If the batteries stopped holding heat and the house is colder every day, then the time has come to change heating radiators. You can choose such radiators that are optimal for you. Aluminum, steel, cast -iron, as well as bimetallic radiators are usually used. Cast iron batteries were mainly used earlier. They can be found in apartments that were built for a very long time. The advantage of such batteries will be their reliability and durability. They are not very expensive, and they can last about 50 years. But they are quite heavy and have high thermal inertia. You will also need a primer concrete contact consumption on it is small.
Steel radiators have greater heat transfer, low thermal inertia, as well as light weight. They are used in apartment buildings, but they will not be so durable. Aluminum batteries are becoming more popular. They weigh little, and they can also be adjusted to any room. But at the same time, pressure and temperature surges may appear. Bimetallic radiators will be the most successful option. They will last a long time, their strength will be very good, and they are also suitable for an open heating system. But such batteries will be the most expensive of all options.