Independent Review · Updated June 2026

3.5 Ton 15 SEER 97% AFUE 120,000 BTU Goodman Gas Furnace and Air Conditioner System - Horizontal

High-efficiency horizontal furnace-coil combo with modulating burner and variable-speed motor

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 120,000 BTU Goodman Gas Furnace and Air Conditioner System - Horizontal
Current Price
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// Bottom Line
This Goodman system excels for contractors installing horizontal units in attics or crawlspaces where space is tight. The 97% AFUE furnace and variable-speed ECM blower deliver solid efficiency gains, especially valuable in heating-dominant climates.

Review

Goodman's horizontal furnace and air conditioning system targets the contractor market with practical specs for attic and crawlspace installations. The 120,000 BTU heating capacity and 42,000 BTU cooling capacity address homes in moderate climates, while the compact horizontal footprint (26 inches wide, 21.125 inches deep) fits tight spaces. This unit emphasizes heating performance with its 97% AFUE rating and modulating burner technology. The system operates on both natural gas and propane, giving installers fuel flexibility on rural or underserved properties.

The 97% AFUE furnace efficiency sits among the best non-condensing alternatives and directly reduces monthly heating bills. The variable-speed ECM blower motor adapts to load conditions rather than running full-bore constantly, saving energy throughout the season. Cooling arrives via a scroll compressor with single-stage operation and R410A or R22 refrigerant compatibility. The 16 SEER2 rating meets ENERGY STAR criteria but trails high-end units approaching 18-20 SEER2. Maximum airflow of 2,000 CFM suits typical residential ductwork without oversizing concerns.

Pros & Cons

Pros

  • 97% AFUE furnace rating puts it in the high-efficiency category, reducing heating costs substantially over time
  • Modulating burner adjusts output continuously rather than simple on-off cycling, improving comfort and efficiency
  • Variable-speed ECM blower motor runs at optimal speeds for each load, consuming less energy than fixed-speed alternatives
  • PVC/plastic flue compatibility simplifies venting without expensive metal ductwork
  • 10-year warranty with online registration provides meaningful protection on major components

Cons

  • 3.5 ton cooling capacity lags behind the 5 ton furnace tonnage, creating an odd mismatch that suggests this is a furnace-only upgrade or partial replacement
  • 16 SEER2 cooling efficiency is respectable but not exceptional for modern standards, won't maximize summer energy savings
  • 73 dB noise level is moderately loud during furnace operation, noticeable in finished basements or bonus rooms

Who Should Buy

Best For

Contractors replacing furnaces in existing systems where ductwork and coil are already sized correctly. Homeowners in colder regions who prioritize heating efficiency and can justify the cost through natural gas savings over 10-15 years.

Consider Alternatives If

Anyone needing a balanced heating-cooling system should look elsewhere, since the tonnage mismatch indicates this combination may not perform optimally for both seasons.

3.5 Ton 15 SEER 97% AFUE 120,000 BTU Goodman Gas F
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Installation

This horizontal configuration requires right-side flue placement and PVC venting, both straightforward for most residential installations. Electrical demands range from 23.5 to 40 amp breaker sizing at 208/230V single-phase power. The 48-pound weight and compact dimensions make handling manageable for two installers. Refrigerant line sizing (3/8 inch liquid, 1 1/8 inch suction) and the 50-foot maximum line length are standard considerations for typical residential runs.

Warranty & Reliability

The 10-year parts warranty activates upon online registration and covers compressor, coil, and heat exchanger failures under normal conditions. This protection is industry-standard for mid-tier equipment. Warranty terms typically exclude wear items, improper installation, and lack of maintenance, so registration and proper service records matter significantly for claims.

Specifications

SKULS381183850
Brand/ManufacturerOnline Supply
Cooling BTU42,000
Heating BTU120,000
RefrigerantR410A or R22
Electrical208 / 230 V. 1 Phase 60 Hz
Warranty10 Years with Online Registration
Decibel Level (dBA)73
Weight (in lbs)48.000000
FeatureSpec
AHRI Certificate Number7424268
Airflow DirectionUpflow/Horizontal
Exhaust Flue RequirementPlastic / PVC
Product FeaturesRebate Available
Furnace Efficiency / AFUE97%
Blower MotorVariable Speed - ECM
Maximum CFM2000
ConfigurationHorizontal
Flue LocationRight
Energy StarYes
Burner StagesModulating
Fuel TypePropane, Natural Gas
Height24.5"
Width26"
Depth21.125"
ResourcesCHPF Installation Manual CHPF Specifications Sheet Goodman Evaporator Coil 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.
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
Liquid Line3/8"
Suction Line1 1/8"
StyleA-Coil
Suction Line Insulation Thickness1/2"
Length50 feet

Frequently Asked Questions

Why does this system list 5 ton tonnage but only 3.5 ton cooling capacity? +
The tonnage mismatch indicates this is likely a furnace-only replacement paired with an existing 3.5 ton coil. The furnace itself is rated higher. Verify your existing equipment before ordering to avoid incompatibility issues or undersized heating.
Can I install this in my horizontal attic space? +
Yes. The horizontal configuration with right-side flue placement and compact 26 x 21 inch footprint fits standard attic joists. Ensure adequate clearance for PVC venting and that your breaker panel supports 23.5-40 amp service nearby.
How much can I save with 97% AFUE compared to older furnaces? +
A 97% AFUE unit converts 97 cents of every gas dollar into heat. Upgrading from an 80% AFUE system saves roughly 17% on heating costs. Real savings depend on climate, usage patterns, and natural gas rates in your area.
How does this compare to Rheem or Lennox units at similar price points? +
Goodman emphasizes value over premium features. This unit matches competitor specifications in AFUE and SEER2 but typically costs less. Trade-offs include simpler controls and slightly lower noise isolation than premium brands.
What happens if my system fails after 10 years? +
The warranty expires after 10 years. You'll pay for repairs out of pocket. Plan for replacement around year 15-20 depending on maintenance and usage.

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