The CB series of high efficiency condensing combination boilers from Noritz are designed to deliver hot water to both plumbing and hydronic heating applications, including those in colder climates. Rated at 95 percent AFUE, these units meet Energy Star Most Efficient standards. Two models are available; the CB180DV is rated at 180,000 Btu/h for hot water and 100,000 Btu/h for space heating. The CB199DV is rated at 199,000 Btu/h for hot water and 120,000 Btu/h for space heating. They deliver up to 9.2 GPM of hot water.