What is the purpose of interlocks in HVAC control systems?

• A. To prevent dangerous or unsafe operation by ensuring proper sequencing.
• B. To increase energy use.
• C. To adjust color of lights.
• D. To simplify maintenance.

Answer: (A)

Interlocks are safety devices that require certain conditions to be true before equipment can start or continue operating. The main purpose is to prevent dangerous or unsafe operation by ensuring proper sequencing of components. For example, a burner should not ignite unless the venting and air conditions are verified, and dampers or valves must be in correct positions before fans or compressors run. If a condition isn’t met, the interlock blocks operation and can trigger a fault or lockout to alert maintenance. This protects occupants and equipment from hazards and helps ensure the system starts, runs, and shuts down in a safe, orderly way. The other options don’t fit because interlocks aren’t about increasing energy use, changing light colors, or primarily simplifying maintenance.