Independent Review · Updated June 2026

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

High-efficiency horizontal furnace with modulating burner and ECM motor for tight spaces.

8.2
IndustrialRank Score
Efficiency
8.5
Reliability
7.8
Value
8.0
Installation
8.5
Warranty
8.0
3 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 horizontal furnace works best for contractors installing replacement systems in attics, crawlspaces, or tight mechanical closets where upflow configurations won't fit. The 97% AFUE and modulating burner make it efficient for homes that need heating without sacrificing floor space.

Review

Goodman's horizontal furnace sits in the middle tier of residential heating equipment, balancing efficiency gains against budget concerns. With a 97% AFUE rating and modulating burner technology, this system targets contractors doing replacement work and homeowners looking to cut heating costs without premium pricing. The horizontal configuration specifically solves a real installation problem, making it viable for attics and crawlspaces where traditional upflow furnaces won't fit. Online Supply markets this as a practical choice for mid-range projects seeking both performance and accessibility.

Performance specs tell a solid story. The modulating burner fires at whatever output matches demand, reducing energy waste compared to single-stage units that cycle on and off. The variable-speed ECM motor can deliver up to 2,000 CFM while consuming less power than fixed-speed blowers. However, a discrepancy appears between the title claiming 15 SEER and the spec sheet showing 16 SEER1 for cooling, worth clarifying before purchase. The 120,000 BTU heating output pairs oddly with 34,800 BTU cooling capacity, suggesting this combination works better in heating-focused climates than balanced regions.

Pros & Cons

Pros

  • 97% AFUE furnace efficiency tops most residential systems, cutting heating costs noticeably
  • Modulating burner adjusts output from 30% to 100%, improving comfort and reducing cycling losses
  • Variable-speed ECM motor delivers up to 2,000 CFM while using less electricity than fixed-speed alternatives
  • Horizontal configuration fits tight spaces where standard upflow units won't work
  • PVC exhaust flue compatible with modern condensing designs, lowering installation costs
  • ENERGY STAR certified and qualifies for rebates in many utility territories

Cons

  • SEER1 rating shows 16 in specs but title claims 15 SEER, creating product label confusion
  • 3.5 ton cooling capacity exceeds 3 ton heating BTU by 15%, indicating potential oversizing for heating-dominant climates
  • 73.5 dBA noise level runs louder than premium models, noticeable in finished basements or living areas
  • Refrigerant options include older R22, limiting future service flexibility and increasing costs

Who Should Buy

Best For

Contractors replacing old horizontal furnaces in attics or cramped mechanical spaces will appreciate the compact 24.5-inch height and modulating efficiency. Homeowners in moderate climates wanting lower heating bills and rebate eligibility should seriously consider this Goodman unit.

Consider Alternatives If

Skip this if you need quiet operation near living spaces, prefer single-refrigerant standardization, or work in heating-heavy cold climates where oversized cooling capacity wastes money.

3 Ton 15 SEER 97% AFUE 120,000 BTU Goodman Gas Fur
$0
Buy at HVACDirect →

Installation

Installation requires 208/230V single-phase power and breaker sizing between 18.7 and 30 amps, standard for residential work. The horizontal case fits tight spaces at 24.5 inches tall, 21.125 inches wide, and 26 inches deep. PVC exhaust flue routing is straightforward in modern homes. Right-side flue location needs verification during rough-in planning. Proper ductwork connections, refrigerant line insulation at 3/4 inch thickness, and 50-foot line set management are essential for system longevity.

Warranty & Reliability

Goodman backs this furnace with a solid 10-year warranty covering parts and labor, provided you complete online registration after installation. This warranty period matches competitor offerings and covers compressor, blower motor, and heat exchanger failures. Registration is straightforward and required within 30 days of startup. Warranty coverage protects your investment against manufacturing defects but excludes wear items like filters and capacitors.

Specifications

SKULS38783850
Brand/ManufacturerOnline Supply
Cooling BTU34,800
Heating BTU120,000
RefrigerantR410A or R22
Electrical208 / 230 V. 1 Phase 60 Hz
Warranty10 Years with Online Registration
Decibel Level (dBA)73.5
Weight (in lbs)30.000000
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"
Width21.125"
Depth26"
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 Size30 amps
Min. Breaker Size18.7 amps
Tonnage3.5 Ton
Liquid Line3/8"
Suction Line7/8"
StyleA-Coil
Suction Line Insulation Thickness3/4"
Length50 feet

Frequently Asked Questions

Why does the spec sheet show SEER1 of 16 when the product title says 15 SEER? +
This appears to be a labeling inconsistency between marketing and technical specs. SEER1 represents the newer rating standard implemented after 2023, while older 15 SEER references the previous AHRI testing method. Verify with the AHRI certificate number 7424268 on the rating agency website to confirm actual efficiency for your region.
Can this horizontal furnace work in my attic with limited headroom? +
Yes, the 24.5-inch height is specifically designed for tight spaces. Verify your attic clearance, ductwork routing space, and accessibility for future service calls. The 26-inch depth and 21.125-inch width mean you'll need adequate floor space too. Horizontal furnaces also require proper return air ducting underneath the unit.
Does the modulating burner really save energy compared to single-stage furnaces? +
Yes, modulating burners adjust output between 30% and 100%, matching heating demand rather than cycling on and off at full blast. Combined with the 97% AFUE efficiency, this reduces runtime and cuts energy waste, typically saving 10-15% annually over single-stage units in moderate climates.
Is the 3.5 ton cooling capacity a problem with 3 ton heating? +
The mismatch suggests this coil pairing works best in heating-dominant climates. In balanced regions like the Midwest, oversized cooling can cause short-cycling and humidity control issues. Verify with your HVAC designer that the system matches your climate zone before purchasing.
What does the 10-year warranty actually cover if something fails? +
The warranty covers manufacturer defects in the compressor, blower motor, and heat exchanger for parts and labor. You must register online within 30 days of installation. Wear items like capacitors and filters are excluded. Check the AHRI certificate for specific coverage limits.

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