Thursday, July 27, 2017

Featured T4 Installation at the Marsh-Billings-Rockefeller National Historical Park

Boilers: Fröling T4 150 (500,000 Btu/r) wood pellet/wood chip boiler.
Previously installed Garn WH1500 (177,000 Btu/hr) with a water capacity of 1,420 gallons.
Thermal Storage: The Garn’s water capacity is used as the thermal buffer tank.
Fuel Storage: 20’ shipping container modified for fuel storage
Fuel Delivery: Modified P4 cyclone (day hopper) suction device.
Sold and Installed By: Sunwood Biomass of Waitsfield, VT | 802.583.9300 |
Location: Marsh-Billings-Rockefeller National Historical Park | 54 Elm Street | Woodstock, VT 05091 |

There is a mandate to invent an entirely new kind of park. It must be one where the human stories and the natural history are intertwined; where the relatively small acreage serves as an educational resource for the entire National Park Service and a seedbed for American environmental thought; and where the legacy of American conservation and its future enter into dialogue, generating a new environmental paradigm for our day. (John Elder, author and Middlebury College Professor Emeritus, From a speech at the opening of the Marsh-Billings-Rockefeller National Historical Park, June 5, 1998).

Tarm Biomass has had the privilege of providing two boilers for Marsh-Billings-Rockefeller National Historical Park, in Woodstock, VT. We applaud the National Park Service for its efforts to prove the value of an environmentally sustainable National Park System. This post is about the most recent installation of a Fröling T4 150 automatically fed and fired wood pellet boiler for heating a 30,000 square foot mansion at the park.

There are two boilers housed in the Mansion’s garage, which are used to heat approximately 30,000 sq. ft. The Garn wood boiler was installed a few years ago and reduced the Mansion’s oil consumption by about 50%. With the new Fröling T4 150 boiler installed, there is no fossil fuel consumed at the Mansion. Previously, the Mansion consumed 33% of the oil used at the park.

There were two unique challenges with the installation of the new T4 150. Both challenges were caused by a lack of space for bulk wood pellet storage and for a thermal buffer tank in the garage. Yet, the Park Service could not allow for the construction of additional buildings.

With the help of National Park Asset Management, LN Consulting, and the installing contractor, Sunwood Biomass, a plan was developed. A portable 20’ cargo container was chosen for the wood pellet fuel storage. The storage container ingeniously includes sloped floors, a Fröling suction screw auger system, fuel level sensors, fill connections, and all necessary safety devices. Because the Park Service also did not want the wood pellet fuel container visible during the busy summer season, the wood pellet fuel container is removed between early spring and late fall. To remove the wood pellet container easily, quick disconnects for both fuel and electrical were installed. Normally the Fröling T4 150 is not equipped for pneumatic delivery of wood pellets, but a hybrid fuel delivery system was created using portions of the fuel delivery system from a Fröling P4 pellet boiler. Pneumatic fuel conveyance through small, flexible hoses makes disconnecting the fuel lines a snap. The fuel storage container was even painted forest green and adorned with Park Service emblems.

During the summer, the Garn wood boiler is used for domestic hot water and any small heating needs.

The second challenge, including an adequate thermal buffer tank to improve boiler performance, was met by utilizing the built-in water storage of the Garn wood boiler. The Fröling T4 operates best with approximately 1000 gallons of buffer, so the 1,500 gallons in the existing system was a perfect solution.

There is one other Fröling boiler installed in the park. In 2013, a Fröling P4 32/38 wood pellet boiler was installed in the Double Cottage building, which includes two staff housing units. The P4 replaced an aging oil boiler and furnace. The building is now entirely free of fossil fuel.


