Abstract: A heater for use with a chafing dish having water and food pans with complemental peripheral flanges is disclosed. The heater includes a spacer sized to be interposed between such flanges to maintain at least portions of the flanges in spaced relationship. An immersible heater assembly including an upstanding arm is connected to and depends from the spacer. The heater assembly includes an encased electrical resistance heater loop having end portions connected to the arm. The arm and loop are sized to position the loop near a bottom of the water pan and immersed in water when the chafing dish is in use. A temperature sensitive switch is connected to the heater unit for interrupting a power supply when the temperature of the heater unit exceeds a predetermined temperature. A power supply cord extends from the spacer outwardly from the dish when the heater is in use.