• UB90 Condensing Boiler

    UB90 Series 4

UB90 Series 4 Condensing Boiler


The UB90 Series 4 condensing boiler offers a 90% AFUE efficiency rating in a small compact design ideal for low clearance/limited space applications. It features a high efficiency cast aluminum heat exchanger with low pressure drop, hot surface ignition (HSI) boiler control and a Hydrolevel combination high limit/low water cut off control with a boiler water temperature reset feature. A stainless steel premix burner provides corrosion resistance and longevity. The UB90 is a sealed combustion boiler which is approved for polypropylene venting and includes an induced draft blower with adjustable exhaust (front, right side or rear). This unit has a 15 year limited warranty.


  • 90% AFUE:  Energy Star
  • Heat Exchanger: Cast Aluminum
  • Combustion: Sealed Combustion
  • Venting: Direct Vent
  • Boiler Type: Hot Water
  • Boiler Control Module: HSI Integrated Boiler Control
  • Combination Hydrolevel High Limit and LWCO with boiler water temperature reset feature
  • Heat Exchanger: Cast Aluminum Heat Exchanger
  • Combustion: Stainless Steel Premix Burner
  • Induced Draft Blower with adjustable exhaust (front, right side or rear), Inducer Motor Assembly includes 5’ schedule 80 2” CPVC and CPVC Tee
  • Electrical: Junction Box, Transformer and Wiring Harness
  • Textured painted steel jacket
  • Other: Temperature/Pressure Gauge, 30 PSI Safety Relief Valve, Pressure Switch(es), Low Profile Condensate Trap, Air Vent and Leveling Legs.


  • Natural Gas or Propane
  • Taco or Grundfos Circulator


Easy to Install & Service

  • Choice of multiple supply and return locations (top, side or combination)
  • Leveling legs
  • Junction Box provided
  • Removable control panel for quick access
  • Low profile condensate trap provides easy plumbing of condensate drain lines

Documents / Resources

Current Documents
Archived Documents


User Manual

Installation & Operation Manual

Parts Lists


Technical Bulletin

Product Bulletin



Service Bulletin

Kit Instruction

Engineering Documents / Resources

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