A method for investigation of the parameters of X-ray beams pumped from the transmission direction into the reflection one depending on the value of applied temperature gradient is proposed. An increase in the integral intensity of diffracted X-ray beam is due to both the overthrowing effect inside the Darwin table and an increase in the angular width of beam. It is shown that it is possible to determine to a high accuracy the value of temperature gradient, beginning with which the angular width of the pumped X-ray beam increases.