02/10/2026
Colorado as of January 1, 2026: new heating system install requirements.
• Colorado does NOT set a specific number (like “90% minimum”) in the law. Instead, the rule requires Ultra-Low NOx emissions or ENERGY STAR® certification.
• Nearly all furnaces that meet those requirements are high-efficiency, condensing furnaces.
Most compliant furnaces are ~95% AFUE or higher
Standard 80%furnaces are effectively out for new installs once pre-2026 inventory is gone.
Bottom line: if you currently have a heating system with a metal flue pipe, when it is replaced it will beed to be a high efficiency heating system with a PVC flue pipe. This will add additional costs and new flue pipe configurations to accommodate the requirement. Please make sure you use a trustworthy HVAC company when replacing your heating system.
