Do I need a permit to operate an air curtain burner?
In most states, yes. Temporary use (typically up to 6 months at one location) requires a burn permit from the local fire marshal or state forestry department. Longer-term or stationary use may require Title V air quality compliance. Requirements vary by state, county, and proximity to structures. We have sold and commissioned Merris units across the country and can tell you what permit process other contractors in your state have gone through. Call us at 770-433-2670 before you buy.
What is the difference between an air curtain burner and open burning?
Open burning is uncontained combustion — the smoke, particulates, and gases escape directly into the air. An air curtain burner uses a high-velocity air manifold to force secondary combustion at temperatures above 1,800°F. That secondary burn re-combusts the particulates and gases before they can escape. The visible result is near-smokeless operation. The regulatory result is EPA 40 CFR Part 60 compliance — the machine meets federal standards that open burning does not.
Can I burn stumps in the Merris WX-5 or WX-8?
Yes. Stumps, root balls, and large-diameter logs are standard material for both the WX-5 and WX-8. The 6’3″ door opening on both models accepts most material without pre-processing. Very large stumps may need to be split or broken before loading, depending on diameter. There is no restriction on green or wet wood — moisture affects burn rate but not compliance.
What materials cannot go in an air curtain burner?
Pressure-treated lumber, plywood, painted or stained wood, creosote-treated timber, railroad ties, utility poles, plastics, C&D debris, and engineered wood products are prohibited under EPA 40 CFR Part 60. This is a federal requirement that applies regardless of model or burn rate. Burning prohibited materials is an EPA violation. If your material is clean, untreated natural wood and vegetative debris, you are in the approved category.
How much ash does an air curtain burner produce?
Approximately 98% volume reduction. A rough benchmark: 5,000 tons of debris produces approximately 3 tons of ash — roughly 6 cubic yards. The exact ratio varies by material density, moisture content, and burn conditions. Ash can be spread on-site, amended into topsoil blends, or under specific conditions processed as biochar. It is not classified as hazardous waste from clean wood burning.
What is the difference between the WX-5 and the WX-8?
Burn rate and firebox size. The WX-5 processes 3 to 6 tons per hour and weighs 18,000 lbs. The WX-8 processes 6 to 9 tons per hour and weighs 24,000 lbs. Both have the same 6’3″ loading height. The WX-8’s firebox is 8 feet longer, which means it accepts larger material and runs a higher burn rate without constant loading. The WX-5 is the right size for 1 to 3 acre daily clearing. The WX-8 is built for production-volume corridor clearing and large site prep.
How does the operating cost compare to a horizontal grinder?
At 5,000 tons per year, the WX-8 runs at approximately $21.76 per ton all-in — fuel, one operator, and equipment amortization. A comparably capable horizontal grinder runs approximately $85 per ton, and requires a dedicated mechanic, a service truck, and a carbide tip budget that now runs $15,000 to $20,000 per year. The grinder makes sense if you have a reliable wholesale mulch market. If your goal is disposal — getting the material gone at the lowest cost — the WX-8 is $63 cheaper per ton.
Can the Merris be rented instead of purchased?
Screen USA does not rent equipment directly. If you need a rental unit, our rental directory connects you with rental providers who carry air curtain burners.
