Rheem’s Prestige High Efficiency Natural Gas Combi Boiler provides an efficient, continuous supply of domestic hot water used for faucets, showers, washing machines, etc.) and provides hydronic space heating for residential applications such radiant floors, baseboards, hydronic air handlers, etc. As a condensing combi boiler, heat is extracted from the units exhaust gases, allowing for higher efficiency and therefore helping you save on energy costs. With room air intake and the ability to use to use PVC venting, you can save considerable costs in venting materials and installation labor. Its 95% AFUE qualifies for valuable state and local rebates in select areas. professional sizing and installation recommended.