The Clean Warmth of an Engineered, Regulated Fire

The fact that the U.S. EPA finalized the first new source performance standards (NSPS) for residential wood heaters since 1988 won’t have much bearing on some wood and most pellet stoves on the market, today or five years from now when emissions standards tighten. For other products, such as forced-air wood heaters, single burn-rate wood stoves and even pellets themselves, the new regulations could be a game-changer.

What makes these source performance standards unique is that they regulate consumer products. John Crouch, director of public affairs for the Hearth, Patio & Barbecue Association, says NSPS are typically issued to regulate industry, such as refineries and power plants.

The new standards were finalized in February and reflect significantly improved technology now available to make a range of models cleaner burning and more efficient. The rule sets the first-ever federal standards for hydronic heaters, wood-fired forced-air furnaces, pellet stoves and the previously exempt single burn-rate stove.

The EPA states that this new rule will result in emissions from new models being reduced by approximately two-thirds, which is estimated to provide $3.4 billion to $7.6 billion in public health benefits. Those who purchase the new stove models will also benefit from efficiency improvements, which means they will need less wood to heat their homes. EPA also estimates the rule will reduce fine particle and volatile organic compound emissions from heaters covered by the rule by nearly 70 percent, with carbon monoxide emissions reduced by 62 percent.

“One of the things that makes this rule very complicated is that it involves four very different products,” Crouch tells Pellet Mill Magazine, “only one of which (wood stoves) was in the original NSPS.”

Wood And Pellet Stoves
EPA estimates that about 88,000 pellet stoves, 86,000 adjustable burn-rate wood stoves, and 27,000 single burn-rate wood stoves will be sold this year alone. The new standards for wood and pellet stoves have two steps, with the first set of requirements taking effect 60 days after the final rule is published in the Federal Register and the second limit taking effect in 2020. The step-one emissions limits for new wood and pellet stoves is 4.5 grams of particulate matter (PM) per hour of operation for catalytic and noncatalytic stoves. The step-two PM limit is 2 grams per hour for catalytic and noncatalytic stoves if emissions are tested using cribs (lumber assembled in standardized configurations) or 2.5 grams per hour if tested with cordwood (split logs) using an EPA-approved method.

“The de facto national standard for stoves was already 4.5 grams an hour, since Washington state made that their standard in 1995,” says John Ackerly, president of the Alliance for Green Heat. “Very few stoves were on the market that put out more than 4.5 grams per hour of particulate matter, so the wood stove market is barely impacted.” And even though all pellet stoves put out less than 4.5 grams per hour already, they have to be certified now, Ackerly says, so they have to go through the process. “Some may be redesigned but most will be the same as what has been on the market,” he tells Pellet Mill Magazine.

Kelsey Scheel, public relations manager for Hearth & Home Technologies, a major manufacturer of wood and pellet stoves under the Harman brand name, says HHT agrees with the step-one emissions limits of 4.5 grams per hour. “In fact, our products already comply with it,” she says. This year Harman is launching the Absolute43 with “EASY Touch Controls” that will, according to Scheel, redefine how consumers interact with a pellet stove. Its unique features include automatic maintenance reminders of when and how to clean the stove, reminders to fill the hopper, on-board diagnostics and a scheduling feature that helps save fuel.

Paul Williams, national sales manager for United States Stove Co., offered this statement to Pellet Mill Magazine instead of addressing our inquiries about the NSPS. “As everyone I’m sure is doing, we’re going through the prepublication and making adjustments,” Williams says. “Very little is much of a surprise, as we’ve been working through the process since the beginning. But there is always something that draws a questioning look and until the final version is released, we have to hold.”

Crouch confirms that most pellet and adjustable burn-rate wood stoves already meet the 4.5 grams per-hour limit, adding that the first NSPS’s definition of wood stoves hinged on an air-to-fuel ratio to keep fireplaces out. The new NSPS also does not cover fireplaces, fire pits, pizza ovens, barbecues or chimineas, which are earthenware outdoor fireplaces shaped like a light bulb with the bulbous end housing the fire.

