Self-Test A-3.3 Gas Appliance Draft

Complete Self-Test A-3.3 and check your answers.

1. What is a natural draft in a vent created by?
   1. The height and diameter of the vent.
   2. Atmospheric pressure and the height of the vent.
   3. The outdoor design temperature and diameter of the vent.
   4. The difference in densities of vent gases and ambient room air.

    

2. What is a down draft?
   1. A draft produced by a mechanical device downstream from the combustion zone.
   2. A draft produced by a mechanical device upstream from the combustion zone.
   3. A draft produced by the upward movement of hot gases, creating a negative pressure.
   4. A condition in which a draft is forced downward and can cause flue-gas spillage.

    

3. There is no limit to the benefits gained by increasing the vent height.
   1. True
   2. False

    

4. Other than admitting dilution air, what is the other function of a draft hood?
   1. Allows for spillage
   2. Keeps the vent cold
   3. Neutralizes excess air
   4. Prevents back drafts in the common vent

    

5. What is the maximum efficiency of a Category I appliance?
   1. 17%
   2. 70%
   3. 83%
   4. 90%

    

6. What is an induced draft?
   1. A draft produced by a mechanical device downstream from the combustion zone.
   2. A draft produced by a mechanical device upstream from the combustion zone.
   3. A draft produced by the upward movement of hot gases, creating a negative pressure.
   4. A condition in which a draft is forced downward, possibly causing flue-gas spillage.

    

Answer Key: Self-Test A-3.3 is on the next page.