Keystone Series Boilers
Low or High Pressure Boilers
The 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.

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Keystone Series Spec Sheet
Ideal boiler for
Features
- 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
- Download the Keystone Series spec sheet for a complete list of Keystone Series features, specifications, and dimensions.
The three-pass design is a smart choice in the battle against rising fuel costs. It achieves excellent fuel efficiencies by circulating the flue gases through the boiler three times. The longer flue gases stay in the boiler, the higher the efficiency achieved.
Optional Features
- Special control requirements
- Front hinges
- Higher pressures
- Indicating lights
- Oversized supply and return connections
- Quick opening wedge pins for the rear cover
- Single electric location
- Stack thermometer
- IRI insured
- FM insured
- Non-standard voltage and hertz requirements
Talk with a boiler specialist.