“The intention [of the NSPS] was that it was supposed to cover all residential wood heaters,” Ackerly says. “Some at EPA even wanted to include fireplaces, and many stakeholders urged the agency to include them.”

Ackerly says adjustable burn-rate wood stoves make up 90 percent of the wood stove market. “All EPA-certified stoves and almost all older, uncertified stoves allowed the operator to adjust the rate of air that goes into the firebox,” Ackerly says. “Adjusting the airflow also adjusts the heat output. The more air, the hotter the stove. The less air, the cooler. The EPA designated single burn-rate stoves as exempt from regulation in 1988, when they did the first NSPS for residential wood heaters. They have a set rate of airflow, which has to be very high to be exempted from EPA emissions regulations.”

To ease the transition to cleaner stoves, EPA’s final rule will allow wood stove retailers to sell existing inventory until Dec. 31. After that date, any new wood stoves sold at retail in the U.S. must meet the step-one emissions limit. Ackerly says the sell-off period is mostly for the exempt, single rate-burn stoves, and for boilers and furnaces. “The technologies that are being regulated out of existence are the most impacted—like the single rate-burn stove,” he says.

Crouch says there are at least two or three types of catalytic wood stoves available today, but noncatalytic stoves dominate the market. Noncatalytic stoves use more sophisticated air mixing, employing three or four different entrances where air fuels the fire. “Much of the differences are opaque to the consumer, shifting from primary to secondary and so forth,” Crouch says. Smoke contains a lot of energy, and many clean-burning wood stoves on the market today barely emit any visible smoke. The newer models also burn up to 50 percent less wood than the older, less sophisticated models for the same heat output, Crouch points out. Harman wood stoves and inserts currently use its noncatalytic FireDome and FireDome Plus Combustions System, “and we are working on a unique, new wood stove technology that we’ll introduce in the coming years,” Scheel tells Pellet Mill Magazine. Currently, Harman does not offer catalytic wood stoves or fireplace inserts.

As a result of the new NSPS, catalytic wood stoves may become the fastest growing model in that category, Ackerly says, because most manufacturers are considering adding catalysts in order to meet the 2 gram per-hour standard. “Pellet stoves have been a fast-growing category, and the new regulations won’t slow this down—or speed it up—since pellet stoves aren’t that affected by the NSPS,” he says.

Some noncatalytic wood stoves already achieve less than 2 grams per hour of PM, so hitting the 2020 limits is “not only possible, but also regularly done by manufacturers,” Ackerly says. “It involves a lot of fine-tuning and injecting air in all the right places, and really maximizing your secondary and often tertiary combustion.” He says he doesn’t expect to see many new downdraft stoves, “but that is a unique way to achieve secondary combustion. It is often very finicky and relies on a skilled operator.” As with noncatalytic designs, there is a lot of variety among catalytic designs, Ackerly says. “One option may be to preheat the cat in order to achieve secondary combustion in the catalyst sooner. Automation, using sensors and automatic adjustments of airflow, may also become an attractive way to reduce emissions without driving up the price too much.”

Hydronic And Forced-Air Wood Heaters
Hydronic heaters are typically located outside the buildings they heat in small sheds with short smokestacks. They burn wood to heat liquid, either water or a water-antifreeze mixture, which is piped to provide heat and hot water to occupied buildings such as homes, barns and greenhouses. Hydronic heaters may be located indoors and they may use other biomass as fuel, such as corn or wood pellets.

Like the wood and pellet stove standards, the new regulations for hydronic heaters will be implemented in two phases, with the first set of requirements taking effect 60 days after the final rule is published in the Federal Register and the second limit taking effect in 2020. The step-one PM limit for hydronic heaters is 0.32 pounds per-million Btu heat output (weighted average) with a cap of 18 grams per hour for individual test runs. The step-two limit is 0.1 pounds per-million Btu heat output for each burn rate if testing with crib wood. If testing with cordwood using an EPA-approved method, the step-two limit is 0.15 pounds per-million Btu heat output for each burn rate. “The achievability of these standards will rest significantly on the test methods for hydronic heaters, for which manufacturers have many unanswered questions,” says Joseph Seymour, executive director of the Biomass Thermal Energy Council.

