Independent Review · Updated June 2026

3.5 Ton 13 SEER 96% AFUE 100,000 BTU Goodman Gas Furnace and Air Conditioner System - Downflow

Solid 96% AFUE furnace with 13 SEER cooling for budget-conscious homeowners.

8.2
IndustrialRank Score
Efficiency
8.5
Reliability
7.8
Value
8.0
Installation
8.5
Warranty
8.0
3.5 Ton 13 SEER 96% AFUE 100,000 BTU Goodman Gas Furnace and Air Conditioner System - Downflow
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// Bottom Line
This Goodman system delivers strong heating efficiency at 96% AFUE with respectable 13 SEER cooling, making it ideal for homeowners replacing older equipment who want reliable performance without premium pricing. The downflow A-coil configuration works well in attic or basement installations where space is tight.

Review

The Goodman 3.5 Ton gas furnace and air conditioner system represents a practical middle ground in residential HVAC. While product listings show some spec confusion (tonnage marked as both 3.5 and 5), the core equipment delivers what contractors expect from Goodman, a brand known for reliable workhorse equipment rather than premium performance. The downflow A-coil configuration fits attic and basement installations where headroom matters.

Performance metrics tell a solid story. The 96% AFUE rating significantly outpaces 80-85% units common in older homes, translating to real heating savings. On cooling, the 42,000 BTU capacity with 13 SEER provides adequate performance for moderate climates, though it trails 16+ SEER units gaining popularity. The reciprocating compressor uses R410A or R22 refrigerant and runs as a single-stage unit, meaning it powers full capacity when running rather than modulating output. Multi-speed blower handling up to 2000 CFM adjusts to actual demands.

Pros & Cons

Pros

  • 96% AFUE heating efficiency reduces gas bills significantly compared to 80-85% units
  • 42,000 cooling BTU with 13 SEER provides balanced seasonal performance for moderate climates
  • Multi-speed blower motor adapts airflow to actual heating/cooling demand
  • 10-year parts warranty with online registration offers solid peace of mind
  • PVC flue compatibility simplifies venting and reduces installation costs

Cons

  • 13 SEER is adequate but not premium, higher SEER models save more on cooling costs
  • Single-stage compressor cycles on/off rather than modulating, less efficient than two-stage units
  • 75 dB noise level is moderately loud, some homeowners may notice operation
  • Not ENERGY STAR certified, meaning efficiency lags best-in-class alternatives

Who Should Buy

Best For

Contractors and homeowners replacing 15+ year old systems in mixed climates who prioritize heating efficiency and value straightforward installation. This unit suits homes where cooling demands are moderate and budget constraints prevent SEER 16+ equipment.

Consider Alternatives If

Anyone in hot climates needing aggressive cooling, homes seeking ENERGY STAR certification, or buyers who want cutting-edge variable-capacity technology.

3.5 Ton 13 SEER 96% AFUE 100,000 BTU Goodman Gas F
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Installation

Installation is straightforward for licensed contractors. The downflow/horizontal configuration with A-coil design suits basement or attic placement. PVC flue compatibility simplifies venting versus metal duct requirements on older units. You'll need 23.9 to 40 amp electrical service at 115V single phase. Refrigerant lines measure 3/8 inch liquid and 7/8 inch suction with sweat valve connections, standard for this tonnage class.

Warranty & Reliability

Ten-year parts coverage with online registration provides solid protection against manufacturing defects. This is respectable but not exceptional, as some competitors offer 10 years parts plus 5-year labor. The warranty protects component failure but not wear items like filter media or seasonal maintenance costs.

Specifications

SKULS38783830
Brand/ManufacturerOnline Supply
Cooling BTU42,000
Heating BTU100,000
RefrigerantR410A or R22
Electrical115 V. 1 Phase 60 Hz
Warranty10 Years with Online Registration
Decibel Level (dBA)75
Weight (in lbs)30.000000
FeatureSpec
Energy StarNo
SEER1 (Efficiency)13
Condenser StagesSingle Stage
Compressor TypeReciprocating
Liquid Line3/8"
Suction Line7/8"
Liquid Valve Size3/8"
Max Breaker Size40 amps
Min. Breaker Size23.9 amps
Tonnage5 Ton
Valve TypeSweat
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
StyleA-Coil
Airflow DirectionDownflow/Horizontal
Exhaust Flue RequirementPlastic / PVC
Furnace Efficiency / AFUE96%
Blower MotorMulti Speed
Maximum CFM2000
Flue LocationRight
Burner StagesSingle
Fuel TypeGas
Suction Line Insulation Thickness3/8"
Length30 feet

Frequently Asked Questions

What's the actual tonnage, 3.5 or 5 tons? +
Specs show conflicting data, but the 42,000 cooling BTU output indicates 3.5-ton capacity. Contact the supplier for clarification before purchase. This discrepancy suggests outdated product database entries rather than mislabeling.
Can this system work in my attic installation? +
Yes. The downflow A-coil configuration fits attic placement well. At 34.5 inches tall and 30 pounds, it requires modest space. Ensure adequate return air plenum below the unit and confirm PVC vent line routing to exterior before purchase.
How does 96% AFUE compare to newer high-efficiency furnaces? +
96% AFUE is very good but not top-tier. Premium units reach 98% AFUE. The 2-3% difference means modest annual savings on heating bills, roughly $100-200 depending on climate and usage patterns.
Should I choose this or a higher SEER unit? +
At 13 SEER, this unit costs less upfront. In moderate climates, payback is reasonable. In hot climates, 16+ SEER units save more over 15 years despite higher initial cost. Calculate based on your cooling season length.
Is the 10-year warranty enough? +
Yes for parts, though some competitors add labor coverage. Most failures occur in years 1-3, so 10 years parts provides solid protection. Budget separately for extended labor warranties if desired.

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