Plymouth Ultra Series Boiler ,   Model: WPSB Additional Information Dunkirk's Plymouth Ultra (WPSB) Boiler offers the best combination of heating comfort, efficiency, reliability and affordability making it one of America's Hottest Boiler Values. With efficiency as high as 84.1%, a Plymouth Ultra boiler is an outstanding choice for performance and low operating cost. Efficiency: Mid-Efficiency Capacity: 75 - 112.5 - 150 - 187.5 - 225 - 262.5 - 299 MBH Heat Exchanger: Cast Iron Combustion: Atmospheric Venting: Vertical Vent Boiler Type: Hot Water Brochure 240005052 - WPSB Rev. 9/06 264.1 kb Installation & Operation Manual 14683011 - WPSB Rev. 2.1 1.8 MB Service & Technical Guide Dunkirk Radiation Tables 96.2 kb Warranty 1595019 - WPSB Rev. A 661.1 kb