AquaPlus45 40 Gal. Indirect-Fired Water Heater, 190,000 BTU

Weil-McLain Aqua-Plus 45 Indirect-Fired Water Heater – 40 Gallon Stainless Steel DHW Tank

The Weil-McLain Aqua-Plus 45 is a 40-gallon indirect domestic water heater designed for integration with hydronic boiler systems. Utilizing a high-output stainless steel heat exchanger coil, this unit delivers 190,000 BTU/hr of indirect input capacity with a fast recovery rate and reliable hot water delivery. It is suitable for medium- to high-demand residential or light commercial applications where boiler-supplied domestic hot water is required.

This model features a high-grade stainless steel tank and coil for corrosion resistance, an insulating thermal shell to limit standby losses, and an efficient coil design that supports reduced head loss for consistent performance across varying system loads.

Performance Highlights

• Storage Capacity: 40 gallons nominal
• Heat Exchanger Output: 190,000 BTU/hr
• Pressure Ratings: Coil – 145 psi; Tank – 50 psi
• Tank Construction: 316L stainless steel inner tank and coil
• Head Loss: 3.3 ft at 10 GPM

Connection and Physical Data

• DHW Connection: 3/4" NPT
• Boiler Supply/Return: 1" NPT
• Unit Height: 46-1/4"
• Tank Diameter: 21-7/8"
• Dry Weight: Approximately 90 lbs

Design & Installation Considerations

This indirect water heater is engineered for vertical installation and must be paired with a properly sized boiler system. The low-pressure drop coil and well-insulated tank body help minimize energy loss while maximizing first-hour delivery and sustained recovery. Units are shipped with factory-installed temperature and pressure relief valve (T&P). An external mixing valve is recommended for domestic outlet temperature control.

Professional installation is recommended to ensure correct integration with the hydronic loop, proper boiler controls, and compliance with local code requirements. Units should be isolated with appropriate valves to facilitate servicing without system disruption.

Product Advantages for Installers

• Corrosion-Resistant Construction: 316L stainless steel components reduce the risk of premature failure due to scale or water chemistry issues.
• Compact Footprint: Cylindrical vertical tank design optimizes use of mechanical room space.
• Fast Recovery Rates: Suitable for households with high peak demand or simultaneous fixture use.
• Extended Warranty: 12-year limited on tank; 2-year on all other parts.

Intended Applications

The Aqua-Plus 45 is appropriate for mid-size residential applications requiring reliable indirect domestic hot water from a boiler loop. It's especially effective in systems designed with modern high-efficiency boilers that benefit from reduced cycling due to high-volume indirect tanks.