The NRCB, or Noritz Residential Combination Boiler, from Noritz America allows for simultaneous residential domestic hot-water and space heating, and performs at a 95 percent annual fuel utilization efficiency. Its simultaneous capabilities are easy to control and beneficial for applications that do not store or deliver heat energy efficiently. The NRCB180DV has a maximum gas input Btu/h of 180,000 for hot water and 100,000 Btu/h for space heating. Its maximum flow rate is 9.8 gpm. The NRCB199DV has a maximum gas input Btu/h of 199,000 for hot water and 120,000 Btu/h for space heating. Its maximum flow rate is 11.1 gpm. 714-433-2905; www.noritz.com.