Central heating systems are affected by corrosion and pressure fluctuations. The most efficient radiators to withstand these conditions are made from cast iron and metal.
Comparison of characteristics of cast iron and bimetallic batteries
Cast iron heaters are classic models. They have been in use for many decades.
Bimetallic radiators appeared on the market not so long ago. They are distinguished by a high level of efficiency and good technical characteristics.
When choosing, an important role is played by the duration of service and the price category of the product. Knowledge of the features of each type helps to compare designs and make a choice in favor of the best option.
Design and appearance
Modern cast iron batteries have a new design. There are radiators from foreign manufacturers on the market. The surface of the products is covered with molded patterns. Such models are suitable for modern renovations.
Cast iron batteries are made up of monolithic sections with rubber gaskets between them for tightness. The radiator can be modified by removing an extra section or adding a new one. The length of the device depends on the number of sections. The height is 0.35-1.5 m, and the depth is 0.5 m.
Cast iron is characterized by gradual heating, so a large amount of hot water is required. This explains the width of the channels of the structure. Unlike other types, each section of a cast iron radiator includes two parallel compartments, which provides high heat transfer.
In some heating devices, feathers are installed between the channels. They provide a high level of convection heating. The efficiency level of such batteries is 5-10% higher than that of the base model.
The base of the bimetallic models is made of aluminum. The radiators are ribbed for optimal heat dissipation. A robust steel core is located under the body. The alloy provides the device with a high level of reliability. Bimetallic structures include sections. There are also monolithic structures. The design of bimetallic products is attractive.
Heat dissipation
To choose cast iron or bimetal for central heating, you need to take into account their ability to give off heat. The heat transfer of cast iron devices is characterized by a high level of inertia. Cast iron takes a long time to warm up, so the room does not become warm immediately. Cooling down of a heated radiator takes a long time, which is a plus in case of accidents.
The functionality of cast iron models is based on convection and infrared radiation. The air and objects in the room are warming up. The average heat transfer rate is 100-160 W, but deviations are noted in some radiators.
Bimetallic models are characterized by a low degree of inertia. This ensures rapid warming up of the room. When the heat supply is cut off, the radiator cools down just as quickly. The heat transfer index of the section of the device is 150-180 W.It is close to the markers of cast iron products, so it is difficult to clearly determine which radiators are better, cast iron or bimetallic.
Ability to hold pressure
The pressure in houses with a large number of floors is not stable. The circulation pumps must be operated smoothly, but the condition is not always met. When hot water stops flowing, the pressure in the system rises to such high levels that the batteries begin to burst. It is recommended to opt for a model with good pressure performance.
Cast iron radiators withstand 9-12 atmospheres. This is a low indicator for water hammer. Bimetallic models can withstand up to 20-50 atmospheres. Powerful hydraulic shocks do not violate the structural integrity of this type of radiator. Models with a monolithic steel core can withstand up to 100 atmospheres.
It is recommended to change cast-iron batteries to modern ones in multi-storey buildings.
Maximum coolant temperature
The coolant temperature is unstable. Cast iron batteries can heat up to 110 degrees. Hot water passing through bimetallic models is heated up to 130 degrees. Both types tolerate swings.
Due to the difference in expansion between steel and aluminum, bimetallic batteries sometimes crack when the temperature changes.
Durability
Cast iron products last up to 50 years. Some older houses have preserved models that are over 100 years old. The warranty period for bimetallic structures is 15-30 years.
Dismantling of old and installation of new radiators
Replacement of batteries is carried out after the end of the heating season. In the same period, preventive measures are taken. When batteries are removed, utilities must be notified to prevent water from entering the system or draining water from the circuits. The tightness of the connection is ensured by two nuts. One is used to connect the pipe to the battery, and the other is a locknut.
When dismantling, the following sequence should be followed:
- A nut with a small diameter is unscrewed for the entire length of the squeegee thread.
- The nut connecting the pipe to the battery is unscrewed.
- The radiator is removed.
Cast iron batteries are very heavy. Sometimes they have to be cut into several pieces. Despite the fact that the water is drained from the riser, it may remain in the radiator. Prepare a rag and a bucket in advance. Otherwise, the flooring could be damaged.
The main problem when dismantling cast iron products is that the nut may not loosen. In this case, you need to warm up the connection with a blowtorch. The second way is to use a grinder.
Before starting the installation of cast iron products, you should decide on the installation site. An area with maximum heat loss is selected. Typically, batteries are installed near windows or front doors. In the kitchen, they are placed under the windowsill.
During installation, you should:
- clearly define the middle of the window opening and mark on both sides the points for the installation of fasteners;
- position the radiator at a height of 8-14 cm from the floor;
- maintain a distance between the window sill and the heating device of 10-12 cm;
- leave a gap between the radiator and the wall at least 3 cm.
Installation depends on the wall material. They must be flat and clean. If the attachment is made to a wooden surface, a special stand is constructed. The brick surface suggests mounting brackets in a niche. A solid support is being prepared for a drywall wall.
Dismantling of bimetallic structures involves draining water from the heating system and unscrewing the device from the pipe. To change the battery, they often resort to blocking the pipe suitable for the radiator.Each battery has a special valve that allows you to drain the water. The radiator is unscrewed with a gas wrench.
Before installation, bimetallic models are cleaned with alkali-free detergents. The screw connections are not stripped. When installing, a multi-start thread is used. Threaded elements are mounted with a force not exceeding 12 kg.
Installation assumes the following sequence:
- Places for brackets are marked. This takes into account the location of the pipes and the design features of the radiator.
- A level is used that excludes skews.
- The indicators of the minimum distance of radiators from walls and floors are taken into account.
- The battery is hung on the brackets.
- The device is connected to pipes.
- An air release valve is installed.
Bimetallic radiators are quite lightweight, as they mainly consist of aluminum. With knowledge of the installation rules, they can also be strengthened on a plasterboard partition.
Recommendations for choosing batteries for heating
The choice of cast iron or bimetallic radiators depends on the type of building and interior. In old low-rise buildings, Khrushchevs, it is recommended to install cast iron products. In the absence of the effect of powerful water hammers, the system pressure of the device is maintained.
If the apartment is in a building with a large number of floors, the working pressure marker in the coolant will be higher. It is recommended to resort to the installation of bimetallic structures with a high resource. Cast iron batteries should be replaced with bimetallic ones if there is an autonomous heating system.
