Use of low-temperature energy accumulated in the ground for heating buildings requires the borehole heat exchangers. The amount of heat exchanged (by the heat exchanger with the urethane) depends on the construction material parameters used to make the exchanger. One of the problems with the efficiency of the heat exchanger is the amount of heat transferred between the borehole pipes. This phenomenon can be described using numerical simulations or by studying a laboratory model. This article shows the results of laboratory measurements of the heat flux permeating between the pipes of the heat exchanger.