What must be present in addition to unvented space heaters for them to be used safely?

For unvented space heaters, the presence of an oxygen depletion safety system is essential for safe operation. This system is designed to monitor the levels of oxygen in the room. Unvented heaters consume oxygen from the space in which they operate, and if the oxygen levels drop too low, it can create dangerous conditions, including the risk of suffocation. The oxygen depletion safety system actively detects such conditions and automatically turns off the heater to prevent harm.

While thermostatic controls can enhance comfort by automatically regulating temperature, they do not address the safety concerns related to oxygen consumption. Protective coverings may provide physical safety but do not affect the operation of the heater itself. Carbon filter systems might assist in reducing emissions or odors but are not specifically required for the safe operation of unvented space heaters. Thus, without the oxygen depletion safety system, using unvented heaters can pose significant health risks.