You are here: Home > Hydronic Heater Replacement Parts > Triangle Tube Heater Parts > Keystone KS/KW
Choose a sub category:
KS 399 KW 199 KS 500
KW 285 KS 600 KW 399
KS 750 KW 500 KS 850

High Efficiency Condensing Boilers from 399 to 850 MBH

Keystone Condensing Boilers provide powerful solutions for large residential and light commercial applications with 5 models with inputs from 399 to 850 MBH. These products feature a stainless steel heat exchanger with a thermal efficiency between 95 and 97%. Their compact design minimizes floor space while the cabinet provides easy access to all components. The large user friendly control interface makes set-up easy. The advanced control modulates the boiler with a 5 to 1 turndown ratio. Up to 8 boilers can be joined in a cascade while the control features parallel modulation and boiler rotation to maximize efficiency and service life.

Keystone Condensing Boilers from 500 to 850 MBH are CSD-1 compliant as a standard feature. This saves both cost and installation time


  • Energy efficient with 95% to 97% Thermal Efficiency
  • Stainless Steel Heat Exchanger
  • CSD-1 Standard on 500 to 850 MBH Boilers
  • Integrated Cascade
  • Multiple pump control and thermostat inputs
  • 5 to 1 Turndown
  • 75 psi Pressure Relief Valve on Keystone Boilers