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Williams & Davis – 4000W Series Scotch Marine Boiler

Output: 30 to 1,500 HP (294 to 14,715kw) 1.2 to 50MM Btu/hr
Sizes 15 HP through 1,500 HP
Gas, Oil or Combination
Firetube Hot Water & Pressure Steam Boilers

4-Pass Water-back
Low Radiant Heat Losses
High Gas Velocities
High Efficiency
Space Saving Design


The Williams & Davis Series 4000W is a traditional 4-pass, water-back horizontal firetube boiler that offers high efficiency, flexibility, reliability, safety and ease of operation. Series 4000W provides high flue gas velocities and low stack temperatures to maximize its performance. All units are factory fire tested and shipped as an integrated package, ready for quick connection to utilities. Built to exceed ASME standards, the Series 4000W positions itself well above its class. This is a company principle that continues to make W&D a top choice in the industry.
  • Engineered and built in accordance with the latest ASME Boiler Codes.
  • McDonnell & Miller combination pump controller and primary low water cutoff.
  • Completely wired and piped for service connections.
  • Fully modulating burner operation.
  • Premium 2″ thick high-density insulation.
  • “Off-the-Shelf” industry standard parts used where possible for serviceability.
  • Probe type auxiliary low water cutoff.
  • Epoxy painted 20ga galvanized steel jacket.
  • Solid state Honeywell combination pressure control, automatic operating control, manual reset control.
  • Exceeds industry standards for heating surface area for exceptional efficiency.
  • Pressure tested to 1.5X operating pressure (225psi for 150psi vessels).
  • Flanged exhaust stack – includes additional flange for installation.
  • Furnace diameters and combustion area volume optimized for Lox NOx operation.

Standard Available Options:

  • Customizable controls and connections
  • Additional hand holes and manway access
  • Davited front and rear doors
  • Burner make and model
  • O2 Trim System
  • “Linkage-less” Modulation


The Williams & Davis 4000W fortifies their everlasting reputation for building the most rugged and serviceable scotch marine boiler in the industry. The 4000W further offers a high efficiency design built to maximize flue gas velocities and transfer as much heat energy as possible to the process water instead of exhausting it through the stack or radiating heat into the boiler room. Through stringent and methodical building practices perfected over almost 90 years in the industry, Williams & Davis guarantees each of their boilers will meet, and typically exceed, every ASME standard. All units are operationally tested and shipped as an integrated package when practical, ready for quick connection to utilities. As such, they demonstrate their confidence in their boilers by offering the industry’s best pressure vessel warranty of 10 years (25 year available) with an approved water testing and treatment program.


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