Like the recovery boiler operation, retractable steam sootblowers are operated at maximum capacity, meaning there is no additional cleaning capacity to increase boiler availability. It is in this setting that Heat Management introduces the patented High Impact Sootblowing System (HISS™), increasing the cleaning capacity of the existing steam sootblowers by 100 %. Benefits include increasing recovery boiler availability, cleanability and efficiency, while reducing steam consumption. HISS™ provides the mill with the necessary tool, allowing safe increase of production levels beyond technical specification i.e. process more black liquor in the boiler, without jeopardizing the process availability.