375,000 BTU Output Keystone Condensing Boiler Zoom

375,000 BTU Output Keystone Condensing Boiler


Brand: Triangle Tube

Triangle Tube
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Non-Stock ItemAllow 7-10 Days to Ship Out



Fuel Type: Propane
Natural Gas
Vent Type: Direct Vent
System Type: Hydronic (Water)
Gas Connection: 3/4"
Features: Condensing
EI/Spark Ignition
Water Connection: 1-1/4"
Air Intake: 4"
Vent Diameter: 4"
BTU Input: 399000
IBR Rating:
Combustion Efficiency: 95.6
Height (Inches): 38
Width: 24-1/2"
Depth (Inches): 31"

Description for Triangle Tube KS399

Note: Product Title reflects this boiler's IBR Net Output Rating

Triangle Tube's Keystone Series Condensing Boilers are designed for large residential and light commercial applications. The stainless steel heat exchanger and burner provides high efficiency, low emissions, and a high turndown to minimize short cycling. With maximum inputs of 850 MBH for boilers and 500 MBH for water heaters, the Keystone series can meet most needs with a single unit. For larger requirements the advanced control allows units to be joined and function with parallel modulation for maximum efficiency.


  • 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

    PLEASE NOTE: The product weighs 346 lbs. and may require the use of a
    lift gate.
    If you do require a lift gate at your delivery, you'll have the option to add this FREE of charge when you checkout.
  • 375,000 BTU Output Keystone Condensing Boiler

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