1.   Another common source of indoor pollution is improperly maintained or improperly used heating units.

2.   Another danger sign would be the inability to shut off gas to an appliance or heating unit.

3.   A fan pulls in air and circulates it past a heating unit, either electric or gas, into a rotating drum holding the clothes.

4.   Even though the inserts are efficient as heating units, they do detract from the charm of the fireplace.

5.   Even new houses with top-of-the-line heating units can experience malfunctions.

6.   Fish and wildlife will survive in large ponds, but may need an aerating pump or heating unit in small ones.

7.   Heating units are warmed by either oil-filled coils, which can get very hot to the touch, or by an electrical element.

8.   Keep the heating unit moving to avoid overheating any single area.

9.   Officials believe the fire originated in the middle of the historic church, where there are air conditioning and heating units, a kitchen and storage facilities.

10.   Place it in a spot away from stoves and other heating units as well as drafts.