Floor-mounted-type unit heaters shall comply with the following requirements:
- A listed unit heater shall be installed with clearances from combustible material at the back and one side of not less than 6 inches (152 mm). Where the flue gases are vented horizontally, the 6 inch (152 mm) clearance shall be measured from the draft hood or vent instead of the rear wall of the unit heater. A unit heater listed for reduced clearances shall be installed in accordance with its listing and the manufacturer's installation instructions.
- Floor-mounted-type unit heaters installed on combustible floors shall be listed for such installation.
- Combustible floors under unlisted floor-mounted unit heaters shall be protected in an approved manner.
- Clearances for servicing shall be in accordance with the manufacturer's instructions.