How to Retrofit an Octopus Furnace

Octopus furnaces were popular in the early 1900s.

Gravity furnaces, sometimes called “octopus furnaces,” are an old type of gas-burning heater. These furnaces were used during the 1800s and 1900s. They’re referred to as octopus furnaces due to the several ducts that connect to the main heating unit. When an appliance is retrofitted, an element is added to it that it didn’t originally have. This way, an old appliance, like a gravity furnace, can be modernized and used in a contemporary household or building. When retrofitting any heating system, it’s not a case of one-size-fits-all; there are several options that need to be considered.

Things You'll Need

• Heat source
• Ducts
• Insulation

Instructions

1. Choose the heat source that will be used in the future; this depends on location and cost. Depending on the geographical area, options for gravity furnaces may include coal, oil, natural gas or wood. If the gravity furnace has been running on coal, it’s not necessary to continue using this fuel source if there are other less expensive sources available.

2. Ask a contractor to look at the heating system, to check that all of the seals and joints on the system are intact. A contractor should also be able to determine if heat is escaping in any areas of the home; fixing these trouble spots will cut down on the heating bill.

3. Replace any ducts that are letting heat escape.

4. Replace asbestos insulation with modern insulation. The ducts and pipes of the gravity furnace should be insulated.

Tips & Warnings

• There is no fan to replace on an octopus furnace. Fuel is burned in the main area of the furnace, and the heat goes through the ducts to different areas of the house.

• Gravity furnaces use up an extremely high amount of heat, raising utility costs much more than necessary. Since older appliances tend to be much larger than necessary, it may not be an option to have it quickly removed from the home. However, due to their high costs, it’s often best to simply utilize a newer heating system in the home, than try to upgrade a gravity furnace. There aren’t many changes that can be made to an octopus furnace, and practically nothing can be done about its efficiency rate.

• Hire a licensed professional to remove any parts and materials in the furnace that contain asbestos. Asbestos was commonly used at the time that gravity furnaces were popular, but today it’s widely known that asbestos is bad for health. There is most likely asbestos wrapped around the pipes and ducts to provide insulation.

References

• Energy Savers: Furnaces and Boilers
• Home Tips: Do You Have a Gravity Furnace
• Accurate Inspections: Gravity Furnace System