Which statement best contrasts electric defrost and hot-gas defrost in terms of heat source and typical use?

• A. Electric defrost uses water heating; hot-gas defrost uses steam.
• B. Electric defrost uses electric heating elements; hot-gas defrost uses hot refrigerant gas; electric defrost is slower and can use more energy; hot-gas defrost is faster but more complex.
• C. Electric defrost uses electric heating elements; hot-gas defrost uses cold refrigerant gas.
• D. Electric defrost is faster and more efficient than hot-gas defrost.

Answer: (B)

Electric defrost relies on electric heating elements to melt frost on the evaporator. During the defrost cycle, electricity heats those elements, transferring heat to the coils. This approach is common in smaller or simpler cooling systems, but the heating is gradual and, if the cycle runs longer to clear frost, it can use more energy overall.

Hot-gas defrost sends hot refrigerant gas from the compressor path through the evaporator to melt frost. Because the heat source is the hot gas already in the refrigeration cycle, defrosting is usually much faster. The trade-off is added mechanical complexity, with extra valves and piping, so it’s typically used on commercial equipment where speed and reliability are important.

So the best description is that electric defrost uses electric heating elements, hot-gas defrost uses hot refrigerant gas, electric defrost is slower and can use more energy, and hot-gas defrost is faster but more complex.