Slant/Fin Galaxy Gas-Fired Hot Water Boiler- 11 HP. Model: GG-399HEC. S/N: G0017649. Natural gas only. Capacity (input): 399,000 Btuh. Output: 327,000 Btuh. MAWP (water): 100 psi. Maximum water temperature: 240 °F. Minimum relief valve capacity: 327 lbs/hr. The Galaxy boiler is one of America's most efficient and best built natural draft boilers. It's engineered for fast, simple installation and dependable operation. Watts pressure relief valve. Inlets: (4) 1-1/2 in. dia. copper tubes (from process). Outlets: (1) 3/4 in. dia. (pressure relief), (1) 3/4 in. dia. NPT (male, gas), (1) 1-1/2 in. dia. port (to process), (1) 5-1/2 in. dia. vent. Overall dimensions: 58 in. L x 37 in. W x 64 in. H.