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Effortless comfort, Maximum Efficiency
AquaBalance® Series 2

The Weil-McLain AquaBalance® Series 2 is a compact, high-efficiency boiler ideal for residential and light commercial use. With up to 95% AFUE, it offers both combi and heat-only models, delivering reliable space heating and domestic hot water. Key features include a durable stainless steel heat exchanger, ENERGY STAR® certified, and low NOx emissions.
Features
FLEXIBLE SIZING
- Available in 80, 120 and 155 MBH inputs sizes
- All 3 sizes available in heat-only, or combination space and domestic hot water heating versions
DURABLE DESIGN
- 1″ diameter ASME certified 316L stainless steel single tube heat exchanger – low pressure drop
- Heavy gauge insulated jacket – provides quiet operation
HIGH EFFICIENCY
- 95% AFUE energy efficiency
- Low NOx SCAQMD compliant
EASY INSTALL / MAINTENANCE
- Contractor-friendly removable sides
- Pre-wired, plug-in ready electrical design
- Commercial grade 120V power 6′ cord with 3 prong plug
- Wall mounting bracket and hardware
Venting
- Unique “3-in-1” vent adapter – readily accepts PVC, CPVC, SS or PP vent materials
- Multiple vent options – direct vent, 2 pipes or concentric, through roof or sidewall
USER-FRIENDLY CONTROL
- Digital Honeywell boiler control
- Easy to read display with simple status icons
VERSATILE HEATING
- Natural or Propane (LP) gas operation – shipped as NG, optional LP conversion kit available
- 4 gallons per minute DHW 155 combi (70-degree rise)
- Internal 3-speed Grundfos circulator (combi versions only)
EXTENDED WARRANTY
- 10 year limited warranty heat exchanger for residential use
- 5 year limited warranty heat exchanger for commercial use
- 2 year limited warranty all other parts
SEE In ACTion
big on warmth, low on energy use
Engineered for comfort, designed for efficiency
Certified ENERGY STAR® and heat pump ready, this high-efficiency boiler delivers powerful, eco-friendly performance while keeping energy costs low.


Technical Specs
MODEL | AFUE (%) | CSA INPUT (MBH) | NET (MBH) | DOE HEATING CAP. (MBH) | VENT MATERIAL | APPROX. SHIPPING WEIGHT (LBS.) | VENT SIZE (IN.) |
---|---|---|---|---|---|---|---|
Combi AB-80C | 95 | 80 | 65 | 75 | PVC, CPVC, PP, SS | 77 | 2-3″ |
Combi AB-120C | 95 | 120 | 97 | 112 | PVC, CPVC, PP, SS | 80 | 2-3″ |
Combi AB-155C | 95 | 155 | 125 | 144 | PVC, CPVC, PP, SS | 87 | 3″ |
Heat-Only AB-80H | 95 | 80 | 65 | 75 | PVC, CPVC, PP, SS | 64 | 2-3″ |
Heat-Only AB-120H | 95 | 120 | 97 | 112 | PVC, CPVC, PP, SS | 67 | 2-3″ |
Heat-Only AB-155H | 95 | 155 | 125 | 144 | PVC, CPVC, PP, SS | 67 | 3″ |
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