Colorado’s New Propane Equipment NOx Standards Take Effect in 2026

Editor’s Note: The following news about Colorado propane NOx equipment standards first appeared in the National Propane Gas Association’s (NPGA) The Bobtail.  

On Jan. 1, 2026, House Bill 23-1161 went into effect in Colorado. The legislation, which passed in 2023, seeks to reduce NOx emissions from gas furnaces and water heaters. However, the statute calls for the utilization of an emissions test that relies on protocols that were developed for natural gas products, not propane. This has created a compliance headache for manufacturers. As of the new year, retailers may not sell, lease or distribute non-compliant equipment in the state market (there is a grace period for products held in inventory before Jan. 1, 2026).

Colorado propane NOx equipment standards:

• Water heaters with a rated heat input capacity < 75,000 BTUs per hour and for any unit with power assist: 10 nanograms of NOx per joule;
• Water heaters with a rated heat input capacity > 75,000 BTUs and < 2 million BTUs per hour: 14 nanograms of NOx per joule;
• Fan-type central furnaces: 14 nanograms of NOx per joule.

Tom Clark, executive director of the Colorado Propane Gas Association, has been engaging and seeking clarity from the Polis Administration on implementation of HB23-1161 for months. “This clarification was critical and I’m glad we got it for members,” said Clark. “The statute unintentionally tied affected propane furnaces and water heaters to testing protocols created for natural gas equipment, creating an impossible compliance standard for propane manufacturers. While we are happy that state officials confirmed that propane products that are certified to the most recent version of the federal Energy Star Program are automatically deemed to comply with the new emission limits, we need to work with the legislature to ensure that all propane products in the market remain available to Colorado consumers.”

As of the 2024 industry sales report, Colorado is the 18th largest propane market in the country, with 186 million gallons sold. For more information, contact NPGA’s senior director of state advocacy & affairs, Jacob Peterson.