The current development of large focusing heliostats to concentrate solar energy on a boiler or central receiver requires a method for measuring the overall efficiency/performance of the heliostat. A flat plate calorimeter, using the temperature rise in water at a measured flow rate, has been used to test a 22.3 - square meter heliostat focused at a distance of 31 meters. These measurements represent the first test of a large area concentrating heliostats in this country. This type of testing also established the requirement for verifying the accuracy of the collected calorimeter data. This paper presents one of the methods used to accomplish this verification. The subject method to be discussed is the use of an AGA Thermovision Model 665 for determination of temperature gradients and flux patterns on the water filled plates of the calorimeter both with and without solar beam impingement. The initial thermovision testing has established that the infrared television can be a potentially valuable tool in the assessment of flux patterns, measurement of losses within the central receivers, and eventually for determination of energy concentrations within a reflected solar beam.