How to Change From Gravity to Main Heating

Gravity furnaces were used from the late 1800s to the early 1900s. It is rare to find one still in use because of their age. These furnaces were designed to burn coal or wood, but many were later retrofired to run on natural gas or oil. Gravity furnaces used the natural process of hot air rising and cold air sinking to move the heat around the house. The pipes that distributed the air around the home typically contained an asbestos covering to insulate them. Removing the asbestos needs to be done by a specialized environmental company to protect your family's health.

Fridge cart
Hand circular saw
Pry bar
Duct work
Registers
Forced air furnace
Venting material

Instructions

- 1
  Remove the gravity furnace from the basement by disconnecting it from the chimney and air pipes. If the furnace is too large to remove in one piece, disassemble it into smaller pieces to be taken out one at a time. A fridge cart helps to move the larger sections from the basement.
- 2
  Remove the air pipes from the inside of the wall systems. This is done by following their path and cutting open the plaster walls with a hand circular saw. Remove the wood laths by prying them off the wall with a pry bar. If any of the furnace's components have asbestos wrapping, contact an environmental company for their removal.
- 3
  Determine paths for the supply and return ducts to run through the wall system. This typically uses interior walls to house the duct work. The walls you cut to remove the old pipes can most likely be used for either the supply or return duct system.
- 4
  Install the supply and return ducts and run them to the location in the basement you have chosen for the forced air furnace. Hiring a qualified HVAC company to determine the ducting requirements and install them is wise, because it requires some knowledge to calculate the proper airflow through the building.
- 5
  Connect the supply and return ducts to the forced air furnace. Vent the furnace's exhaust products out the side of the building to a location that is at least 3 feet from any windows, hot water heater exhaust vents and air conditioner condensers.
- 6
  Connect the thermostat and power supply to the furnace. Have a gas fitter attach a natural gas line to the furnace.
- 7
  Contact your local building authority to inspect your installation before using the new furnace.

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