Rheem Water Heating now offers computer software specifically intended for sizing tankless water heaters for residential and commercial installations. Based on the CertiSpec3 software for Rheem-Ruud commercial water heaters, the new EZ-Spec tankless software application is now available for download at www.rheemtankless.com in the “Products” menu. EZ-Spec offers drop-down menus and easy-to-understand fields, and incorporates the specific flow rates for an array of residential and commercial hot-water appliances.