A gas furnace may be installed in the garage with the following cautions:
- The furnace must have “sealed combustion”, meaning no open flame. The modern condensing gas furnace meets this requirement.
- The burner must be 18 inches above the floor.
- Combustible air should be piped directly to the furnace, garage air should not be used.
- A barrier or curb must be installed to prevent a car from striking the furnace.
- The furnace cannot heat the garage and the space above it, one or the other. Air from the garage cannot be shared with the space above it.
- Ducts must be fireproof or enclosed in fire code sheet rock.
- The condensing gas furnace itself should be enclosed in an insulated room to prevent condensate from freezing.