When flushing the system, you should flush until what condition is met?

• A. Water is clear
• B. Pressure is restored
• C. Air is expelled
• D. Temperature is uniform

Answer: (A)

When flushing a system, you’re trying to purge air and any debris from the line so the flow is clean and uninterrupted. The clearest sign that this purge is complete is when the water comes out clear, showing that particulates and entrained air have been flushed out. If the water is still cloudy or has visible bubbles, the system isn’t fully purged yet and you should continue flushing.

Relying on pressure restoration isn’t a reliable flush indicator on its own, since pressure can return for reasons unrelated to how clean the line is. Air being expelled happens during flushing, but that alone doesn’t guarantee everything is cleared. Temperature uniformity isn’t a criterion for completing a flush. So the correct condition to look for is clear water.