Floor-mounted-type unit heaters shall comply with the following requirements:
1. A listed unit heater shall be installed with clearances from combustible material at the back and one side only of not less than 6 inches (150 mm). Where the flue gases are vented horizontally, the 6 inches (150 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 instructions.
2. Floor-mounted-type unit heaters installed on combustible floors shall be listed for such installation.
3. Combustible floors under unlisted floor- mounted unit heaters shall be protected in an approved manner.
4. Clearances for servicing shall be in accordance with the manufacturer's recommendations contained in the installation instructions.