Rock the Gas Heat ESCO Exam 2025 – Fire Up Your Future in HVAC!

The elbow for the combustion air intake in a Category IV two-pipe vent system should point up above the roof. This positioning is essential for several reasons. By pointing upwards, it helps ensure that the combustion air intake is not directly exposed to any potential contaminants or debris that could fall toward it, which could obstruct the airflow or affect combustion efficiency.

Additionally, directing the elbow upwards allows for effective drainage of any condensation that might occur within the vent system, preventing water from pooling and potentially causing functional issues later. This orientation also helps minimize the risk of water entering the venting system, maintaining proper operation and efficiency in the heating system.

In contrast, pointing the elbow down could allow rain or snow to enter the system, while having a rain cap or angling it might not provide the same level of protection or effective airflow as a direct upward point would ensure. Thus, the upward direction is the most suitable and functional design choice for the combustion air intake in this context.