Tarm Solo Plus 30 Wood Boiler  The Tarm Solo Plus 30 Wood Boiler.

Important Wood Facts

  • Every Cord of wood you burn in a high efficiency wood boiler from reVision heat eliminates 150 gallons of oil.
  • Cord Wood, delivered at $200 a cord, is the equivalent of $1.75 a gallon oil.
  • A wood boiler, without thermal storage, can eliminate 75% of your energy bill when run from November through March.
Adobe PDF Download a Brochure for the Tarm Solo Plus (PDF) Manufacturer website: http://www.woodboilers.com/

Wood Boilers

High efficiency, well built wood boilers installed by ReVision Heat represent one fantastic route off of oil for many of our clients. With this one decision, you can cut the cord to Middle Eastern oil and connect your energy demand to the woods around you.

All of the boilers that we sell are gasifying wood boilers, which burn at 80 to 85% efficiency through a process called ‘wood gasification.’ These wood and pellet gasifying boilers emit no visible smoke because the combustion temperatures reach 1800+ degrees Fahrenheit.

Smoky outdoor wood boilers, on the other hand, burn at 50-60% efficiency, and are coming under state restrictions due to their polluting emissions. It is also worth noting that typical older model wood stoves burn wood at between 50-60% efficiency, requiring much more wood to produce the equivalent BTUs from a wood boiler.

Here is a Video from the Manufacturer Demonstrating How Easy it Is to Start the Solo Plus Wood Boiler:

Why We Use Tarm Wood Boilers

For over 70 years, Denmark-based Tarm has been the world leader of solid fuel technology. When fed dry wood, these boilers burn at 85% efficiency; they not only burn much less wood than conventional wood boilers and wood stoves, but burn so clean that there is virtually no risk of a chimney fire. During an average winter day in Maine, these boilers generally would be fired only a few times a day, depending on the efficiency of the building and amount of heat storage.

Thermal Storage

The biggest decision to make regarding wood boilers is if you’re going to start with thermal storage or not.   Thermal storage simply means have a tank to store the excess heat generated by your clean-burning gasifying wood boiler.

The beauty of thermal storage is that it makes heating with wood as easy as one 5-minute trip to the boiler each day to kindle one fire. A large thermal storage tank allows the wood boiler to run at maximum combustion temperature, and highest efficiency, because the large amount of heat energy generated can be discharged into the storage tank. The heat stored in the tank is then siphoned off over time to heat your house and domestic hot water.

Another option is to discharge the heat into a concrete slab. Much like water storage, concrete storage allows you to burn at the highest possible efficiency and then gradually use the heat energy as needed, over time. ReVision Heat’s custom-built thermal storage tanks are the result of years of research and development to come up with a design that offers maximum durability and excellent insulation to store the precious BTUs generated by your wood or pellet boiler.

However, the addition of thermal storage increases the cost of a wood boiler system.

Wood Boilers Without Thermal Storage

For wood boilers without thermal storage, we will typically install what is called a double injection system. In these systems, either the wood boiler or the backup boiler is injecting heat into the distribution system. When the wood boiler is cold, the oil or gas boiler takes over.

See the example  below:

Wood Boiler Schematic


Wood boilers require a dedicated flue. A wood stove may be on the same flue, but it may interefer with the draft. Flues need to be clay tile lined at a minimum. If there is no lining, chimney’s can be pre-fabricated metal.

Wood Requirements

You can offset 75% of your energy needs offsetting 150 gallons of fuel oil with every cord of firewood you burn. Wood needs to be well seasoned. We find that wood that is split stacked and under cover by Spring of the year is ready to burn by the fall of the same year. Wet wood does not gasify. Larger Compressed wood products work well in gasifing wood boilers as well.

Space Requirements

Most of our wood boilers live in the basement, where they require a little more space than the oil boiler that sits next to them. It is possible for the wood boiler to live in a garage, but a garage cannot have a door that leads from the wood boiler directly to a space that can have a car parked in it. This means that if the wood boiler is to live in the garage, a new room needs to be created with a door opening to the house or to the outside. The wood boiler must be frost protected. Some of our clients build sheds that also store wood and pipe heat to the house from the boiler.

Thermal Storage Systems

Wood Boiler thermal storage tankA 650 gallon thermal storage tank, below an installed Boiler

Burning wood can be made more convenient and more efficient through the use of a thermal storage system. These are large, 600 to 1100 gallon, super insulated tanks that have copper heat exchange coils in them.

When the wood boiler is fired, all of the heat from the boiler goes into storage. This allows for more convenient firing (once or twice a day in the coldest part of winter, down to once a week in the summer months). There is no better way to heat a house than a wood boiler with storage! It is, by far, the most efficient, most convienient way to go.

We build a very rugged thermal storage tank and sell it as a kit for homeowner assembly, or as a fully installed system. The only reason not to install thermal storage is cost. Installing a thermal storage system adds between $5,000 and $9,000 to the cost of a system, depending on the size, complexity and labor involved.
Wood Boiler System Schematic with Thermal Storage

General Requirements for Boilers with Thermal Storage


Wood boilers require a dedicated flue. A wood stove may be on the same flue, but it may interefer with the draft. Flues need to be clay tile lined at a minimum. If there is no lining, chimney’s can be pre-fabricated metal.

Wood Requirements

You can offset 100% of the fossil fuel you burn with 1 cord for every 150 gallons of oil. Wood needs to be dry.

Space Requirements

The same issues for locating the boiler apply to systems with thermal storage; the boiler can be inside the basement adacent to a chimeny, or in a garage if it meets fire code, or outside. The thermal storage tank wants to be inside, however.

There are a lot of issues to work through for systems to meet your needs. Boilers and thermal storage sytems need to be properly sized. Let the crew at ReVision Heat provide a free home heating consultation and prepare a system design for you!