Summary of Rule Amendment Efforts
District Rule 4905 limits NOx emissions from natural gas-fired, fan-type central furnaces with rated heat inputs less than 175,000 Btu/hr and for combination heating and cooling units rated at a cooling capacity less than 65,000 Btu/hr. Unit types include condensing furnaces, non-condensing furnaces, weatherized furnaces, and furnaces installed in manufactured homes.
The District adopted Rule 4905 in 2005 and amended it in January 2015 to lower the NOx emission limit from 40 ng/J to 14 ng/J, with an associated sell through period and emission fee period to allow manufacturers time to develop new compliant furnaces. Due to the limited number of certified compliant units that would have been available by the deadline dates set in the 2015 amendment, the rule was amended in 2018 to extend the implementation period to allow the use of emissions fees in lieu of complying with the 14 ng/J limit. Before the most recent amendments to Rule 4905, the weatherized furnace emission fee option was scheduled to expire September 30, 2020. Due to the impacts of COVID-19, multiple manufacturers reported manufacturing delays or interruptions in the supply chain. Therefore, the District recently extended the emission fee period for weatherized units to September 30, 2021, consistent with the September 2020, South Coast AQMD amendments to their Rule 1111.