How to Cure a Furnace

A cracked furnace loses heat and is potentially dangerous if fuel or smoke is leaking out. They is expensive to replace. However, you can repair it yourself with high-temperature stove and furnace cement. This cement works on old and new furnaces, regardless of the type of fuel they use. It withstands temperatures up to 1400 degrees F. It is critical that furnace cement is properly cured to make sure the seal lasts.

High-temp stove and furnace cement
Liquid dish soap
Cloth
Stir stick
Trowel

Instructions

- 1
  Allow the furnace to cool completely.
- 2
  Clean the cracked area with soapy water to remove grease and residue. Rinse thoroughly, but do not dry.
- 3
  Stir the cement in it's container with a stir stick. Add a few drops of water, if necessary, to make it easier to stir and spread.
- 4
  Apply a light coat of cement over the wet crack, working it into the crack with a spatula, small putty knife or trowel. Follow with a second, heavier coat and smooth the edges. Allow to dry for anywhere from one to 24 hours, according to the package directions.
- 5
  Set the furnace to the lowest possible setting and allow it to heat up to the designated setting.
- 6
  Increase the amount of heat in small increments, allowing the furnace to reach each new temperature before increasing the temperature again. Use the increments available on your furnace, or follow the package instructions.
- 7
  Continue gradually increasing the temperature until the furnace is on full blast. The heat from the furnace is what cures the cement. Curing times vary from 30 to 120 minutes, depending on the particular product you use.

How to Set the Weight for an HVAC Furnace

How to Adjust Water Pressure on a Peerless Boiler

Heating & Cooling Repair