Wood boilers becoming heated debate in Salisbury
January 15, 2007
By JOHN FLOWERS
SALISBURY — Outdoor wood-fueled boilers (OWBs) have suddenly become an incendiary topic in the town of Salisbury, where the planning commission has proposed a temporary ban on the smoke-producing heating devices.
The suggested moratorium
one in a series of draft interim zoning regulations now being reviewed by town selectmen — is being praised by some residents as a means of promoting better air quality in town, but is being panned by other citizens who argue they should be able to install whatever heating units they want on their own property.
Salisbury selectmen hosted an informational meeting on the subject on Jan. 10, a gathering attended by around 40 people, including two air quality experts from the Vermont Department of Environmental Conservation (DEC).
“Some people were concerned; no one said let’s shut (OWBs) down,” Salisbury Selectman John Beattie said of public feedback at the meeting.
OWBs have become a more popular home heating source in recent years as the cost of fuel oil has risen. They are located outside of the home, business or greenhouse they are heating. They typically possess a large firebox that is surrounded by a jacket filled with water. Burning wood within the firebox heats the water, which is then circulated into the homes through underground pipes.
Unfortunately, outdoor wood boilers have a tendency to smoke — profusely, at times. And it is not just in Salisbury that public officials are taking notice; the state is also considering greater regulation of the devices.
Phil Etter, an environmental analyst with the DEC who attended the Jan. 10 gathering in Salisbury, explained that most OWBs employ very primitive combustion technology. He said when the water I circulating through the furnace reaches a preset upper limit — usually around 180 degrees Fahrenheit — the air supply to the fire is cut off, cooling the fire so the water won’t overheat. The furnace operates in this “idle” mode until the water temperature hits a lower set-point and the air supply is re-established.
Etter noted the lower burning temperature, coupled with the substantial amounts of unseasoned or wet wood some people stoke into their boilers, can create dense plumes of smoke.
“They are generally cold fires, so there is inefficient combustion,” Etter said. “You have a lot of wood smoldering away.”
It’s a dense smoke that, in many cases, gets discharged from short stacks. As such, the smoke can hug the ground as it wafts into neighboring yards and homes.
“They are easy to operate poorly,” Etter said of OWBs.
It was in 1997 that the state adopted rules that placed some restrictions on where people could situate OWBs on their property. Those rules prohibit OWBs from being installed within 200 feet from someone else’s residence. The rules also state that if an OWB is within 500 feet of another residence, the stack of that OWB must be higher than the roof of the structure the boiler is heating.
A new rule on the DEC’s drawing board would establish, for the first time, some emissions standards for OWBs. That rule would prohibit retailers from selling OWBs in Vermont that do not meet a “particulate matter emission limit of 0.2 grains per dry standard cubic foot of exhaust gas corrected for 12 percent CO2 for newly manufactured outdoor wood-fired boilers.”
“It would require manufacturers to improve combustion technology to pass emissions standards,” Etter said.
He noted that communities in other states — such as Massachusetts and New York — have already passed laws regulating OWBs. Maine, he said, is also dealing with the issue.
Some manufacturers already make OWBs that would conform to the proposed Vermont standards, according to Etter.
“We don’t want to be going backwards, in terms of air quality,” Etter said.
Salisbury officials concede there are only a handful of OWBs in town right now. Still, the planning commission thought it would be a good idea to draft some rules to prepare for a future when the boilers — and associated complaints — may become more numerous.
“We thought of it as a health situation that concerned the whole town,” said commission member Martha Sullivan.
Beattie said an OWB moratorium could be justified in certain neighborhoods in Salisbury. But he believes that an ideal outcome would be for the state to pass rules governing the boilers rather than individual towns passing their own regulations. And Beattie stressed he does not want to see residents denied the chance to own OWBs; rather, he would like to see manufacturers and retailers deliver products that are more environmentally sensitive and that would not create health hazards for surrounding neighbors.
“I recognize the industry will only produce safe and efficient OWBs when there is pressure from the state and individuals that are interested in seeing that happen,” Beattie said.
Selectmen will decide within the next few weeks whether to adopt the planning commission’s interim zoning regulations. The board could also reject some or all of the regulations, or send them back to the commission for reworking.