The Marsh-Billings-Rockefeller Mansion


Alternate view of boiler house and pellet container

A view of the Mansion’s garage that houses the boilers and the pellet fuel container

Pellet container being moved

Pellet container being off-loaded

Combination of container images

Three views of the pellet container showing fill and building connections

Photo of inside of pellet container

Inside view of the pellet container

Full view of boiler house with door open showing boilers

Front View of garage housing the boilers

Front view of boiler and feed system, Garn in background

A closer view of the Fröling T4 Boiler

Close up of cyclone on feed auger

A close-up view of the pellet suction and day hopper

Tuesday, February 14, 2017

Hydronics for High-Efficiency Biomass Boilers Training

Update! The correct date and information for the upcoming NYSERDA boiler training. It seems our email subscription feed hiccuped and sent out an old post from 2015.


Friday, January 6, 2017

Featured Installation: South Main Apartments-Waterbury, VT

36 State Drive, Waterbury

The historic Ladd Hall in Waterbury, VT has gone through a huge makeover. The building was sitting vacant since August 2011, when Tropical Storm Irene hit and flooded the basement. The original  building was bult in the 1890’s with a wing added in the 1950’s to house nurses working at the state hospital. The building was then later used for offices for the state.

Building Information:


The original front brick building was converted into 2 3-bedroom apartments and a one bedroom apartment on the third floor. The 1950’s addition was totally demolished and replaced with new construction to house 23 more apartments (twelve1-bedroom and eleven 2-bedroom). The new wing is where the new heating system is located and is built to high energy efficient standards. The total square footage is 28,000 Sq. Ft. Building owned and operated by Downstreet Housing and Community Developement located in Barre, VT.

ladd-hall1  Architectural Rendering

                                   Waterbury South Main Apartments

                                                                                                   Completed View of New Construction Wing 

Heating System:  IMG_3071

The new heating system comprises of two 350,000 Btu/hr Fröling P4 pellet boilers with 900 gallons of heat storage. Heat storage allows allows efficient heating of Domestic Hot Water year-round and efficient boiler. The building has NO fossil fuel back-up boiler. The pellet boilers are estimated to offset approximately 10,000 gallons of heating oil annually. The boilers are connected to a 20 ton interior pellet store room. Each boiler has it’s own suction auger delivery device.

Heating System was designed by Trevor Parson, Engineering Services of Vermont, and Sunwood Biomass. Installed and manitained by SunWood Biomass, Waitsfield, VT. 802-583-9300














Viewing window for the pellet store room. The squeegee looking device is actually using a magnet to keep the glass free from dust.


Pellet fill connections.


We like the placards.


The original building.


The new wing housing 23 apartments of Affordable Housing.

Thursday, October 13, 2016

Announcing The Fröling Turbomat 500


The first Fröling Turbomat 500 (TM 500) has arrived in the USA! The TM 500 is a 1.7 mm Btu/hr. boiler capable of burning wood chips up to 45% moisture content or wood pellets. The boiler weighs over 18,000 pounds, in large part due to its heavily bricked firebox, which is necessary for wetter wood chips. The TM 500 uses a unique vertical heat exchanger that separates and drops out ash rather than allowing for ash to sit on horizontal heat exchanger surfaces. The TM 500 is designed to run 24 hours per day with no shutdowns for cleaning or re-fueling. The special alloy walking grate system needs no hoeing or scraping. The new TM 500 replaces another wood pellet boiler installed at Peoples Academy in 1982. The existing wood pellet boiler burned approximately 130 tons of wood pellets/year. The fuel feeding system is very simple for this installation. It consists of an exterior silo connected by flex auger to a surge bin above the boiler's feed auger.

The TM 500 will be replaced in the off shoulder seasons by a Fröling P4 100 pellet boiler when heat demand is lower. The P4 100 feeds itself by vacuum from the same silo that supplies the TM 500.

Both pellet boilers were sold and installed by Sunwood Biomass of Waitsfield, VT (802) 583-9300,

Below are some photos showing the assembly process.


The heat exchanger and the combustion chamber are joined together at the heat exchanger flange.


Neccessary components are installed before insulation and jacket assembly.


Insulation batts are installed.


Jacket frame assembled.


Boiler jacket panels installed.


Draft fan and stoker feed components assembled.


Flue gas recirculation, ash containers, door switches, air actuators, electical panel, etc installed.



