Firetube Condensing Boiler

Models: SL725, SL850, SL1000, SL1500, SL2000, SL2500, and SL3000

Patterson-Kelley is excited to introduce their very first firetube boiler, the P-K SOLIS®! This top-of-the-line, highly efficient condensing boiler is designed to maximize comfort without sacrificing savings or floor space. Each P-K SOLIS® model features a unique geometric design that optimizes heat transfer, resulting in efficiencies of 97%, 10:1 mechanical turndown, and ultra-low NOx emissions.


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General Documents

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Standard 10:1 Mechanical Turndown

10:1 Turndown Technology Increases Efficiency and Reduces Operating Cost

Patterson-Kelley has achieved higher turndown with a unique mechanical process that allows the gas valves to control boiler performance without increasing excess air. This results in building flexibility and efficiency.

This method delivers a 10:1 turndown rate while preserving a high dewpoint, which helps maintain high condensation levels. This higher turndown capability will provide designers the ability to match input to building loads without sacrificing efficiency and reliability.

Simplified Serviceability

The heat exchanger is designed to provide simplified and quick annual maintenance. The top of the heat exchanger opens, providing full access to the tubes and burner inside the unit. This makes any maintenance, including cleaning, a quick and cost-effective process.

NURO® Touch-Screen Control System

Turndown energy usage


All of our boilers are equipped with the most intuitive interface in the industry, the NURO® Touch-Screen Control. Designed to maximize efficiency, the NURO® Control System monitors and modulates the combustion and ignition of the boiler to maintain the desired outlet temperature.


  • 725 – 3000 MBTU (Natural Gas)
  • Up to 97% thermal efficiency
  • 10:1 mechanical turndown
  • 316 SS tube and tube sheet
  • 304 SS heat exchanger shell
  • Narrow footprint fits through a standard 36” doorway!
  • Hinged and removable doors allow for quick access to firetubes and burner for easy maintenance
  • Zero-clearance capable for side-by-side installation
  • The simple-to-use NURO® touch-screen technology adjusts boiler controls and settings with the swipe of a finger
  • Ultra-low NOx emissions

Contact us to learn more about the Patterson-Kelley difference.

Contact Patterson-Kelley