Switching compressors between cycles of every how many minutes is best?

• A. 2
• B. 3
• C. 1
• D. 4

Answer: (A)

The principle being tested is equal duty cycling of multiple compressors to balance wear and heat and maintain stable performance. Switching between compressors every two minutes keeps the workload shared evenly, so no single unit bears most of the run time. This equalizes heat generation and wear across units, helping extend overall system life and avoid overheating or uneven performance.

Choosing a much shorter interval, like every minute, would increase the number of startups and shutdowns, which can wear components faster and shorten life. Waiting longer, such as every three or four minutes, risks one compressor staying on longer than the other, leading to uneven wear and potential overheating. Two minutes is a practical compromise that promotes even duty cycling while avoiding excessive startup stress.