G2 Gas Fitter Practice Exam

What describes a category 2 appliance?

1. An appliance that operates with a positive vent static pressure

2. An appliance that operates with a negative vent static pressure

3. An appliance that operates with a positive vent static pressure and a flue loss of less than 17%

4. An appliance that operates with a flue loss of not less than 17%

The correct answer is: An appliance that operates with a negative vent static pressure

A category 2 appliance is characterized specifically by its operation with a negative vent static pressure. This type of appliance is designed to vent products of combustion safely, ensuring that there is a proper flow of combustion gases without back pressure affecting the appliance's performance. A negative static pressure indicates that the appliance is drawing air into the combustion chamber, which is crucial for its efficiency and safety, as it helps prevent the escape of combustion gases into the living space. In contrast, the other options refer to different conditions or types of appliances. Operating with a positive vent static pressure is not typical for category 2 appliances, as this may lead to improper venting and potential safety hazards. Additionally, while flue loss percentages are relevant when classifying appliances, the defining characteristic of category 2 is its operational pressure rather than specific loss metrics. Thus, the emphasis on negative vent static pressure highlights the operational mechanics critical for ensuring the effectiveness and safety of these types of appliances.