For two-zone testing, the defrost free operation enables continuous testing without requiring any defrosting for up to 500 hours. The 500 hours eliminates 20 defrost cycles in that period of time. ESPEC has developed a unique patent structure that prevents the penetration of outside air and uses recirculated air during testing to stop frosting when at low temperatures.

The defrost-free operation can reduce both the test time ( 60 minutes each cycle) and the power usage for the defrosting process (13.6 kWh each time).