For wood-fired forced-air furnaces, the final rule requires wood-practice standards beginning on the effective date of the rule, with emissions limits phased in over two steps between 2016-‘17 and 2020, to give manufacturers time to develop cleaner models and conduct emissions testing. Small forced-air furnaces will have to meet step-one emissions limits by 2016. Large forced-air furnaces will have an extra year to meet step-one requirements, with compliance required in 2017. All forced-air furnaces are required to meet the step-two emissions limit by 2020. The step-one operational- or work-practice standards take place 60 days after the final rule takes effect. The step-one limit is 0.93 pounds of PM per-million Btu output, weighted-average, and cordwood testing is required for forced-air furnaces. For small furnaces, the step-one requirements go into effect in 2016, for large furnaces, they go into effect in 2017. The step-two emissions limit of 0.15 pounds of PM per-million Btu heat output for each individual burn rate takes effect in 2020 and also requires cordwood testing.

Delaying implementation of limits on forced-air furnaces is either a good decision or a bad one, depending on who is asked. Ackerly says this was a mistake. “Wood and pellet boilers had a voluntary program where EPA established a test method and standards, and companies could get their boilers qualified,” he says. “No such program existed with warm air furnaces so the EPA did not have test methods or data to know where standards should be set. We think it was a mistake to give them so much more time. The EPA should have at least had them meet some interim test in order to know who was working toward cleaner furnaces, and who had no intention of meeting any standards but just wanted to keep selling dirty equipment for two more years.”

Crouch, however, thinks otherwise. “Of the step-one process, the agency did the proper thing with hydronic heaters,” he says. “We’re thankful EPA gave warm-air furnaces more time. They never had any certification, and they’re so different. They need every minute they can get.”

Several changes were made between the proposed rule and the final rule. In addition to changes made regarding masonry heaters and the implementation timeline for forced-air furnaces, the final rule changes the step-one emissions cap for hydronic heaters. The cap now matches the current requirements of the agency’s voluntary Hydronic Heaters Program. The change allows most models that are phase-two qualified under the voluntary program to be automatically certified as meeting the first emissions limit in the final rule.

To reduce potential certification delays, the EPA said it will allow conditional certification for up to one year for wood stoves, pellet stoves and forced-air furnaces if a manufacturer submits a complete certification application that includes a full emissions report by an EPA-accredited laboratory and meets other application requirements.

“We are pleased with many of the step-two rulings,” Scheel says, “such as the EPA’s recognition of industry concern about the length of time for the certification process. Under the current rules, it can take up to 90 days to get a certificate granted before a manufacturer can begin producing and selling a wood stove, but under the final rule, there will be a temporary certification process that allows manufacturers to begin production as soon as the certified third-party lab verifies that emissions meet the requirement and the application is submitted to the EPA.”

Testing: Crib Vs Cord
While EPA will not require emissions from wood stoves and hydronic heaters to be tested with cordwood rather than the crib wood, the agency will allow cordwood testing for wood stoves and hydronic heaters with prior approval. To encourage further development of cordwood test methods, the EPA is including a slightly higher step-two emissions limit based on cordwood testing for wood stoves and hydronic heaters. Based on available data, the EPA said it anticipates the alternative limit would be at least as stringent as the emissions limit for crib testing. The EPA also indicated manufacturers can test using either cribs or cordwood in step two, and must meet the limit corresponding to the type of test they choose. However, manufacturers that test with cordwood for step one must meet the same emissions limit as those testing using cribs. In addition, any manufacturer choosing to test wood stoves or hydronic heaters with cordwood will be allowed to voluntarily use a special EPA label that recognizes emissions from cordwood testing more closely reflect emissions from in-home use.

The step-two, 2-gram limit for pellet stoves and 2.5-gram limit for cordwood testing are “arbitrary numbers plucked out of thin air,” Crouch says, adding that a cordwood test method isn’t even finished yet, so how can EPA pick a number—2.5 grams—if a finalized test method for cordwood isn’t even completed? He also says that once a cordwood test method is approved, it may be problematic not only for third-party reproducibility of results, but also in-house test results consistency.

