Ultra Model (Hard Water) The Ultra Model fulfills the special demands of hard water environments through its sophisticated heat exchanger system which successfully avoids scaling. Being one of the most accredited solar water heater manufacturers, we ensure our products are blockage-free technology provides uninterrupted flow even in extremely harsh water conditions, and corrosion-resistant construction further increases the lifespan of the system. The jacket-type heat exchanger provides optimal performance in tough environments, combined with an aluminum anode having provision for built-in replacement. This model is designed particularly for regions where the hardness of water creates major problems for traditional water heating systems.