The Columbia Keystone Series boiler is a medium to large capacity, 3-pass, dry back, Scotch marine design, packaged boiler. The three-pass boiler design delivers the best in boiler fuel efficiencies.

Keystone boilers come with many standard features which make them easy to monitor and service for decades of reliable steam or hot water. Many optional features are available for Keystone boilers, making them easy to customize to fit your unique needs.


  • 3-pass, Scotch marine boiler design
  • 150 psi section I design
  • Standard pressures: 15 psi steam, 150 psi steam, 30 psi water
  • 25 to 150 BHP
  • Six standard hand hole openings for easier servicing
  • Hinged rear cover
  • Rear Pyrex observation port
  • Arrives ready to install; fully assembled, piped, wired, and tested when the “Factory Package and Test Fire” option is selected
  • Output # per hour: 862 to 5,175
  • Length: 7 ft. 2 in. to 16 ft. 7 in.
  • Fuels: #2 oil, natural gas, LP gas, dual fuel

Available Options

1,339 - 6,695 MBH