A.O. Smith 500 User's Information Manual page 2

THE UNIT SHOULD NOT BE INSTALLED DIRECTLY ON A
CARPETED FLOOR. A FIRE HAZARD MAY RESULT. Instead,
the boiler must be installed on the A. O. Smith Combustible
Floor Kit Base or concrete blocks extending beyond the full width
and depth of the boiler by at least 3 (76.2mm) inches. If the
boiler is installed in a carpeted alcove, the entire floor must be
covered with concrete blocks, or use the A. O. Smith Combustible
Floor Kit Base.
Lighting Instructions for the G(B/W) 300 through 750 models
FLAMMABLE ITEMS, PRESSURIZED CONTAINERS OR ANY
OTHER POTENTIAL FIRE HAZARDOUS ARTICLES MUST
NEVER BE PLACED ON OR ADJACENT TO THE BOILER. OPEN
CONTAINERS OF FLAMMABLE MATERIAL SHOULD NOT BE
STORED OR USED IN THE SAME ROOM WITH THE BOILER.
Light the unit in accordance with the instructions on the lighting
and operating label attached to the boiler. These instructions
are repeated on the following two pages.
2