A common hazard associated with central heating appliances, unit heaters, and room heaters is:

• A. the thermostat temperature limit controls
• B. proximity of installation to combustibles
• C. static electricity
• D. the explosion potential

Answer: (B)

The key safety issue is keeping heat-producing devices away from materials that could ignite. When central heating appliances, unit heaters, or room heaters are installed near combustibles like curtains, furniture, paper, or wood, the nearby heat or hot surfaces can start a fire even under normal operation. That's why codes specify minimum clearances and, if needed, shields or noncombustible barriers. The thermostat’s temperature limit controls are safety features that help prevent overheating, but they aren’t the hazard themselves. Static electricity isn’t a typical fire risk from these heaters in ordinary use, and explosions are not a common risk unless a separate fault creates a flammable-air condition. So proximity to combustibles is the most common hazard.