Can emissions from outdoor boilers be controlled?

Yes!

Outdoor boilers have become popular in rural areas and small towns all over Canada. Their users like the fact that the 'mess' of wood heating is kept outside and that the boiler can also provide domestic hot water. Prospective purchasers are also told by most outdoor boiler (OB) suppliers that their products are safer because indoor wood heating equipment is inherently hazardous.

Because of high smoke emissions, these units have become the focus of anger and frustration among the neighbours of OB users, and are the subject of an increasing number of complaints to municipal and provincial governments. It is clear that governments have neither the mechanisms nor staff to follow-up on these complaints or to mediate solutions. Dozens of municipalities have enacted bylaws designed to minimize the impact of OBs on non-users. These include their prohibition from properties zoned residential, minimum set backs from property lines and minimum stack heights. Given the spectacular plumes of smoke from OBs firing after off cycles, even these bylaws may not protect neighbours from the choking smoke and odors.

But it is not just the neighbours who are annoyed about OBs – owners have had costly disappointments too. Leaks resulting from thermal stress and corrosion have spilled poisonous antifreeze into yards, creating huge clean-up costs. Small, regional OB manufacturers, lacking adequate heating industry experience and resources for proper R&D on their products, have been overwhelmed by warranty claims and disappeared, leaving owners with expensive, unusable junk in their yards. Users have been shocked at their OB's appetite for wood, and the smoke produced from their boilers has caused some owners to discontinue their use.

Manufacturers of OBs with crude or nonexistent combustion systems have effectively downloaded a costly problem on the neighbours of users and their local governments. Some OB manufacturers actually blame the smoke on incompetent users, who burn large chunks of wet firewood. Improper use is certainly part of the problem, but we have heard from responsible users who have tried everything to reduce the smoke output from their OBs with only limited success.

Clearly, OBs are a problem.

On the other hand this is a product category that rural Canadians have embraced enthusiastically. Farmers use OBs to heat their houses and barns. Hundreds of rural businesses operated on the same properties as the owners' houses – shops, garages, studios and so on – benefit from the economies of mini-district heating. OBs have become an important and necessary product for rural Canadians. So important, in fact, that they need to be improved to make them more effective and acceptable environmentally.

Smoke emissions from OBs can be reduced

One thing needs to be made clear:  Smoke emissions from OBs can be reduced. There is no question that developing competent combustion systems is an engineering challenge for most OB manufacturers because until now they have given the problem so little attention. But a well-worn path already exists. There are proven combustion systems that are capable of meeting the EPA/B415 emission limits. The challenge is to adapt them to the scale of OBs and to select materials that can tolerate the stresses involved.

The development work will be costly and there will be frustrations and failures along the way. The challenge facing OB manufacturers today is similar to that faced by wood stove manufacturers fifteen years ago. The main difference is that the wood stove manufacturers really were breaking new ground since no proof existed that their quest for a clean burn would pay off. Now we know of at least four quite different combustion designs that have been successfully used to control emissions from wood burners.

Now is the time to deal with OB emissions. Once the challenge has been met, the successful manufacturers can look forward to a strong demand for, and much less criticism of, their products. And rural Canadians will have access to good products in this important category, and will be able to use them without guilt or apology.

JG