Abstract: An integrating flow calorimeter for measuring and indicating the cumulative heat exchanged between a load equipment and a heat-conveying liquid circulating therethrough.A flow measuring device continuously measures the quantity of liquid circulated through the load equipment, and closes a switch for a predetermined fixed interval of time each time a predetermined quantity of the liquid has been supplied to the load equipment. The switch connects a differential temperature measuring device to an electrical power source, which can be a battery mounted integral with the meter.The differential temperature measuring device includes temperature sensors which sense the temperatures of the liquid supplied to, and exhausted from the load equipment.