What Is Radiator Heating — And How Does It Work?

Even though 99 percent of 2020’s new single-family homes were built with an air or ground source heat pump or a forced air furnace, older homes and apartment buildings still use a radiator system for heating.

Radiator heating was most popular from the late 1800s to the 1930s. Prior to the introduction of the cast iron radiator, burning wood was the primary source of heat in a home. Once radiators were introduced, they provided a safer and more efficient way to heat homes. 

With heat created from steam rather than an open fire, the radiator has the obvious advantage of being safer, and it also takes less work to provide a steady temperature.

Radiators typically use steam to produce heat. Here’s how a steam radiator works:

• Water is heated in a boiler that is located in a different area than the radiator, typically a basement or utility room. 
• The steam created by the boiling water then travels through pipes to reach the radiator.
• The heat created by the steam heats the radiator itself and that heat is radiated into the room.
• As the steam moves through the coils, it cools and condenses into water, which is then returned to the boiler to begin the process over again.

Another common type of radiator heater uses mineral oil and electricity to produce heat. Here’s how an electric radiator works:

• A heating element located in the bottom of the radiator heats up the mineral oil.
• Because mineral oil, also known as thermal oil or heat transfer oil, has an incredibly high boiling point, it can be heated to very high heats without evaporating.
• The heat from the mineral oil spreads through the body of the radiator and, using convection, heats the surrounding area.

The boiler for a steam-powered radiator can be powered with either electricity or natural gas. An electric radiator uses electricity to power the heating element. 

Because many old buildings and homes still use radiator heating, it’s important to understand the pros and cons of this type of heat.

• While the radiator can be hot to the touch, they don’t get hot enough to be a fire hazard, so they are a very safe form of heating. You can even use them to dry your clothes or pre-heat a blanket before snuggling on the couch. (But cloth, especially polyester, shouldn’t be left on the heater unattended.)
• Electric radiators can be moved to the space where they are most needed.
• Radiator covers give you the opportunity to further customize your home to your style. You may even be able to find one for free and spruce it up a bit!
• They offer a nostalgic feel.
• When they are working properly, they are typically quieter than a furnace that blows air through a home.

• They are hot to the touch, so if there are kids around, it’s important to make sure that little hands don’t get too close.
• They may get loud as they age, and some make banging, whistling, or squeaking sounds if something goes wrong.
• Because of their size, they can make a small space seem smaller.
• Some steam radiators in apartment buildings are set to full blast in the winter, leading to a stuffy — tropical? — feel.