The systems that fail in January were usually lost in October. A disciplined changeover visit is the cheapest reliability money buys.
Coils, filters and the air path
Wash condenser coils before heating season locks the roof away, replace filters against the pressure-drop log rather than the calendar, and check that dampers actually reach the positions their actuators report.
Water side: glycol, air and strainers
Verify glycol concentration against the design freeze point, bleed air at the high points, and clean strainers while flow is easy to isolate. A partially blocked strainer hides all summer and starves a coil on the first cold morning.
Prove the heating sources early
Run every heat pump, burner and electric stage to temperature in autumn — on a mild day when a failure is an inconvenience, not an emergency. Log defrost behaviour on the first cold snap and compare against last year.
Close the loop in the log
Record what was measured, not just what was done. Trend lines across seasons name the coil that fouls fast and the belt that keeps stretching — evidence that turns next year’s visit from a tour into a repair list.
