The choice of rational heat-utilizer heating scheme is a very current problem of energy saving when using boiler units. This article proposes the heat computation technique of heat exchanger at heat pipes with deep combustion - product cooling in boilers and water steam condensation. In addition, the construction scheme of heat exchanger made with two units in which the heat pipes are filled with different working medium is described. The numerical study results of heat carrier temperature and pressure distribution, namely: combustion products and water being heated according to counterflow - heat exchanger length are presented. The efficiency of two-phase heat-utilizer is determined.