A rethermalizer works to heat up pre-packed foods from a chilled or frozen state of less than 40 degrees F to a temperature of more than 165 degrees F safely and quickly. This equipment, which encompasses water baths, combi ovens and cook-and-hold ovens, can heat a variety of food items, including soup, gravy, sauces, pasta, meats and vegetables.

Unlike food warmers, rethermalizers bring foods out of the danger zone, which encompasses temperatures between 41 degrees F and 135 degrees F, quickly to adhere to HACCP requirements.

With water bath rethermalizers, foodservice operators pre-cook ingredients, place them in a vacuum-sealed package and then freeze the food. Staff then places the frozen food items into the hot water tank for heating. Water transfers heat, and this method requires no convection or moving air. Operators can simultaneously cook all types of menu items in these units.

Water baths are categorized by capacity or volume. Operators can choose from countertop and floor versions, depending on their needs. Countertop types hold about 7 gallons of product compared with floor models, which have about a 12-gallon capacity, depending on the model.

Input rate and Btus are not a factor with water-bath rethermalizers as these units typically recover temperatures quickly after heating. This is because the temperature is generally set lower than with ovens at between 165 degrees F and 180 degrees F. It’s important to note that although product will get within 10 degrees of the desired temperature using this method, it can take significantly longer for items to get to the water-bath thermostat’s set temperature.

Water-bath rethermalizers work well for a variety of applications but are geared for operations with long dining hours that need to hold products for extended periods. This is why they’re a popular choice for hotels with long room service hours or fast-casual restaurants that cook product ahead of time. There also has been an increase in use of this rethermalizer type in the healthcare and school segments.

These units typically come standard with an automatic water fill feature that ensures the water level remains at the correct height and have options for timers that can be set in different ways, such as with a reheat and hold time.

In terms of options, some manufacturers provide separation mechanisms for inside the water tank since leaving space between the food bags during rethermalizing allows for more efficient heat transfer and faster heating times.

The many high-efficiency improvements made with fryers have been carried over to water-bath rethermalizers. This has resulted in more reliable combustion systems for gas models that save energy.

In addition to water-bath rethermalizers, most combi ovens have rethermalization capabilities.