Gas Fitter Practice Test

Which factor can contribute to positive air pressure in a home?

1. Excessive use of exhaust fans

2. Open windows

3. Centrally located heating units

4. Sealed duct systems

The correct answer is: Excessive use of exhaust fans

The correct answer relates to the circumstances under which positive air pressure can develop within a home. Centralized heating units can play a significant role in creating positive air pressure when they are located centrally within the home. These systems can heat air and circulate it throughout the house, which can result in an overall increase in air pressure, especially if windows and doors are closed. When centrally located heating systems operate, they can force warm air into the living spaces, which can lead to a buildup of pressure if the air cannot easily escape through ventilation paths. As this air expands and is heated, it can create positive pressure, particularly if there are no significant air leaks or other factors that would allow for the easy escape of air. In contrast, excessive use of exhaust fans could contribute to negative air pressure, as these fans ventilate air out of the home. Open windows would allow outside air to enter and can also be a way to equalize pressure but are not typically a direct cause of positive air pressure. Sealed duct systems alone do not inherently create positive pressure; they improve airflow efficiency but do not prevent the loss of air that could maintain or create a positive pressure condition. Therefore, centrally located heating units are influential in generating positive air pressure in a home setting