AquaPlus55 55 Gal. Indirect-Fired Water Heater, Residential, 210,000 BTU

Weil-McLain Aqua Plus 55 Indirect Water Heater – 55-Gallon Stainless Steel Tank for Hydronic Systems

The Weil-McLain Aqua Plus 55 is a high-efficiency indirect-fired water heater with a 55-gallon storage capacity, engineered for integration with hydronic heating systems. Designed for both residential and light commercial domestic hot water applications, the Aqua Plus 55 utilizes a high-output internal heat exchanger coil to deliver up to 210,000 BTU/hr, depending on boiler capacity and system flow rate.

Constructed with a corrosion-resistant 316L stainless steel tank and heat exchanger, this model provides long service life and reduced maintenance requirements. The unit is insulated with 2" of rigid polyurethane foam to minimize standby heat loss and improve system performance.

Core Specifications

• Storage Volume: 55 gallons
• Maximum Indirect Input: 210,000 BTU/hr
• Tank Material: 316L stainless steel (tank and coil)
• Tank Pressure Rating: 150 psi
• Coil Pressure Rating: 145 psi
• Dimensions: 60" H × 21-7/8" diameter
• Weight (empty): approx. 105 lbs

Connection Sizes

• DHW Out/In: 3/4" NPT
• Boiler In/Out: 1" NPT
• T&P Relief Valve Port: Pre-installed

Design and Application Notes

The Aqua Plus 55 is intended for vertical floor-mount installation and should be paired with a modulating or staged boiler for optimal domestic water production. The unit includes side-mounted ports for simplified piping layouts and incorporates an access port for internal inspection. All wetted surfaces are non-ferrous, making it suitable for a wide range of water conditions.

This unit is suited for high-demand residential dwellings, multifamily systems, and light commercial facilities requiring consistent hot water output and minimal recovery lag. First-hour ratings are dependent on boiler performance and loop flow rate.

Installation Overview

Installation should be performed by a licensed plumbing or HVAC professional familiar with hydronic systems. Proper isolation valves, backflow protection, and thermal expansion control must be included to meet local plumbing codes. An anti-scald mixing valve is recommended at the domestic outlet. This unit is compatible with open- or closed-loop boiler systems and must be installed with adequate air elimination to protect the coil and pump system.

Key Product Advantages

• High Recovery Capacity: 210,000 BTU/hr capability supports multiple simultaneous hot water demands.
• Low Heat Loss: Encased in 2" of dense foam insulation to improve efficiency and reduce standby loss.
• Durability: All-stainless construction minimizes corrosion and ensures long-term service life.
• Service Access: Equipped with inspection hatch for interior maintenance if required.
• Warranty: 12-year limited warranty on tank; 2-year warranty on ancillary components.

Professional Use Case

This model is ideal for boiler professionals specifying systems where performance and longevity are critical. It integrates seamlessly with Weil-McLain Ultra, Evergreen, and other high-efficiency boiler models, making it a consistent selection in mechanical room design.