Inside the combustion chamber (bottom). Here is good view of the moving grate and the fireclay bricks. Amazingly, all of this was asembled at the factory before it was shipped (approx. dimensions 3’x7’.


Combustion chamber (top).


The combustion chamber is almost large enough to lose someone.


Below, is a cross section view of the combustion chamber.

TM 500_Schnitt_2015-01-04 copy

A Fröling P4 80/100 boiler (350,000 Btu/hr) was also installed for use during the shoulder heating season. This TM 500 will be burning wood pellets. An intermediate surge bin (pellet hopper) was installed to bridge between the silo’s auger and the the boiler’s stoker fuel auger system.


The buffer tank and external fuel (wood pellets) silo.


Front view of Peoples Academy High School. The main building was built in 1928.


Friday, August 26, 2016

FireWood or Wood Pellets?

As one of the few companies in the United States that sells both firewood boilers and wood pellet boilers, we at Tarm Biomass face this question almost daily. Here is how we respond:

(Please take the survey at the end of the post)

Fuel availability and cost are often the first considerations.

Firewood availability:
If you own a woodlot with ample wood stocks then cutting your own firewood makes a great deal of sense.  When harvesting wood is part of managing the woodlot for forest health, firewood is a free byproduct.  We hear often from customers who have friends with wood or get wood from workplaces or other sources like community wood dumps for free.  Free or nearly free fuel is hard to beat even when labor is involved.  Firewood that is cut ,split, and delivered or delivered in log lengths is priced very differently in different regions.  Check your local classified advertisements to get a sense for firewood prices.  Many towns have electronic forums where information about local services is shared.  These electronic, public “bulletin boards” are a great way to learn about local firewood supplies.  Often even purchased firewood can cost 25-50% less than wood pellets by energy content.

Wood pellets availability:
Wood pellet mills  are located throughout the Northeast. Wood pellets are available in 40 pound bags almost everywhere.  20 pound bags are also available at some locations. Bulk delivered wood pellets are also available throughout most of the Northeast.  Production of bulk wood pellets is usually prioritized by mills over bagged fuel production.  Even when bagged fuel has experienced availability pressures, bulk fuel has been available. In the relatively densely settled Northeast, some regions remain over 100 miles from the nearest pellet mill, which makes deliveries expensive.  We recommend bulk fuel storage capable of storing a year’s usage of fuel remote locations.  For remote commercial locations, the ability to purchase entire truckloads of fuel is beneficial.  In other areas closer to pellet mills there are usually 1-3 delivery companies to choose from.  Bulk delivery companies in business today have been around a while and are reliable companies.  We suggest calling delivery companies to get a feel for their prices and service territories.  Custom delivery programs may be available.

What is involved with daily operation of a modern wood boiler?

Firewood daily use:
Today’s Froling gasification (two stage style) firewood boilers generally require twice per day batch loading and firing.  That is once about every 12 hours.  Lighting the fire takes less than 5 minutes due to the unique lighting door.  A typical home might use about 125 pounds or about 30 pieces of wood per day– a typical piece of firewood being about 18”-20” long with a 3”-6” cross section.  A medium size garden cart filled up will generally last 2 days in the coldest weather.  We find typical homes in the Northeast use 5-6 cords of hardwood firewood per year.  The wood must be less than 25% moisture content, under 20% is much better.  We recommend drying the wood in cut, split, stacked, and covered piles for two summers.  Having a wood shed or space to stack wood outdoors is essential.  Ideally the shed or stacking area is located in close proximity to the boiler. 

A small amount of ashes are generally removed once every week or two depending on how much wood is burned.  This process takes about 5 minutes. 

Wood pellet daily use:
Today’s Froling pellet boilers are nearly fully automatic.  Make sure your bulk fuel storage gets filled when needed and take the ash drawers out 3-5 times per year.  That’s it.  Owning a modern pellet boiler is like owning a modern oil or gas boiler.  It can operate for a month or more without intervention. 

How do wood boiler prices compare to pellet boiler prices?

