The modern commercial fryer has improved energy efficiency, resulting from better heat transfer systems. Commercial fryers with infrared heating or convection heating are efficient, but often expensive. Infrared heating uses a radiant heat transfer process and convection heating operates through air circulating, while standard fryers utilize hot combustion gases. The most common fryer models are electric and gas fryers.
Electric restaurant fryers are popular in counter top models, because of their mobility and easy installation. They lose less heat than gas fryers, because their heating elements are immersed in the oil and have a faster temperature recovery time between frying cycles. Gas fryers heat up more quickly and to a higher cooking temperature than electric fryers. They can be powered by either natural gas or propane, both of which are generally less expensive energy sources than electricity. This makes gas power especially popular in floor model fryers. Commercial fryers are generally available in mild steel or stainless steel. Stainless steel is less likely to corrode or stain than mild steel. Mild steel also expands under heat, which may damage the welds over time. Because of this, stainless steel fryers often come with a much longer warranty than mild steel fryers.
Some commercial fryers have a “cold zone” at the bottom of the fry pot. This is where food particles, such as breading, batter or broken off pieces of food, sink to, while the lower temperature keeps them from burning and tainting the oil. A tube-style fry pot has a large cold zone because the tubes are slightly above the bottom of the vat, leaving generous space for cooler oil and crumbs. This is particularly useful for cooking heavily breaded foods (such as a blooming onion). A tube-style fry pot is more difficult to clean than an open fry pot, but the tubes allow easy access to the heat source. Tube fryers are often less expensive than their open fry pot counterparts.
Some domestic fryers incorporate an angled motorized rotary basket that circulates its contents through the hot oil. This design reduces the amount of oil required to roughly half compared to a more traditionally designed fryer. Domestic fryers are generally much smaller than their commercial counterparts and typically have a capacity of two to four liters.