Trend Analysis is a powerful tool for HVAC troubleshooting. It can help: solve operating problems; increase energy efficiency; locate defective hardware; identify out-of-calibration devices; improve occupant comfort; and extend equipment life. It would be impossible to anticipate all variables when developing and implementing a sequence of operation for an air handling system. The designer must be able to see the unit in action, and the interaction between the different devices. The designer must also be able to see the unit`s operation over a significant period of time and over a wide range of conditions. HVAC Trend Analysis can do all these things.