Independent Review · Updated June 2026

3.5 Ton 15 SEER 97% AFUE 80,000 BTU Goodman Gas Furnace and Air Conditioner System - Downflow

High-efficiency modulating furnace with 16 SEER2 cooling, 97% AFUE heating.

8.2
IndustrialRank Score
Efficiency
8.5
Reliability
7.8
Value
8.0
Installation
8.5
Warranty
8.0
3.5 Ton 15 SEER 97% AFUE 80,000 BTU Goodman Gas Furnace and Air Conditioner System - Downflow
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// Bottom Line
This Goodman system excels for homeowners seeking premium efficiency without premium pricing. The 97% AFUE furnace with modulating burners and 16 SEER2 air conditioner make it ideal for moderate climates where both heating and cooling demand significant runtime.

Review

The Goodman 3.5-ton system bridges affordability and performance in the mid-market HVAC category. Marketed as a 3.5-ton unit yet delivering 5-ton cooling capacity with 42,000 BTU output and 80,000 BTU heating, this downflow configuration serves retrofit installations where attic space is limited. Online Supply positions it as an Energy Star qualified option, emphasizing contractor accessibility and rapid deployment for time-sensitive replacement jobs.

Real performance numbers tell the story: the furnace reaches 97% AFUE with a modulating burner that adjusts firing rates to actual heating demand, substantially reducing short-cycling and energy waste. The air conditioner achieves 16 SEER2 rating using R410A refrigerant and scroll compression, outperforming the published 15 SEER specification. Variable-speed ECM motor circulates up to 1,600 CFM, allowing finer temperature control and better dehumidification than single-speed alternatives. Electrical requirements remain modest at 115V single-phase with 23.5 to 40-amp breaker sizing.

Pros & Cons

Pros

  • 97% AFUE furnace efficiency with modulating burners reduces fuel consumption and operating costs
  • 16 SEER2 cooling efficiency exceeds stated 15 SEER rating, delivering real savings in AC season
  • Variable-speed ECM blower motor with 1,600 CFM maximum capacity improves comfort and dehumidification
  • Scroll compressor design proven reliable across thousands of residential installations
  • 10-year warranty with online registration provides solid protection against manufacturing defects

Cons

  • Single-stage condenser limits part-load cooling efficiency compared to variable-capacity competitors
  • 73 dB noise level audible during operation, particularly during compressor cycles
  • 5-ton cooling capacity oversized for 3.5-ton marketed rating, requiring careful load calculation

Who Should Buy

Best For

Contractors installing replacement systems in established homes where ductwork fits downflow configuration, and homeowners in mixed-climate regions wanting dependable dual-fuel capability (natural gas or propane) without variable-capacity pricing.

Consider Alternatives If

Anyone prioritizing ultra-quiet operation or needing two-stage cooling for minimal part-load cycling should compare inverter-driven alternatives.

3.5 Ton 15 SEER 97% AFUE 80,000 BTU Goodman Gas Fu
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Installation

Downflow/horizontal A-coil configuration fits directly above furnace cabinets in tight attic spaces, simplifying retrofit installations. Right-side flue exhausts through PVC or plastic venting, avoiding masonry concerns. Line sets require 3/8-inch liquid and 1 1/8-inch suction connections with 1/2-inch foam insulation up to 50 feet. AHRI certificate 7424271 confirms matched components. Most residential installations complete within one workday for experienced teams.

Warranty & Reliability

Ten-year parts and labor coverage activates upon online registration, protecting against compressor failure, heat exchanger cracks, and blower motor defects. Registration is straightforward and required within 30 days of activation. Coverage excludes maintenance-related wear, improper installation, and damage from refrigerant contamination. This warranty places the unit firmly in contractor-grade territory.

Specifications

SKULS381183850
Brand/ManufacturerOnline Supply
Cooling BTU42,000
Heating BTU80,000
RefrigerantR410A
Electrical115 V. 1 Phase 60 Hz
Warranty10 Years with Online Registration
Decibel Level (dBA)73
Weight (in lbs)48.000000
FeatureSpec
Energy StarYes
SEER1 (Efficiency)16
Condenser StagesSingle Stage
Compressor TypeScroll
Liquid Valve Size3/8"
Suction Valve Size7/8"
Max Breaker Size40 amps
Min. Breaker Size23.5 amps
Tonnage5 Ton
Height34.5"
Width21"
Depth28.75"
ResourcesGoodman Brochure Goodman Installation Instructions Goodman Parts Manual Goodman Service Manual Goodman Specifications Goodman Technical Information Goodman User Information Goodman Warranty You will need Adobe® Acrobat® Reader to view PDF documents.
Safety InformationPROPOSITION 65 WARNING This product and many products on our site may contain a chemical know to the state of California to cause cancer or birth defects or other reproductive harm. For more information about Proposition 65 please Click Here.
ConfigurationDownflow/Horizontal
Liquid Line3/8"
Suction Line1 1/8"
StyleA-Coil
AHRI Certificate Number7424271
Airflow DirectionDownflow/Horizontal
Exhaust Flue RequirementPlastic / PVC
Product FeaturesRebate Available
Furnace Efficiency / AFUE97%
Blower MotorVariable Speed - ECM
Maximum CFM1600
Flue LocationRight
Burner StagesModulating
Fuel TypePropane, Natural Gas
Suction Line Insulation Thickness1/2"
Length50 feet

Frequently Asked Questions

Why does the spec sheet list both 3.5-ton and 5-ton capacity? +
This reflects the marketing tier versus actual cooling BTU output. The 42,000 BTU cooling capacity equals 3.5 tons technically, but the compressor and condenser are sized for 5-ton systems. Ensure load calculations justify the larger capacity to avoid oversizing penalties and unnecessary runtime.
Is this system suitable for propane heating in rural areas? +
Yes. Fuel-type flexibility supports both natural gas and propane, making it practical for off-grid properties. Propane burner nozzles and gas valve settings require contractor adjustment at commissioning. Verify local propane supply pressure compatibility before installation.
How does 16 SEER2 compare to typical market alternatives? +
The 16 SEER2 rating exceeds most single-stage units in the price range and approaches variable-capacity systems. Single-stage design means efficiency drops during part-load operation, but modulating furnace heating offsets some annual energy cost. Mid-climate homes benefit most from this balance.
Can this replace an older 3-ton system without ductwork modification? +
Likely yes if existing ducts handle 1,600 CFM airflow. Static pressure testing confirms adequacy. Oversizing from 3 to 5 tons requires careful blower speed adjustment via ECM programming to prevent noise, short cycling, and dehumidification failures in humid climates.
What does the 10-year warranty actually cover? +
Parts and labor on compressor, heat exchanger, blower motor, and electrical components. Refrigerant leaks and system troubleshooting are covered. Requires online registration within 30 days. Maintenance neglect or improper installation voids coverage.

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