Technical Standards and Safety Authority (TSSA) G3 Practice Exam

Which type of appliance is a category I Appliance?

1. an appliance with a power burner

2. a natural gas or propane-fired water heater or central furnace

3. an appliance that operates with a non-positive vent static pressure and a flue loss of not less than 17%

4. an appliance that operates with a positive vent static pressure and a flue loss of not less than 17%

The correct answer is: an appliance that operates with a non-positive vent static pressure and a flue loss of not less than 17%

A category I appliance is characterized by its operation with a non-positive vent static pressure, meaning that these appliances vent their combustion gases by relying on natural draft or negative pressure rather than forced ventilation. This is significant because it impacts how these appliances are designed, installed, and maintained in terms of safety and efficiency. Choosing this type of appliance typically refers to how combustion gases are expelled and the resultant pressure conditions during operation. Category I appliances usually include those that operate with flue losses that might reach a certain threshold, which indicates their effectiveness and the proper functioning of the venting systems. In contrast, appliances with power burners and those firing natural gas or propane may not fit the criteria of a category I appliance because they can feature different venting methods and pressure conditions. The terminology around positive vent static pressure and particular flue loss percentages directly pertains to other categories of appliances or different design parameters altogether.