Defrost Energy Calculator

Calculate daily and annual energy consumption, cost, and recovery time for defrost systems.

Electric: heater elements. Hot gas: uses discharge gas. Off-cycle: fan only, no added heat.
Total wattage of defrost heaters. Check nameplate. Typical: 1-6 kW per evaporator.
kW
Number of defrost cycles per 24 hours. Typical: 2-6 for coolers, 4-8 for freezers.
per day
Length of each defrost cycle. Typical: 15-45 minutes for electric, 5-15 for hot gas.
minutes
Drain pan and line heaters that run during defrost. Set to 0 if none.
kW
Cost per kilowatt-hour from your electric bill.
$/kWh

Results

Daily Defrost Energy:
Total electrical energy consumed by defrost heaters per day.
-kWh/day
Annual Defrost Energy:
Total annual energy consumed by defrost system.
-kWh/yr
Annual Defrost Cost:
Annual electricity cost for defrost operation only.
-$/yr
Daily Defrost Time:
Total time the system is in defrost mode per day. Reduces cooling time available.
-hrs/day
Est. Recovery Time:
Estimated time to pull box temperature back to setpoint after each defrost cycle.
-min/defrost
Reference: ASHRAE Refrigeration Handbook Ch. 14. Heatcraft, Larkin defrost engineering data.