The Basics of Cast Iron Radiators

While not as common in modern homes, the cast iron radiators are still a very efficient way to heat and is used often in office buildings and apartment complexes. Basically, very hot water or low-pressure steam is forced through pipes into the radiator unit. The hot medium then heats the metal and the process of convection warms the air around it. Find out more here.

The hot water type radiator is a sealed system, which delivers the liquid through a gravity feed, pressure pump or just convection. As the water cools, it sinks and is forced through a lower pipe opposite the intake line for return to the heating unit.

Cast iron steam radiators were the first type used as the heated steam uses its own pressure rather than an electric pump to force it through the pipes to the individual room radiator units. While it is better at distributing the hot steam through large or tall buildings, the higher temperature required is less energy efficient as heat loss across the system is more prevalent.

Both of these types of radiator systems are prone to a loud banging sound as the liquid or steam moves through the system. A surge or drop in pressure in different parts of the system causes this. In a steam system, the faster, higher-pressure steam crossing its surface will pick up water condensed in a horizontal section and the resultant water “slug” is flung along the line. This can wear out joints and, if the pressure is high enough, can cause a pipeline burst.

In closed steam systems, there are two cast iron radiator valves, one at the highest location and a second at the lowest. Opening both valves and draining the system before closing and restarting will fix the problem until it builds up again.

Modern portable electric radiators are usually filled with a liquid such as oil. The oil is then pushed through the pipes for convection release into the air space around the heater.

Some older cast iron radiators have an antique look to them. When redesigning an old home or apartment people often leave the Victorian cast iron radiators there for the look as well as the heat. If you are trying to find antique looking radiators that are no longer produced one way you may be able to find something interesting is by looking at used cast iron radiators. Make sure any radiator you buy is in good working order.