Launched in 2011, the CREST condensing boiler family offers facilities the broadest range of specification flexibility in the marketplace, Lochinvar states. The product family features 12 indoor models and six outdoor models, both ranging from 750,000 to 6 million Btu/h, and is designed, engineered and assembled in the U.S. Recently upgraded models (2.5-6.0 MBtu/h) feature an upgraded combustion system, and 316L: stainless steel heat exchanger to provide up to 96% efficiency.