The Highest Efficiencies Combination HVAC solutions created with iFLOW Hydronic Furnaces can deliver the highest efficiencies of any heating equipment in the North American industry. iFLOW holds the highest result of any combination system in North America tested to the CSA P.9-11 Combination System Efficiency Performance standard, and holds 4 of the 6 top efficiency rankings. iFLOW scored the highest efficiency of any tested combination system with the Navien NPE series at 0.98 and with the Rinnai RU160in at 0.94 CSA P .9-11 Combined Space and Water Heating Systems