The issues of energy saving in buildings are considered by using recuperators to save heat and cold, lost when removing air from the buildings space and transferring some of the energy to the fresh air that is supplied into the premises. Such heat exchangers can be a part of the mechanical ventilation system, as well as stand alone and carry out partial (due to heat exchange) or complete heating of fresh air (by using a heat transfer agent or an electric heater). Depending on the place of application and the recuperator type, they can have different energy efficiency or thermal efficiency, price, and respectively, energy economic indicators and payback period. Often, the developers and plants, the manufacturers go on partial deterioration o...