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What Is A Gravity Furnace?

By January 18, 2019 Uncategorized No Comments

What Is A Gravity Furnace & How Does It Work?

gravity furnace image

Gravity furnaces were one of the most popular ways to heat homes way back in the day.

Gravity furnaces were quite popular back in the day.

These types of furnaces were installed from the late 1800’s to approximately the mid 1900’s, before gas and electric furnaces became the standard.

If you’ve ever seen one, you know they can look quite intimidating due to their size!

How Do Gravity Furnaces Work?

Gravity furnace operation is quite simple.

A fuel is inserted into the combustion chamber which would then heat the air surrounding it, and then this air would then rise through the duct work to heat the rest of the home.

Heat naturally rises, so there was no blower or motors involved.

The original gravity furnaces ran on coal, which would have to be replaced on a regular basis to keep the heat flowing.

In essence, it was a giant stove that heated the home at the time.

As technology progressed, new fuel sources such as propane, oil, and natural gas replaced the coal to heat the furnace. 

Disadvantages of Gravity Furnaces

Most gravity furnaces today are due to be replaced just based on their age alone. If that’s not convincing enough, here are some other good reasons to replace:

  • Low Efficiency – Today, furnace efficiency starts at 80% and go all the way up to 98%. Meaning at least 80% of the fuel burned is used to heat the home. Gravity furnaces on the other hand are lucky if they get to 50%. That’s a lot of wasted fuel and energy.
  • Slow to heat home – because gravity furnaces don’t have blowers or motors, the time it takes to heat the home is much longer that a standard gas furnace of today.
  • Not compatible with air conditioning – due to the fact that gravity furnaces don’t have blower motors, you wouldn’t be able to have an air conditioner installed as AC’s rely on the furnace blower to blow the cold air through your home.
  • Asbestos – this hazardous material is a popular insulator and fireproofing material used around gravity furnaces. This material was eventually found to be hazardous and even cancer causing if inhaled.
  • Limited repairs – due to the sheer age of these furnaces, having a furnace repair completed on one is almost impossible. Not to mention that it would be a general waste of money as well. Parts for these units are generally not manufactured anymore.