The simplest types of food warmers are those that utilize the food's inherent heat and maintain the core temperature by insulating it against heat loss. Tortilla crock pots made of clay achieve this very well, as do thermoses and lined travel picnic baskets.

However, for longer periods of time, it is better to purchase a warmer that has a separate and controlled heat source. Sometimes, this heat source can take the form of steam created by a chafing dish and sterno. Another one of the most popular types of food warmers in the concession stand and catering business is the electrically powered warmer.

These food warmers are utilized for almost any product in the market, from maintaining the warmth and taste of hot dogs to keeping ice cream toppings like caramel, fudge and syrup hot and flowing. Electric coils make the food hot and pleasing to the customer, yet not so hot as to burn or overcook it. These warmers can save a business literally hundreds of thousands of dollars by keeping food safe for human consumption for hours at a time.

Safety Risks Involved with Food Warmers

The biggest threat facing food warmer users is the possibility of food poisoning. Bacteria can grow rapidly between 40° and 140° Fahrenheit. Food should never sit idly in this temperature range for more than four hours; otherwise, the food may be considered dangerous to one's health.