible to everyone. Bimetallic devices have a higher hydraulic resistance than aluminum. Therefore, more energy is needed to pump hot water. That is, the higher the cost of operation.
And one more thing: about four fifths of all radiators of this type are brought to us from China.This, of course, does not mean that each of them is necessarily bad, but it sometimes makes you think.
Aluminum + | Bimetallic -
Which radiators for which systems are more suitable
1. Now, having examined and compared the main characteristics of radiators, conclusions can be drawn. First, find out which radiators are better - aluminum or bimetal - for an apartment in a multi-storey building. It uses central heating.
And this means that:
- The pressure in the system can change dramatically, reaching extreme values. Water hammering possible.
- The temperature will also not be stable, sometimes changing greatly during the heating season and even a day.
- The composition of the coolant is not clean. It has chemical impurities, as well as abrasive particles. It is hardly possible to speak of a pH not exceeding 8 units.
Based on all this, you can forget about aluminum batteries. Because their central heating system will destroy them. If electrochemical corrosion does not eat, then the pressure with temperature will be finished. And the hydroblow will make the last, "control shot." Therefore, choosing from two types of radiators (aluminum or bimetal), stop only at the last.
2. Now consider the heating system installed in a private house. A well-functioning boiler produces a constant small pressure, not exceeding 1.4 - 10 atmospheres, depending on the boiler and the system. Pressure surges, and especially water hammering, are not observed. The water temperature is also stable, and its purity is not in doubt. There will be no chemical impurities in it, and the pH can always be measured.
Therefore, in such an autonomous heating system, aluminum batteries can also be supplied - these devices will work perfectly. They will cost inexpensively, they have excellent heat dissipation, their design is attractive. In stores, you can pick up batteries made in Europe. It is preferable to choose models made by casting. Bimetal batteries are also suitable for those who live in the house itself. If there is a desire and enough funds, then you can put them.
Just remember that there are a lot of fakes on the market. And if the model (it doesn’t matter, aluminum or bimetal) has a suspiciously low price, then you can already beware. In order not to get into trouble, make sure that on each section and on the packaging (high-quality and full-color) there is a manufacturer's mark.
Video: Installation of aluminum and bimetal heating radiators
