A chafing dish is a set of pans designed to keep fully cooked food hot using an arrangement similar to a double boiler, with hot or boiling water in a pan separated from the food. Crock-Pot is the brand-name for a slow cooker, an electrical appliance designed for long, slow, unattended cooking. Both chafing dishes and slow cookers use low heat. However, chafing dishes are designed to keep cooked foods hot without cooking them further, while a slow cooker is designed to transform ingredients by cooking them.
The heat source for a slow cooker is electrical. Slow cookers usually include an outer shell that heats on the inside without growing dangerously hot on the outside and a removable ceramic cooking bowl that holds and distributes heat evenly. Chafers can be electric, as well, although they more commonly use canned fuel gel to heat water in a deep pan which in turn radiates heat and warms food held in another, shallower pan that rests in the deeper pan.
Cooking and Heating
A slow cooker can be used to heat and cook raw ingredients, creating a one-dish meal. Its slow cooking time and electrical heat source is sufficient to warm and cook foods that are added cold, although preheating ingredients can speed up cooking times. Chafers should not be used for cooking or heating because the heat created by canned fuel is insufficient for bringing foods up to temperature. When using chafers, heat food in a separate pan and then transfer it to the chafing dish.
Serving and Displaying
Both slow cookers and chafers can be used for serving and displaying foods at potlucks and buffets. Caterers usually prefer chafers, which can accommodate multiple inserts of different sizes, making it possible to serve and display multiple offerings in the same pan. Slow cookers are more suitable for potlucks and family-style meals although they can also be appropriate for catering, especially if the caterer is aiming to create a homey feel.
It isn't a good idea to use either a chafing dish or a crockpot to reheat food. Both appliances heat food slowly, and their heating capacities are insufficient to reheat food quickly enough to prevent growth of food-borne pathogens. Slow cookers can cook safely unattended for long periods of time, even when you are asleep or at work. Chafing dishes that use canned fuel have an open flame and should be set up away from napkins and paper plates and checked periodically to make sure they aren't close to anything flammable.