Type III — low-pressure appliancesDifficulty 4/5
Why must water be circulated through or removed from a chiller while its refrigerant is being evacuated?
- AWater circulation is required to keep the purge unit operating during the evacuation
- BBoiling refrigerant absorbs heat and standing water in the tubes will freeze and split them
- CCirculating water raises the system pressure and shortens the time recovery takes
- DMoving water prevents sediment settling and blocking the evaporator tube bundle
Show answer and rationale
Correct: B. Evaporating refrigerant draws its latent heat from whatever is nearest, which is the water in the tubes. Ice expands, and a split tube bundle is an expensive and entirely avoidable failure.
- C — Circulation does not meaningfully raise system pressure or accelerate the recovery.
- D — Sediment is a maintenance concern generally, not the reason for circulating during evacuation.
- A — Purge units operate independently of whether the chiller water is moving.