Circulating Tank Heater. Fluid Capacity: 16-20 quart. 1000 Watts @ 120 Volts. The circulating tank heater is designed to keep the coolant in your engine warm. This product helps stimulate warm temperatures, gives quicker starts and protects your engine from damage that can occur during cold weather starts. New lower radiator hose connectors. Installations easier and simpler. Fits most liquid cooled engines. Equipped with check valve.