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Mid-Size Wood Fuel Burning Equipment Regulations (350,000-3,000,000 BTU/hr heat input)

On December 16, 2022, amendments to several sections of the Vermont Air Pollution Control Regulations were adopted that relate to control of air contaminant emissions from mid-size wood fuel burning equipment. These amendments affect mid-size wood fuel burning equipment in three size categories by implementing the following requirements:

  1. 0-350,000 BTU/hr:  Units rated at or less than 350,000 BTU/hr heat input are regulated under §5-204 and are required to be EPA certified to meet the Step 2 standards (0.10 lbs total PM/million BTU heat output).  This requirement is for both residential and non-residential units.
  2. >350,000 – ≤3,000,000 BTU/hr:  Units greater than 350,000 BTU/hr heat input and less than 3,000,000 BTU/hr heat input fall under newly adopted §5-205 (Mid-size Wood Fuel Burning Equipment) and are required to meet one of the following to be sold or leased for use in Vermont:
    1. Obtain EPA certification showing they meet the Step 2 standards (mandatory by federal regulation for residential units larger than 350,000 BTU/hr heat input).
    2. Obtain VT State certification for each make and model by providing emissions test data to demonstrate the unit meets the emission limits of 0.10 lbs filterable particulate matter (PM)/ million BTU/hr heat input and 270 ppm carbon monoxide (CO) @ 7% O2 through a valid stack emission test (EPA Method 5 for PM; EPA Method 10 or equivalent for CO).  Once a specific make and model of unit has obtained VT State certification, additional identical units may be installed at other locations with a notification to the Air Quality & Climate Division.
    3. Obtain VT State certification for each make and model by demonstrating the unit is certified to European EN-303-5 Class 5 standards (this is for units up to 1,700,000 BTU/hr heat output).  For units larger than 1,700,000 BTU/hr heat output they must demonstrate the unit has been tested using EN-303-5 and meets the Class 5 standards.  The European standards and emission testing methodology are not directly comparable to EPA or state standards.  However, the European EN-303-5 Class 5 standards represent the highest standards and cleanest units available in Europe and will be accepted as demonstration of meeting the Vermont standard.

      To apply for a VT State certification, manufacturers or distributors need to complete and file an application with the Air Quality & Climate Division. A list of currently certified mid-size wood fuel burning equipment can be found here. 

      Prior to completing a sale or lease, sellers need to complete a Notice to Buyer of Mid-Size Wood Fuel Burning Equipment and file a copy with the Air Quality & Climate Division. This document notifies buyers of important requirements that apply to these units including the types of fuels the unit is certified to burn. If you will be selling or leasing mid-size wood fuel burning equipment, contact the AQCD to obtain a supply of these Notices.

      Purchasers of mid-size wood fuel burning equipment will need to maintain a record of fuel consumption. Examples of fuel consumption logs are available from the Air Quality & Climate Division in paper or electronic format. Contact the Division if you need a paper copy mailed to you.

  3. ≥3,000.000 BTU/hr:Units rated at 3,000,000 BTU/hr heat input and larger must obtain a State permit and document compliance with the emission limits through a stack test for each installation. The emission limits for units 3,000,000 – 10,000,000 BTU/hr are 0.10 lbs filterable PM /MMBTU heat input (EPA Method 5) and 270 ppm CO @ 7% O2 (EPA Method 10) and the limits for units >10,000,000 BTU/hr are 0.030 lbs filterable PM /MMBTU heat input (EPA Method 5) and 270 ppm CO @ 7% O2 (EPA Method 10).The emission limit for units between 3,000,000 and 10,000,000 BTU/hr heat input is the same as for mid-size units 350,000 to 3,000,000 BTU/hr heat input. A site-specific stack compliance test is required for each installation rated at 3,000,000 BTU/hr heat input and larger.

Please submit applications and notices to the following address:

Vermont Air Quality and Climate Division
Davis Building - 4th Floor
One National Life Drive
Montpelier, VT 05620

To contact the Air Quality & Climate Division about the wood heater and boiler regulations call the Division at 802-828-1288 or email John Wakefield at john.wakefield@vermont.gov.