Commercial Condensing Boiler; Type Hot Water; Supply Connection 1-1/2 Inch Male Threaded; Return Connection 1-1/2 Inch Male Threaded; Gas Type Natural/Propane; Gas Connection 1 Inch Threaded; AGA Input Rating 399000 BTU/Hour; DOE Heating Capacity 386000 BTU/Hour; Net IBR Rating 336000 BTU/Hour; Air Inlet Connection 4 Inch; Boiler Dimensions 21-21/32 Inch Length x 23-31/32 Inch Width x 61-9/16 Inch Height; Boiler Material Stainless Steel; Water Content 4.5 Gallon; Venting Type Direct; Vent Size 4 Inch; Relief Valve Details 30 PSI Pressure Relief Valve Installed; ASME Code Yes; Pressure Rating 80 PSI; Mounting Type Floor Mount; Warranty 10 Year (Heat Exchanger); Options Adapter; Applicable Standard ASME H, AHRI, CSA (Canada and US); Electrical Rating 120 Volt AC 60 Hertz 1-Phase 4.5 Amp Full Load; Turndown Ratio 5:1; Noise Rating 47 Decibel; Maximum Operating Temperature 194 Deg F; Water Connection 1-1/2 InchThe Buderus SSB residential boilers were designed with the same high-quality components found in our commercial SSB boilers, but in a compact space-saving design. All SSB boilers include integral pumps, built-in low water cut-offs, adjustable manual reset high limits, push-terminal wiring and a host of venting options. In addition, the Buderus SSB residential boilers have the best price-performance and warranty in the market. The 316L stainless steel heat exchanger, is a water-tube design that has no welds on the water side of the heat exchanger. This feature, combined with a 5:1 turndown pre-mix burner, allows the SSB boilers to achieve an AFUE rating of 96%. Other standard features include outdoor reset, domestic hot water priority, top connections which allow for an easy installation, limited clearance requirements, internal cascade sequencer for up to 8 boilers for increased output and application design, and CSD-1 components pre-installed.