Though the makeup water of a low-pressure boiler is usually pre-treated the boiler is still exposed to the risk of hardness (Ca Mg etc.) leak from the feed water. Moreover when the drain of the condensate system is routed into the boiler Fe Zn ions and other hardness generated in this process will enter the boiler as well. These hardness ions lead to the problem of scale formation in the boiler. Scale formation causes deterioration of the energy efficiency and even tube failure in the worst case. Polymer-based technologies have been introduced and developed for a long time to deal with this problem. However when the hardness leak surpasses the capability of the polymeric dispersant the scale formation will still happen. Acid or chelating agents are widely used to remove these scales. But the waste has to be treated separately and the surface of the boiler may suffer from corrosion. The newly developed polymer described in this paper can work like other traditional polymeric dispersants to prevent the boiler from scaling. Its unique feature is that it can remove the scales which may be formed due to temporary excessive hardness leak. As a result it combines the function of prevention and removal of the scales. So it eliminates the maintenance interruption to remove the scales. The heating surface stays clean through the whole operation period. This polymer also proves to be very effective even in case of serious silica contamination (~1000 mg/L) so it can help to reduce the cost by allowing the system to work with small blow and thus in a highly concentrated status in non-stop mode. Furthermore by applying it to the systems in which the drain is disposed due to serious hardness or Fe contamination the drain can be rerouted into the boiler so the operation cost can be reduced. The effectiveness of this newly developed polymer has also been confirmed in over one thousand systems under operation in Japan Southeast Asian countries and Europe.