December 2 - December 4 Duct and Envelope Tightness (DET) Verifier – Online Training Online This three-day online course is designed to introduce the skills necessary to become a Duct and Envelope Tightness (DET) Verifier, certified to perform the diagnostic testing required for new homes … Continue reading "Duct and Envelope Tightness (DET) Verifier – Online Training"