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Weil-Mclain 133-041-304 LGB-4 400 Input MBtu 85.1% AFUE Commercial Natural Gas Water Boiler Series 2


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Retail : $9,857.00 - $2069.97 =
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Product details

Weil-Mclain 133-041-304 LGB-4 400 Input MBtu 85.1% AFUE Commercial Natural Gas Water Boiler Series 2

  • Short draw rods permit faster, easier assembly of boiler sections
  • Includes factory-assembled base and burners, and simplified piping for quick and easy installation
  • Compact design allows for more piping and venting headroom
  • The highest efficiency commercial cast iron atmospheric gas boiler available by Weil-McLain
  • Built-in air separator diverts air to the expansion tank
  • Gas natural draft water and steam boiler with cast iron sections




  • Combination operating and high limit temperature control (LGB™-4 thu 20 only)
  • Operating temperature control (LGB™-21 thru 23 only)
  • High limit temperature control (LGB™-21 thru 23 only)
  • Combination pressure temperature gauge
  • 30 PSI ASME relief valve-side outlet
  • Built-in air eliminator in end sections
  • Probe-type low water cutoff, PS-851-120 (packaged only)


  • WFFP control panels (LGB-6 thru 23)
  • WMBC control panels (LGB-5 thru 23)
  • Probe-type low water cutoff, ps-851-120 (non-packaged water only)
  • Factory-assembled sections (LGB-4 thru 14 only)
  • Fire-tested packaged unit (LGB-4 thru 14 only)
  • 1½" Inspection tappings with brass plugs — two for each section
  • 80 PSI working pressure test of sections
  • Water level controls and low water cutoffs
  • Low-high-low firing (LGB™-6 thru 12 only)
  • Stage firing (LGB™-13 thru 23 only)
  • Energy management control systems (BCP panels)
  • IRI, FM and CSD-1 control systems
  • Natural gas to propane gas conversion kit
  • W-M and PLUS indirect-fired water heaters
  • W-M Maxiflo pool heaters
  • W-M brazed plate heat exchangers


  • WFFP-1 Panel (LGB-6 Thru 12)
  • WFFP-2 Panel (LGB-13 Thru 23)
  • 30-second time delay relay (two on WFFP-2)
  • Two 24-volt DPDT relays (four on WFFP-2)
  • Terminal block
  • Fuse (two on WFFP-2)
  • Toggle switch
  • Four Indicator lamps (eight on WFFP-2)


  • Alarm bell and transformer for remote indication of flame failure
  • Alarm bell – panel mounted
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Specification Sheet

Basic Information
MPN ? Manufacturer Part Number 133-041-304
Manufacturer Weil-McLain
Series ? A manufacturer's grouping of items that match, coordinate, or complement each other. LGB Series 2
Dimensions and Measurements
Weight ? Weight 1,185.00
BTU Input 400,000
AFUE 85.1%
Tank Capacity 36.5 gallons
Height (Inches) ? The vertical measurement from bottom to top, measured in inches. 50-3/8"
Width (Inches) ? The horizontal measurement from left to right, measured in inches. 21"
Characteristics and Features
Material ? The material(s) used in the construction of the product. Cast Iron
Boiler Type Commercial
Fuel Type Natural Gas
Venting Chimney Vent
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