What is a characteristic of Class IV devices compared to Class I devices?

Class IV devices are designed with specific characteristics to improve performance and safety in a building environment. One of the defining features of these devices is that they are engineered to operate efficiently without causing backdrafting or spillage. This is crucial, especially in situations where maintaining proper airflow and combustion safety is essential, such as in homes with fuel-burning appliances.

The absence of backdrafting and spillage ensures that harmful gases, such as carbon monoxide, are not inadvertently drawn back into the living space, thereby protecting the health and safety of the occupants. This characteristic is contrasted with Class I devices, which may not have the same level of precaution built into their design.

In terms of energy consumption, cost, and installation complexity, Class IV devices may indeed differ from Class I devices, but it is the design features that mitigate risks like backdrafting and spillage that are most significant in distinguishing them. Thus, this makes the lack of backdrafting and spillage a key characteristic of Class IV devices.