Firewood boilers generally cost less than wood pellet boilers.  Wood pellet boilers have significantly more motors and moving parts for the automatic feeding and de-ashing functions.  However, the installed cost of wood boilers and wood pellet boilers is often similar.  All Froling wood boilers must be installed with thermal storage; 400 gallons minimum for the S3 Turbo 30 and 600 gallons minimum for the S3 Turbo 50.  Pellet boiler efficiency and operation can benefit from small volumes of thermal storage, but it is not a requirement.

How is fuel stored?

Firewood is ideally cut, split, stacked in rows, and covered for two summers.  Drying wood for one summer is OK, but significant fuel savings can be gained by allowing the sun and wind to dry the fuel for the 2nd summer. This is especially true for dense woods like oak and hickory.  Our typical customer burns 5-6 cords of wood per year.  A cord is a stack 18” wide x 6’ high x  14 1/2’ long.  If enough wood is on hand so that there is an extra summer of drying, a woodshed is ideal.  If building a woodshed with capacity for two years of wood, make sure it is constructed for pulling wood from alternating sides of the shed.  If a woodshed isn’t possible, try to find a sunny spot when there is air movement around the wood piles.  Avoid stacking under roof eaves, under heavy forest cover, or any shaded or wet spot.  Cover only the top of the pile.  Covering the sides traps moisture and gathers additional ground moisture.  If firewood is stored outside, it is a good idea to bring it into the boiler room for several hours before burning it.  Throwing chunks of 10° Fahrenheit or colder wood into a boiler is counter-productive for clean burning. 

Wood pellets:
Bulk wood pellets are delivered in 1+ ton quantities.  Typical residences use 6-8 tons of fuel and should be able to receive a 3 ton delivery without running out of fuel first.  This makes storage bins of 3.5-4 tons or more an ideal size.  Bulk delivered wood pellets are often stored in basements or utility rooms adjacent to the boiler.  Custom built wooden bins or pre-fabricated wood-reinforced cloth bins are typical storage options.  Pellets must remain dry, but humidity isn’t normally a problem.  Commercial sites often take deliveries in 10 ton increments.  Outdoor storage of wood pellets is best accomplished in agricultural silos.  Whatever the bin, a slide gate at the base of the bin is a must to allow maintenance without having to dump all of the stored pellets.  Sometimes dust can accumulate in the bases of silos and bins causing flow blockage.  This area infrequently requires maintenance, but when maintenance is required, a slide gate makes the work easier.  Most Tarm Biomass customers use bulk delivered fuel.  Bagged fuel is another option.  Though not as convenient, bagged fuel may be more cost effective.  Ideally bagged pellets are stored under cover even when packaged in plastic. 

What’s your philosophy?

For some, burning wood is life-long hobby.  Putting up the firewood is as en-grained in their lifestyle as mowing the lawn or planting a garden.  For those people there is great satisfaction from being in charge of next season’s heat.  When the wood pile is stacked for the season, there is a tremendous sense of accomplishment and independence.  There is no relying on a wood pellet infrastructure to supply fuel, or worse the regime of a hostile petro-state.  Cutting, splitting, and stacking firewood is a great form of exercise and is a great reason to spend time in the woods.  For some, stacking wood is meditative.

There is a generation of firewood burners who have burned wood for a lifetime and now their bodies can no longer perform the task.  Having sold wood boilers since the 1970s, we get calls at Tarm Biomass regularly from those folks.  There is no shame in switching to wood pellets when the body can no longer handle the wood.  It is a hard switch, but rest assured, wood pellets are still a local fuel and often primarily made from wood waste. 

For others, firewood is a dreaded task.  Time for many families is in short supply.  Some would like to spend free time with other hobbies.  The ability to push a button and burn locally grown wood in pelletized form is the ultimate form of heating satisfaction.  With almost complete automation, Froling P4 automatic pellet boilers heat quietly and according to calls from the thermostat or domestic hot water tank.  Making wood heat forgettable can be very attractive.

Which would you choose? 

Which would you choose?