The high-efficiency K2 Combi condensing boiler from U.S. Boiler Company, Inc. - Burnham Brand Boilers comes in 135 and 180 mBh sizes. With its compact size and 95 percent AFUE, it is a fit for any application where propane or natural gas is available. The unit offers a 10-1 turndown ratio and a flat plate heat exchanger that provides suitable domestic hot-water performance. The Sage2.3 control and touch-screen display is easy to use. It has universal boiler vent connections for polypropylene, CPVC/PVC and flexible stainless steel. It also includes outdoor reset, pre-installed safety relief valve piping and a circulator installed inside the cabinet. It offers cool burner door technology to make servicing a hot unit easier and safer. 717-397-4701; www.usboiler.net.