Concentration of CO2 in the Atmosphere

A Fertile Opportunity for Renewable Heating

Older Commercial Building Benefits from Biomass Heat

The original, blackened, American Standard oil boiler with its six-inch stalactite pipe leaks. Photos: Scott Nichols

By Scott Nichols

Sometimes nice old buildings present fertile opportunities for renewable heating makeovers with Froling wood pellet boilers. Here is a great example. The building that became Tarm’s headquarters was a 30,000 square foot office, and the warehouse was built in stages starting in 1965 by New Hampshire Governor Meldrim Thomson for his Equity Publishing business. As Governor in the 1970s, Thomson’s business grew from the core 1965 building, and each building addition received another heating system. When Tarm Biomass moved into the building almost two decades after the Thomson family owned it, there were six separate heating systems.

The original equipment included:

  • The original, blackened, American Standard oil boiler with its six inch stalactite pipe leaks.

  • Three propane-fired rooftop units redundantly heating office space also heated by the oil boiler.

  • An oil-fired furnace array hanging from the ceiling of the 1986 high cube warehouse.

  • An oil furnace (dubbed Frankenstein) heating another 10,000 square feet. Based on oil stains and soot coatings, Frankenstein appeared to be at least 40 years old.

The Makeover Begins

When Tarm Biomass moved in as a tenant, the new building owners saw an opportunity to hire Tarm to update and simplify the heating system with a new, renewable heating system that would use Froling wood pellet boilers. With winter approaching in 2016, Tarm Biomass began a thermal makeover. They started by breaking the old American Standard cast iron sections apart and carting the soot- and mud-filled beasts to the scrap heap. Tarm then built a new distribution manifold and installed a Viessmann propane boiler where the oil boiler had been. While serving as the primary heating source in the winter of 2016-2017, the propane boiler became a backup heat source for the future.

Where the Frankenstein furnace once lived, two new Froling wood pellet boilers, 350,000 Btu/hr each, were added. A 1,250 gallon buffer tank was installed in the adjacent warehouse. The boiler installation space was chosen due to its proximity to an outside wall, allowing pellet delivery truck access and a simple chimney installation. A 15-ton-capacity pellet silo was placed just outside the new boiler room. The Froling wood pellet boilers pneumatically pull fuel through 2-inches hoses from the silo as needed, which make it unnecessary for building staff ever to handle the fuel.

These wood pellet boilers work automatically in a cascade to heat the buffer tank. Consequently, as the buffer tank drops in temperature, each boiler responds as needed to keep the tank hot. There is a Grundfos Magna circulator that automatically responds to building demand by measuring the difference in supply and return temperature. When there is a call for heat, the Magna pushes heat to the building heating-load automatically. Through flow modulation, the Magna not only saves power but also helps the buffer tank store thermal energy more effectively. Replacing the Frankenstein furnace with two new air handlers connected to the Froling wood pellet boilers was easy. Now, approximately 20,000 square feet are heated with wood pellets. Read more at .

Funding Opportunities

Using wood pellets presented several opportunities. First and foremost, the State of New Hampshire, through the Renewable Energy Division of the Public Utilities Commission, provided a generous, 40% rebate payment of just over $58,000. The United States Department of Agriculture also helped with a Rural Energy for America (REAP) grant of around $20,000. REAP information is available at .

New Froling wood pellet boiler.

Thermal Renewable Energy Credits

Until at least 2025, the building owners will be able to sell thermal renewable energy credits (T-RECs). T-RECs are marketable commodities which are worth about $22.50 per megawatt hour (MWh). T-RECs are created by New Hampshire law, which requires power generators to produce a certain amount of energy with renewable sources. If generators cannot produce their own renewable energy, they must purchase renewable energy credits. A certain amount of those credits must be purchased from the thermal class of available credits. Learn more at

Tarm installed a heat meter, tallying energy produced by the pellet boilers and uploading that data to a website. The output data is verified by a qualified third party auditor. Though the final quarter of 2017 was a warm period, the building owners generated 20 MWh’s of thermal energy, which was worth about $450.00 after paying a fee to a T-REC aggregator. Based on fuel use predictions, the building owners expect to earn between $2,000-$3,000 each year selling T-RECs. Each ton of wood pellets generates approximately 4 T-RECs in efficient pellet boilers.

During the winter of 2017-2018, locally made wood pellet heat offset about 6,000 gallons of propane use. The building owners are already exploring extending heat from the wood pellet boiler system to the last remaining 10,000 square feet oil-heated space. Stay tuned for follo-up stories about fuel use and savings.

Scott Nichols is the owner of Tarm USA, Inc. located in Orford, NH. Learn more at 1-800-782-9927.

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