Facts About Outdoor Wood Burning Boilers

Need to heat your home in the country as inexpensively as possible? You may want to consider an outdoor wood boiler. The boiler is a relatively new technology for home heating and offers an alternative to burning wood indoors in a wood burning stove.

The outdoor wood boiler is known by several different names - such as an outdoor wood burner, an OWB, and an outdoor wood hydronic heater or OWHH. The OWB consists of of a firebox housed in a steel-sided enclosure, with a roof and can be about 10 times the size of an indoor wood burning stove. The outdoor wood burners are popular in rural areas of the United States.

How does it work?

The OWB works by heating water in a large stove outside the home and then transferring the heated water through underground pipes. When the water reaches the home, a heat exchange transfers the heat to an existing indoor furnace - which will then circulate the heat throughout the house.

What about safety?

By using the furnace outdoors, the safety issues associated with an indoor wood stove are eliminated including:

- the elimination of a chimney or flue fire

- the elimination of the possibility of carbon monoxide buildup inside the home along with harmful fumes

- the elimination of the chance of a gas explosion.

Since 2007, some newer model OWBs were introduced with improved design in combustion that also pass the new voluntary EPA (Environmental Protection Agency) regulations.

What about the cost of operating?

Wood is still considered a renewable resource that is plentiful (but know the source to be sure), and is usually inexpensive. In some cases it can be free if you provide it from your land.

Using the outdoor wood boiler will help eliminate or reduce electric, gas or oil heating bills. Your home will be less drafty because there is no indoor combustion appliance to draw in cold outdoor air to replace air used for combustion.

Can it heat my barn also?

Yes, the boiler can heat more than one building along with your home. It can heat the barn, garage, greenhouse, hot tubs, and the swimming pool. The firebox is about ten times that of a traditional wood stove, allowing for more wood. Also by using larger round timber, it is cheaper than smaller short split wood. For example, large round timber costs between $80 to $90 a cord while, smaller split wood costs between $120 to $140.

What about insurance?

The outside wood boiler is not pressurized like your conventional boiler because it is outside and open to the atmosphere. Therefore, this type of outdoor boiler is not subject to the same regulations that apply to a pressurized heating systems. Since they are located away from the home, they will not affect the insurance rates of the homeowner.

How clean?

Indoor air quality is not affected - reducing the risk of respiratory problems.

All the dirt of a indoor wood burning stove now remains outdoors. All the ashes, and the creosote - which causes sooty walls and ceiling. And keeping the logs outdoors keeps out the bugs.

It can't be so perfect, can it?

There are rules and regulations to consider before you think of investing. Improper burning techniques have been the cause of pollution, resulting in complaints. States and localities have responded by regulating or banning the furnaces entirely. Before buying a furnace check with local regulations.

The EPA has certified emissions since 1990 for indoor wood stoves, but only recently has the testing and certification begun for OWBs, according to the Vermont Department of Environmental Conservation. The regulations specify furnaces that are Phase l, Phase ll and meet specific air pollution controls, or are simply wood burning furnaces.

Can you spell out the Vermont regulations?

In Vermont the regulations are as follows:

After March 31, 2010 the only type of outdoor wood burners (OWB) that can be purchased must be the new Phase ll OWB - which has been certified by the Vermont Air Pollution Control Officer and can meet particulate matter emission limits.

After October 1, 1997, a furnace that is not a Phase l or Phase ll must be installed more than 200 feet from a residence if the furnace does not serve that residence and does not belong to the owner of that residence. Also the permanent stack on the furnace must also extend higher than the peak of the roof of the residence being served - the regulation also applies to Phase l furnaces. However, if it is a Phase ll furnace, the regulation requires instead, a 100 foot distance from the residence. And all applicable local laws, regulations, and ordinances apply.

Also required is the use of allowable fuels: untreated natural wood, pellets made from untreated wood, home heating fuel that complies with sulfur content limits in the case of duel-fired furnaces, as well as other biomass fuels that have been certified for Phase ll furnaces. Additionally, the furnace must be installed in accordance to the applicable Vermont requirements, while taking into consideration all local laws, regulations and ordinances.

After March 31, 2010, only Phase ll outdoor furnaces can be sold. A manufacturer must now have certification issued by the Air Pollution Control Officer (APCO), proving that the furnace is a Phase ll OWB. Certification is vaid for five years from the issuance date unless revoked by the APCO. To receive this certification the manufacturer must demonstrate that emissions limits do not exceed the permissible amount of particulate matter based on which fuel is used.

Emission testing will be done by independent testing consultants. If the furnace does not comply with the emssions limits and testing criteria as specified, it will be revoked by Air Pollution Control Officer.

What if I don't live in Vermont?

Your state may not permit the OWB. However, Vermont regulations may set the future standards so you may want to be aware of what they are.

Should I invest?

I think it may be worthwhile if someone has a lot of land and can replenish what falls down - or they chop down. And if they have more than just a house to keep warm, like a barn and a greenhouse. If you have a local source for the wood, that too can make sense. I like the idea of burning wood over using oil, and I do not like gas at all in or near the house.

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