40,000 BTU 80% AFUE 9-Speed Single Stage Goodman Gas Furnace Ultra-Low NOx California Model - Upflow/Horizontal



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AHRI Number:207599840

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Requires: Metal Flue Vent Piping

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The GM9S800403AU Goodman gas furnace features high-quality construction and efficient operation at a great value. The GM9S800403AU single-stage, 9-speed furnace utilizes Goodman's superior heat exchanger design to provide efficient, reliable heating to your home. If you're looking to cut your energy bills and improve your comfort without breaking the bank, your search stops with the Goodman GM9S800403AU.


  • This furnace is ideal to heat a smaller house (depending on climate)
  • 40,000 BTU 80% efficient natural gas furnace
  • Requires metal flue venting
  • Can be used in the upflow or horizontal (right or left) orientation
  • Ultra Low-NOx Compliant for California
  • Innovative design for electrical efficiency, safety, and lower sound output

Ultra-Low NOx Compliant

In California, many counties have a lower NOx emission requirement than the rest of the United States. The GM9S800403AU Goodman gas furnace is California Ultra-Low NOx compliant. With a built-in low emission filter and special venting system, this Goodman gas furnace produces less nitrogen oxides to be released into the atmosphere, lowering the overall amount of toxic greenhouse gases output of the average California home.

Ultra-Low NOx furnaces are required for gas furnace installations in the following counties in California: Fresno, Joaquin, Kern, Kings, Los Angeles, Madera, Merced, Orange, Riverside, San Bernardino, San Stanislaus, and Tulare. If you have any questions, please contact us.

40,000 BTU

The GM9S800403AU Goodman gas furnace is 40,000 BTU’s. This BTU count is a measure of the input of the furnace per hour, while the output of this furnace is 32,000 BTU’s (40,000 X 80% AFUE) per hour. In ideal climate conditions, this 40,000 BTU furnace is usually used to heat a small house.

80% Efficiency Rating

The GM9S800403AU Goodman gas furnace is 80% efficient, and the standard furnace efficiency on the market today. This means that 80% of the gas going into the furnace is used to heat your home and the remaining 20% is lost out of the flue venting. Please note that all 80% furnaces must be vented using metal flue venting, while anything higher than 90% efficient must be vented using plastic/PVC venting.

Ultra-low NOx furnaces are only available in natural gas configurations. If you need a propane furnace, you will need to order the regular version of this furnace and add a propane conversion kit to it. You can find the regular version here: GM9S800403AN

Single Stage Furnace

The GM9S800403AU Goodman gas furnace is a single stage furnace has only one heat output. Regardless of the indoor temperature, this furnace will burn at 100% output whenever the thermostat calls for it. Like a light switch, this furnace’s burner will either be on or off and nothing in between. A single stage furnace is the standard efficient furnace since every time your furnace turns on the furnace uses the same amount of energy.

9-Speed ECM Blower Motor

Instead of the last generation PSC blower motor, the GM9S800403AU utilizes a multi-speed ECM motor, which uses less power and provides smarter air circulation. All of this causes an overall increase in the electrical efficiency of your furnace, which saves you money.


With installation that follows your state and local codes and with online registration, all Goodman furnaces come with a 10-year parts and lifetime heat exchanger warranty through the manufacturer.

Self-Diagnostic Control Board

The Goodman brand has improved technology from years of production experience, allowing for a long-lasting product that rarely has any issues. However, if something does go wrong on the furnace, the control board has a set of sensors that allow it to diagnose basic issues, allowing for easy troubleshooting and to notify the owner if basic maintenance or warranty work is recommended. This increases the overall safety of the unit, for the furnace itself and the occupants of the home where it is installed.

Ease of Installation

The value of modern Goodman furnaces doesn't end at efficiency. Today’s Goodman furnaces feature many different connection options to reduce installation. The GM9S800403AU model has a more universal design, which consists of its ability to be installed in both an upflow or horizontal (right or left) configuration. This allows for an easier installation in more locations, from your attic to your basement. The furnace also comes with color-coded low-voltage terminals that allow for a shorter and easier installation time, which decreases installation costs.

Product Specifications

More Information
40,000 BTU 80% AFUE 9-Speed Single Stage Goodman Gas Furnace Ultra-Low NOx California Model - Upflow/Horizontal
AHRI Certificate Number207599840
Config SearchUpflow/Horizontal
Exhaust Flue RequirementMetal
Furnace Efficiency / AFUE 80%
Heating BTU40,000
Blower Motor9 Speed
Maximum CFM1200
Electrical115 V. 1 Phase 60 Hz
PhaseSingle Phase
Low NOxUltra Low NOx
Burner StagesSingle
Fuel TypeNatural Gas
Height33 3/8"
Warranty10 Years with Online Registration
Resources You will need Adobe® Acrobat® Reader to view PDF documents.
Safety Information
This gas appliance requires a trained technician to install. Improperly connecting gas lines or improperly connecting a gas flue or venting may result in death. By purchasing this item, you are agreeing that you are using a trained technician to install this gas appliance. We will not be responsible for any injury or property damage arising from improper service or service procedures. Whoever installs or services this unit assumes responsibility for any personal injury or property damage which may result. Many jurisdictions require a license to install this equipment.



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For over three decades Goodman has concentrated on something more important than simple brand recognition consumer advertising. They focus on the design, engineering, and manufacturing of dependable products that have helped millions and millions of homeowners achieve reliable, high-quality, and affordable indoor comfort. In addition, Goodman has earned the loyalty and respect from thousands of local independent heating and cooling professionals across North America.