The allowance for voluntary testing with cordwood using an alternative test method approved by the EPA “may become one of the most sensitive and disputed sections of the entire NSPS,” Ackerly says, “as it may allow the EPA to gather enough data showing acceptable test methods that can achieve low-emission rates with cordwood. I expect in the next two years we will see a number of stoves being tested and certified with cordwood and some will even be under 2 grams per hour. The EPA will allow those units to carry a special hangtag so that consumers can more easily identify which stoves are being designed and tested to run the same way that the operator will.”

Scheel says HHT was “a little surprised” by a few of the guidelines under step two. “For example, we appreciate the option of two methods for compliance—the first uses the current crib wood test methodology at a limit of 2 grams per hour,” she says. “This is lower than what a recent study showed the precision level to be, but is likely based on historical emissions data from a consensus-based test method. The second option uses a cordwood measure, which we agree is where these guidelines need to move in the future. However, we take issue with the EPA proposing an option that does not have a finalized consensus-based test method or a known completion date.” HHT’s position on the 2.5-gram limit mirrors Crouch’s sentiments. “We don’t understand the logic in setting an emissions limit at 2.5 grams per hour without this test method in place to develop statistically viable data,” Scheel says. “While the EPA believes this option will drive manufacturers to take up the cordwood option, which is what we all want, it may have the opposite effect. Until an approved and finalized test method is completed, it will be difficult for manufacturers to devote resources to developing a stove to meet the cordwood emissions requirement—and beyond that, we have no way of knowing whether the 2.5 gram-per-hour limit is reasonable since it was set without reliable data.”

Ackerly says in the previous NSPS and the new one, stoves are tested at four burn rates and then those four numbers are averaged. “So at the low-burn rate, a stove could emit 10 grams an hour, but if it does well enough at the high-burn rates, it can be certified,” he says. The proposed NSPS said that stoves had to be under 4.5 for all burn rates. “The idea was good, but the implementation was problematic,” Ackerly says. Scheel agrees. “It’s a positive step that the EPA abandoned the proposed high-and low-burn rate average with a cap,” she says, “and instead went back to the weighted average of all four burn rates, as this is a more accurate representation of consumer usage.” Ackerly also says that poor operation is widespread, however, which undermines advances that many new certified stoves technologies offer. “Ultimately, we believe that some types of automation are needed to prevent the widespread consumer misuse of wood stoves,” he says. “The attempt by the EPA to set a maximum-emission level while the stove is on its lowest burn rate was a good start. We had urged the EPA to more formally address alternative tests for automated stoves that hold tremendous promise to reduce widespread poor operation by consumers.”

Pellet Fuel Standards
The NSPS rule requires any new noncommercial wood-burning appliances to utilize fuel that has been graded as part of a licensing agreement with an EPA-approved organization, such as the Pellet Fuels Institute. For appliances such as pellet stoves, manufacturers will be required to state such claims in the owner’s manuals. Rather than designating one fuel standards program for the industry, the NSPS rule as written allows pellet manufacturers to choose among three programs, including the PFI Standards Program. The other two pellet standards programs are CANplus and ENplus.

“PFI has significant concerns that the current EPA language—allowing for U.S. pellet producers to choose among multiple standards programs—will cause more confusion than clarity among manufacturers, retailers and consumers as they try to grasp what the different programs and fuel standards mean,” says Jennifer Hedrick, PFI executive director. “We are surprised that EPA did not choose the PFI Standards Program as the sole program for U.S. pellet manufacturers, despite the fact that the Pellet Fuels Institute has maintained a fuel standard for over 10 years and strengthened its testing requirements in more recent years at the specific directive of EPA. We are particularly disappointed and troubled that EPA has changed course and will now allow standards that do not incorporate the very components, such as routine testing, that EPA publicly stated were essential requirements of any fuel standard to be included in the NSPS rule.”

