Meet California’s NOx emission requirements with our 80% AFUE, metal-vented (non-condensing) gas furnaces, available in Low NOx and Ultra-Low NOx (ULN) versions for code-compliant installs depending on county.

What is NOx?
NOx stands for Nitrogen Oxides—smog-forming pollutants produced during combustion that contribute to ground-level ozone and respiratory irritation. California air districts set appliance emission limits to reduce NOx and improve air quality.

What is AFUE (briefly)?
AFUE = Annual Fuel Utilization Efficiency. An 80% AFUE furnace turns about 80% of the fuel into usable heat (about 20% exits the flue as waste). These are metal-vented, non-condensing furnaces that use B-vent or single-wall metal venting—ideal where high-efficiency PVC venting isn’t required or feasible.

Where Ultra-Low NOx (14 ng/J) Furnaces Are Required in California

Two California air districts currently require Ultra-Low NOx (14 nanograms per Joule) emissions for residential fan-type central furnaces:

1. South Coast AQMD (Rule 1111 – 14 ng/J)
   Counties/areas: Most of Los Angeles County (except Antelope Valley), all of Orange County, the western/urban portions of San Bernardino and Riverside Counties. South Coast AQMD Rules

2. San Joaquin Valley APCD (Rule 4905 – 14 ng/J)
   Counties: San Joaquin, Stanislaus, Merced, Madera, Fresno, Kings, Tulare, and the valley portion of Kern County. San Joaquin Valley APCD Rules

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   Translation for shoppers/installers:

   1. If your install address is in South Coast AQMD or San Joaquin Valley APCD, choose an Ultra-Low NOx (14 ng/J) model to pass inspection.