• District Rule 4905
    Natural Gas-Fired, Fan-Type Central Furnaces

Summary of Rule Amendment Efforts

District Rule 4905 is a point-of-sale rule that limits NOx emissions from natural gas-fired, fan-type central furnaces that has been imperative to reducing emissions from this source category.

Per commitments in the 2008 PM2.5 Plan, 2012 PM2.5 Plan and the 2013 Plan for the Revoked 1-Hour Ozone Standard, the rule was amended in 2015 to lower the NOx emission limit from 40 nanograms/Joule (ng/J) to 14 ng/J, with an associated sell-through period and emissions fee period to allow manufacturers time to develop new compliant furnaces. Manufacturers have successfully developed the necessary technologies to meet the 14 ng/J limit for all unit types, except for those used in manufactured homes due to various challenges. On March 19, 2026, the District adopted an extension of the emission fee period for the manufactured home furnace category to provide additional time for the development of compliant furnace technologies.

District Contact

Recent and Upcoming Public Meetings

Date & Time Notice Materials
Wednesday, January 21, 2026 at 4:30 PM   Notice of Public Workshop

Presentation (English) 

Presentation (Spanish)
Thursday, March 19, 2026 at 9:00 AM  Notice of Public Hearing 

Proposed Rule 4905 

Draft Staff Report 

Final Rule

Title/Description Amended Date Items
Rule 4905 - Natural Gas-Fired, Fan-Type Central Furnaces  March 19, 2026 Final Rule

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