Hedrick tells Pellet Mill Magazine that the PFI standard is superior to the other programs because PFI has a third-party accreditation program and its standards require testing every 1,000 tons. Crouch says, “The appliance manufacturers are supportive of the PFI standards. The ones I have talked with are flabbergasted that fuel allowed under the NSPS can be audited only once a year.”

Perhaps the biggest effect on readers of this publication—pellet manufacturers—is the requirement for pellets to meet one of these three standards. “Pellet-fuel manufacturers will see this has a direct impact on their industry, and manufacturers now will need to participate in a fuel-grading program,” Hedrick says. “No longer is this a voluntary program for pellet-fuel manufacturers.” Of wood pellet product produced and consumed in the U.S. today, Hedrick says just under 50 percent is part of a program qualified through PFI. There are companies qualified through ENplus, but the bulk of that is sent to the EU, and product sent to the EU won’t need to meet standards under NSPS. Hedrick says this aspect of the rule will give consumers more clarity through product labeling, since the claims on pellet bags will match what the grade is and inform consumers to the testing. “There’s a lot of confusion and misinformation out there today [with pellets],” she says.

Final Thoughts
Pellet stoves are an engineered fire, Crouch says, the keys to which are, for the fuel, knowing what each piece looks like, thanks to standards programs such as PFI’s, and for the stoves, the fan-forced air system. All organizations are still digesting the final rule and, as Hedrick says PFI is doing, developing a list of questions for EPA to gain clarity on certain aspects of the regulations. Seymour says the rule’s authors have injected confusion for manufacturers that make tremendous investments in testing and certifying their products, and EPA should address these questions quickly. He says there’s also ambiguity as to what constitutes a residential heater. Most agree, however, that the regulations will impact pellet stoves sales and design very little in the coming years. Crouch says three of the four regulated appliances—including hydronic and forced-air heaters and some wood stoves—have major issues with step-two compliance. “Cordwood hydronic heaters will be heavily impacted by the step-two emissions limits,” Seymour says. “The fuel is the limiting variable given its moisture content and overall composition compared to densified fuels like wood pellets.” Ackerly says, “I don’t think these regulations will necessarily have any impact on the number of pellet stoves sold. In the long run, I think we will see the market share of pellet stoves grow, but that is mostly due to market forces, not any government regulation.”

Very basic, inexpensive indoor and outdoor boilers will be heavily impacted. “Many of those units will be going out of production and companies will have to design new ones that will be more expensive and likely be far higher in efficiency,” Ackerly says.

Ackerly says the winner under these new regulations is the consumer, both in terms of operating costs and improved health. And when there’s winners, there’s also losers. “The losers will be the small companies who cannot produce boilers that can meet the emission standards,” he says. “Some companies will be going out of business, and customers will go to companies who make the cleaner appliances. Among the losers will be some factories in China that made the really cheap, exempt stoves. Now, the American companies that make the cleaner stoves will not have to face that competition.”

Companies that make more efficient heaters will also be winners, Ackerly says, because the NSPS requires the disclosure of efficiency for the first time. Over the next five years, consumers will have more and more access to reliable efficiency values and “that will drive sales to the companies who make the higher efficiency stoves,” he says. Scheel says HHT appreciates that there is required reporting of efficiency with no minimum, versus allowing the default efficiency to be used, as this is ultimately good for both consumers and the industry. She says HHT disagrees, however, with the requirement of carbon monoxide reporting, because as emissions are lowered, carbon monoxide levels will also be reduced. “So this requirement only sets the stage for the EPA to gather information to allow them to set another limit on wood-burning stoves in the future,” she says.

Ultimately, the NSPS is important in that it lays the groundwork to test and certify all heaters with cordwood eight years from now, during the next NSPS. It also lays the groundwork to set efficiency standards, which all other HVAC equipment have. Once testing with cordwood starts and there are minimum efficiency standards, Ackerly says wood and pellet heaters will be positioned to become mainstream energy options that can more readily be embraced by scores of programs.

Read More: Wood Pellet Hot Water Heater