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Fröling Energy Tank

The Fröling Energy Tank combines the benefits of an indirect water heater and a buffer tank into one compact, high-performance unit. Engineered for use with smaller pellet boilers, it’s the perfect solution for homes looking to maximize efficiency and comfort.

With 119 gallons of stratified thermal storage, this tank delivers modern energy management with minimal heat loss and exceptional performance.

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What Is an Indirect Water Heater?

Unlike traditional water heaters, an indirect water heater uses boiler-heated water to warm your home’s domestic water through a built-in coil, so no separate fuel source or burner is needed. 
The Fröling Energy Tank flips the script: boiler water fills the tank, while a stainless steel coil inside heats your domestic hot water. This design improves efficiency, reduces standby losses, and integrates perfectly with pellet boiler systems.

How Does the Froling Energy Tank Work?

1.

Boiler water fills the tank

The Energy Tank acts as a thermal storage unit, holding 119 gallons of hot water produced by your biomass boiler.

2.

A stainless steel coil runs through the tank

A 104-foot coil (64 sq ft surface area) circulates your potable (domestic) water through the hot boiler water—no direct contact.

3.

Heat transfers through the coil

As domestic water flows through the coil, it absorbs heat from the surrounding boiler water, producing hot water on demand without a separate burner.

4.

Stratification improves efficiency

A built-in baffle keeps hot water at the top and cooler water at the bottom, so the system delivers consistently warm water where and when it's needed.

5.

Hygienic, efficient performance

High turbulence inside the coil prevents scale buildup, reducing maintenance and extending system life.

With or Without Stratification Baffle?

Even in well-insulated tanks, water layers can mix and reduce efficiency. Fröling's internal stratification baffle solves this by maintaining a sharp boundary between hot and cold zones. You can compare both in the table below:
Without Stratification Baffle
In tanks without a stratification baffle, hot and cold water mix freely. This blending dilutes stored energy and lowers the overall temperature. As a result, the boiler must cycle on more often, reducing efficiency.
With Stratification Baffle
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A built-in stratification baffle keeps hot water at the top and cold water at the bottom. This thermal layering maximizes usable energy and maintains higher output temperatures. It also lets the boiler stay off longer between cycles, improving performance.
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Key Specifications & Features

The Fröling Energy Tank combines innovative design with durable materials to deliver long-lasting, high-efficiency hot water storage. Every detail, from the coil surface to the insulation, supports optimal heat retention and seamless boiler integration.

  • One size 119 Gallon Carbon Steel Tank
  • Corrugated Stainless Steel Coil Creates 64 sq ft of Heating Surface
  • Removable Insulation Results in Losses Less Than ⅓° Fahrenheit per Hour 
  • Strategically Sized and Located Tappings
  • Perfect for Fröling PE1 model 20 or other small indoor wood boilers and pellet systems similar size.
  • Sensor Bar Holds Many Sensors at Various Positions 
  •  5 Year Warranty - Made by Fröling

Learn More with Our Downloadable Brochures

Fröling Energy Tank Brochure - file size 2 Mb

DOWNLOAD HERE
Energy-tank-manual

Energy Tank Installation Manual - file size 897 Kb

DOWNLOAD HERE

Benefits & Performance

Reduces Boiler Cycling
Stores extra heat to prevent frequent on/off cycles, improving efficiency and extending boiler life, even in larger commercial wood boiler setups.
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Reliable Hot Water at Low Temps
Delivers consistent hot water, even when boiler output is lower, ideal for pellet systems that modulate.
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Fast Hot Water Recovery
Provides up to 103 gallons of hot water in the first hour, meeting DOE performance standards.
Supports Heating & Hot Water
Serves both domestic hot water and space heating needs, with a design that minimizes Legionella risk.
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System Integration & Installation

  • Connects easily downstream of small (≤25 kW) pellet boilers or similar sized systems.
  • Plumb vertically, near boiler with insulated lines; follow local plumbing codes.
  • Use dedicated circulator or valve to direct boiler flow through tank coil.

Domestic Performance

Enjoy steady, efficient hot water without relying on gas or electric heating elements.
  • High First-Hour Output:
Delivers up to 103 gallons of potable hot water in the first hour (DOE standard)..
  • Consistent Temperature:
Maintains 140 °F or higher for domestic hot water and appliance demands.
  • No Extra Energy Source Needed:
Operates without electric or gas elements — cutting energy use and costs.

Common Applications:

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Commercial Buildings:

Support zone heating, balance system loads, and integrate with multiple heat sources like solar thermal or heat pumps.
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Renewable Integration:

Pair with solar thermal or hybrid systems to store intermittent energy and maintain consistent heat delivery.

FAQs about Froling Energy Tank

Fröling Energy Tanks are built to last with carbon steel construction and removable insulation. With proper installation, you can expect decades of reliable performance.
Pricing varies depending on your system setup and installation needs. Contact us for current pricing and to get a personalized quote based on your project.
It depends on your goals. If you want steady domestic hot water and better boiler efficiency, an indirect water heater like the Fröling Energy Tank offers both DHW and thermal storage in one. A buffer tank alone won’t deliver domestic hot water.

Shop Wood Boiler Parts

Need valves, sensors, or fittings for your system? Browse our full selection of high-quality wood boiler parts, ready to ship and built to last.
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What Our Clients Say About Us

Angela says:
“Happy with our new wood pellet boiler. While it is very expensive to install this boiler, both state and federal rebates may be available. Also, over the long term it is much cheaper to heat with pellets than gas or oil. Froling was great to deal with. Professional, responsive, on time. Definitely recommend Froling and their products.”
Gretchen says:
“Great experience when they installed my residential pellet boiler. All the workers were very respectful, neat and polite. Mark and everyone was so helpful in the process of planning and getting this done, on time, with minimal disruptions.”

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