Heat breaks in winter and cool breaks in summer
It’s part one of the natural law of things that break. Part two is that all things break at the same time. Preventive maintenance checks the heat before winter and the cool before summer allowing more time for correction.
Most of what follows refers to BSTs (Big Scary Things) that only exist in commercial buildings like schools and office buildings.
Private homes have LSTs (Little Scary Things) which means there are less things to break and check. Good news right? But read on anyways and be thankful that's not you.
Calibration of fan and filter differential pressure switches (proof switches) reduces alarms and ensures the heat and cool cycles will be available.
Verification of economizer damper operation allows savings balance and fresh air.
The operative term in prevention is pre, which allows you to ‘pre-act’ instead of react. Records of testing and verification dates ensure periodic inspection and evaluation of operating conditions. This is true of BSTs and LSTs.