Weil‑McLain EG‑45 – 150 MBH Cast‑Iron Gas Boiler, 84 % AFUE (Water or Steam Service)
The EG‑45 is a heavy-duty cast‑iron sectional boiler rated at 150 MBH input, providing approximately 124 MBH net for water and 110 MBH for steam applications, with a consistent 84 % AFUE. Its design supports both steam and hydronic installation profiles and can accommodate a tankless domestic hot‑water coil when ordered with the appropriate factory end‑section
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???? Key Features for Professional Installers
Cast-Iron Construction with Steel Jacket
Assembled boiler block rated to 50 PSIG, insulated jacket reduces standby heat loss.
Efficiency Enhancements
Includes automatic vent damper to minimize fuel usage during idle, and employs intermittent electronic ignition with stainless burners and combination valve.
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Dual-Service Flexibility
Water boilers include air separator, 30 PSI ASME relief valve, combination gauge, high-limit control, and low-water cutoff developments; steam units include 15 PSI relief, siphon, gauge cocks, and glass.
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Service-Friendly Configuration
Features front-access control panel, plug-in wiring harness, thermal fuse, and spill switch to streamline service tasks.
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Optional Tankless Coil Integration
Can be factory-supplied with a left-end section ready to accept a tankless domestic hot-water coil.
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???? Technical Summary
Input (MBH): 150
DOE Net Output: 124 MBH (water), 110 MBH (steam)
AFUE: 84%
Rated Pressure: 50 PSIG
Vent Size: 6″ ID chimney, minimum 20′ tall
Ignition & Control: Intermittent electronic ignition, 24 V combination gas valve, rollout fuse
Weight: ~505 lb
Jacket & Draft Hood: Insulated jacket with horizontal-to-vertical draft hood
Service Warranty: Water – 20 yr exchanger, 2 yr parts; Steam – 10 yr exchanger, 2 yr parts
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⚙️ Installation & Maintenance Notes
Vent Requirements: 6″ chimney; auto damper improves efficiency and reduces chimney loss.
Fuel & Use Flexibility: Able to operate on natural gas (steam or water) using the same block; steam version complies with all necessary relief and water safety components.
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Tankless Coil Planning: Coil must be ordered factory-equipped and cannot be retrofitted afterward.
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✅ Contractor Overview
The EG‑45 delivers cast‑iron durability with hydraulic versatility, combining steam and hydronic applications in a single unit. Automatic damper and modern ignition mechanisms reduce operating costs, while service-friendly access panels simplify routine maintenance. The optional coil feature adds DHW support without additional tank space—ideal for retrofit or new install scenarios. Its weight and design require at least two technicians for safe placement, but fit well through standard 30″ doorways in knock-down form.