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What Kind of Radiator Do You Have? How To Tell

Heating, Older Homes


If you have radiators in your home, it can be difficult to tell if you have steam heating or hot water heating. Both heating systems are common in vintage homes, and both provide clean, dust-free heat. How can you tell them apart? Here are a few tips to help you determine which type of radiator heating system you have.      

Whether it’s hot water radiators, steam radiators, or any other type of heating system, American Vintage Home can help you today. Call us now at (847) 999-4595 to get started.

Boiler Steam Heating System

A steam heating system uses a boiler to turn water into steam. The steam then circulates through pipes to radiators and warms the home. As the steam cools, it condenses back into water and returns to the boiler to be heated again. Indicators of steam heating systems:

Number of pipes

  • One pipe: If you see only one pipe coming from your radiator, that means you have a one-pipe system, and it’s definitely steam. The steam comes through the pipe, the heat is dispersed, the steam condenses in the radiator, and the water returns through the same pipe to the boiler.
  • Two pipes: Two pipes coming from the radiator means it could be a hot water or steam system. In a two-pipe steam system, the steam comes into the radiator from one pipe, and the condensing process occurs in the other pipe, returning water to the boiler.

Older style radiator

High-pitched whistle
If you sometimes hear a high-pitched whistle coming from your radiator, you most likely have a steam heating system. The whistling can also be an indicator that your steam heating system needs maintenance. 


Sight glass

You will have to go to the basement and look at the boiler for this part. Steam heating systems should always have a sight glass attached vertically to the outside of the boiler. A sight glass is a transparent glass cylinder that is about 12 inches tall, filled partly with water to indicate the level of liquid contained within the system.

Sight glass radiator

Hot Water Heating

In a water heating system, the hot water travels from the boiler through a circulating pump to the radiator, which diffuses the heat and warms the room. The water continues to circulate through the system when the heat is on. Indicators of hot water heating systems:

Two pipes
Hot water systems will always have two pipes coming from the radiator not necessarily from different corners. However, some steam heating systems also use two pipes, so more investigation is needed

Two pipes radiator


Circulating pump
If a circulating pump is attached to your boiler heating system, it usually means you have a hot water system. Circulating pumps come in all sorts of vibrant colors.

Circulating tank

Expansion tank
If you have hot water heating, you should also have an expansion tank near the boiler. The expansion tank protects the hot water system from building up excessive pressure.

Expansion tank

Both steam and hot water systems should be serviced annually to ensure trouble-free operation. Steam systems particularly require special care that should be performed regularly. Whoever you choose to maintain your heating system, make sure they have a lot of experience and are knowledgeable about the needs of older homes.

We hope this guide helps you learn more about your heating system. No matter what type of heating system you have, we can help maintain it.

Need radiator repair or replacement services in the North Shore area of Chicago? If you would like our expert help, call American Vintage Home at (847) 999-4595 or fill out our online form today.

Additional Radiator Resources

The Ultimate Guide to Radiators

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