Air Quality of Outdoor Wood-Fired Boilers

By Todd Fratzel on Air Conditioning

Outdoor Wood-Fired Boilers

Outdoor Wood-Fired BoilerOutdoor wood-fired boilers have become extremely popular around here in the last few years. Last year when oil hit record prices I started seeing these outdoor units pop up everywhere I drove. Unfortunately they haven’t been completely welcomed by annoyed abutters and neighbors.

The problem with these outdoor boilers is SMOKE! First of all they typically have a very short smoke stack on them which doesn’t do a great job getting the smoke up and away from surround structures. Secondly these units create more smoke than normal because of house the firebox is constructed. The firebox is completely surrounded with a water jacket, hence being a boiler. It’s a very effective way to transfer the heat to the water which in turn heats your home. However, it makes it very difficult if not impossible for complete combustion, hence the nasty smoke. Complete combustion of wood occurs at temperatures above 1000 degrees F, however, the surface of the firebox can’t get that hot when it has 150 degree water on the other side.

Setbacks, Stack Heights and Combustion

Recently the State of New Hampshire passed laws governing the placement and use of outdoor wood-fired boilers. You can read more about recent changes to the NH laws with this outdoor wood-fired boiler fact sheet. The following are the new requirements in New Hampshire.

Setbacks & Stack Height

  • Phase I units: Must be 100 feet from nearest property line; stack height must be two feet higher than the peak of a roof of a residence or business not served by the unit, which is located within 300 feet.
  • Phase II units: Must be 50 feet from the nearest property line; no stack height requirements.
  • Non-Phase I or II units: Must be 200 feet from nearest property line; stack height must be two feet higher than the peak of a residence or business not served by the unit, which is located within 300 feet.

Combustion Requirements

  • Phase I emissions levels of 0.60 pounds of particulate matter per million British thermal units (Btus) of heat input
  • Phase II emissions levels of 0.32 lbs. of particle pollution per million Btus of heat output.

Be A Good Neighbor

Ultimately the new laws have been implemented to try and protect the health and value of neihboring properties. However, even with these new requirements it’s very likely that outdoor wood boilers will cause strife between neighbors. If you’re thinking about installing one of these energy effecient boilers then I highly recommend you discuss it with your neighbors. Taking a proactive stance with such a significant decision you’re likely to earn some respect from your neighbors and prevent some expensive legal battles.

Do you have an outdoor boiler or a neighbor with one? What are your thoughts?

About the author

Todd Fratzel

I'm full time builder for a large construction company in New Hampshire. I run their design-build division that specializes in custom homes, commercial design-build projects and sub-divisions. I'm also a licensed civil and structural engineer with extensive experience in civil and structural design and home construction. My hope is that I can share my experience in the home construction, home improvement and home renovation profession with other builders and home owners. I'm also the Editor-in-Chief and Founder of Tool Box Buzz. Please feel free to contact me if you have any questions, suggestions or you'd like to inquire about advertising on this site.

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