An HVAC log book records the complete service history of heating and cooling equipment, documenting every maintenance visit, repair, and performance observation over the equipment’s lifespan. This running record tracks patterns, verifies warranty compliance, and guides maintenance decisions. Log books typically span 10-20 years, the typical lifespan of most HVAC systems.
Log Book Contents
Entries include service dates, technician names, specific work performed, system measurements (refrigerant pressures, airflow, temperature differentials), parts replaced, recommended upcoming service, and cost. Modern log books reference serial numbers and equipment specifications. Digital versions can include photographs and PDF service reports attached to date entries.
Maintenance Planning Value
Log books reveal maintenance trends, such as recurring capacitor failures or gradual refrigerant leaks indicating seal degradation. Property managers use logs to schedule preventive service before peak seasons. When equipment fails, log history helps technicians understand prior issues and repair attempts. Log books significantly increase resale value by demonstrating consistent professional maintenance, often justifying 5-10% higher prices for commercial properties.