Why are high point vents opened during filling?

Why are high point vents opened during filling?

• A. To allow air to vent.
• B. To introduce air into the system.
• C. To vent water vapor only after fill.
• D. To regulate system pressure.

Answer: (A)

Air pockets tend to collect at the highest points when a system is being filled. Opening high point vents gives those trapped air a path to escape as the incoming water pushes the air upward. This allows the system to fill completely with water, ensures proper circulation, and avoids air-related problems like reduced heat transfer, noise, or pressure surges. So the best reason is to vent air. Introducing air would defeat the purpose, venting water vapor only after filling doesn’t address air during the filling process, and while venting can help with pressure control, the primary function here is removing air to allow proper filling.

Air pockets tend to collect at the highest points when a system is being filled. Opening high point vents gives those trapped air a path to escape as the incoming water pushes the air upward. This allows the system to fill completely with water, ensures proper circulation, and avoids air-related problems like reduced heat transfer, noise, or pressure surges.

So the best reason is to vent air. Introducing air would defeat the purpose, venting water vapor only after filling doesn’t address air during the filling process, and while venting can help with pressure control, the primary function here is removing air to allow proper filling.