Experimental studies were performed on two saturated steam heat recovery systems, referred to as HRSGs. Heat recovery systems are one element of a thermal treatment (incineration) system for medical waste. The two HRSG systems were equipped with assemblies for cleaning the primary heat exchange surface on the flue gas side. The HRSG systems were analysed for energy and economy. The following factors were measured: flue gas temperature at the input and output, useful energy flux, thermal efficiency and the impact of volatile pollutants in the flue gas on the operation. The most effective system for removing contaminants from the surface of the flue gas was determined. The adopted design was compared to the construction of the HRSG systems using real parameters recorded during operation. The financial benefits, resulting from shorter stoppage times achieved through the use of an efficient cleaning system were calculated. (C) 2015 Elsevier Ltd. All rights reserved.