3 Ton 15 SEER 97% AFUE 80,000 BTU Goodman Gas Furnace and Air Conditioner System - Downflow Review 2026

// Bottom Line

This Goodman system delivers exceptional heating efficiency at 97% AFUE and solid cooling performance at 16 SEER1, making it ideal for homeowners in moderate climates seeking energy savings without premium pricing. It's particularly well-suited for properties where space is tight and downflow configuration works with existing ductwork.

Review

This Goodman 3.5-ton system combines a high-efficiency gas furnace with a mid-tier air conditioner in a downflow configuration designed for tight installation spaces. The unit targets homeowners seeking better heating efficiency without stepping into premium price brackets. With an AHRI certificate on file (7424271) and Energy Star qualification, it represents a mainstream choice among contractors specifying Goodman equipment for moderate-climate residential applications.

The furnace delivers 80,000 BTU heating output at 97% AFUE using a modulating burner that adjusts flame intensity rather than cycling on and off, reducing temperature swings and energy waste. Cooling capacity reaches 34,800 BTU with a 16 SEER1 rating and scroll compressor running on R410A refrigerant. The variable-speed ECM blower moves up to 1,600 CFM and automatically adapts to heating and cooling demand, improving comfort and reducing runtime hours.

Pros & Cons

Pros

97% AFUE furnace efficiency reduces heating costs significantly compared to 80-90% units
16 SEER1 cooling rating exceeds many competitors at this price point
Modulating burner adjusts heating output for comfort and efficiency, not just on-off cycling
Variable-speed ECM blower motor runs quietly and adapts to demand automatically
10-year warranty with online registration provides solid peace of mind coverage
Downflow A-coil configuration works in attics and tight spaces where other units won't fit
PVC exhaust flue allows flexible, corrosion-resistant venting options

Cons

Single-stage compressor in cooling limits part-load efficiency compared to two-stage models
73.5 dBA noise level is audible, particularly during cooling cycles in quiet homes
No variable-speed compressor means less dehumidification during partial-load cooling operation

Who Should Buy

Best For

Homeowners in heating-dominant climates or those upgrading older 80-90% AFUE furnaces will appreciate the 97% efficiency and lower utility bills. Contractors installing downflow systems in space-constrained attics will find the compact 21-inch width and A-coil design invaluable.

Consider Alternatives If

Buyers in high-humidity climates needing superior dehumidification should consider two-stage cooling systems, and those sensitive to noise may prefer units rated below 70 dBA.

3 Ton 15 SEER 97% AFUE 80,000 BTU Goodman Gas Furn

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Installation

This downflow system requires proper ductwork clearance below the unit since conditioned air flows downward. The compact 21-inch width and A-coil design fit most attic spaces. Electrical needs are straightforward, 115V single-phase 60Hz with 18.7 to 30-amp breaker sizing. PVC venting to the exterior is mandatory, and pre-fab plastic flue kits simplify venting configuration. Field refrigerant charge adjustment may be needed depending on line set length.

Warranty & Reliability

Goodman provides a 10-year parts warranty when you register the unit online after installation. This covers compressor, coil, and gas valve failures but typically excludes damage from improper installation or maintenance neglect. Registration takes minutes and extends coverage substantially beyond the standard 5-year baseline, making it worthwhile for any homeowner retaining the system.

Specifications

SKU	LS38783850
Brand/Manufacturer	Online Supply
Cooling BTU	34,800
Heating BTU	80,000
Refrigerant	R410A
Electrical	115 V. 1 Phase 60 Hz
Warranty	10 Years with Online Registration
Decibel Level (dBA)	73.5
Weight (in lbs)	30.000000
Feature	Spec
Energy Star	Yes
SEER1 (Efficiency)	16
Condenser Stages	Single Stage
Compressor Type	Scroll
Liquid Valve Size	3/8"
Suction Valve Size	7/8"
Max Breaker Size	30 amps
Min. Breaker Size	18.7 amps
Tonnage	3.5 Ton
Height	34.5"
Width	21"
Depth	28.75"
Resources	Goodman Brochure Goodman Installation Instructions Goodman Parts Manual Goodman Service Manual Goodman Specifications Goodman Technical Information Goodman User Information Goodman Warranty You will need AdobeÂ® AcrobatÂ® Reader to view PDF documents.
Safety Information	PROPOSITION 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.
Configuration	Downflow/Horizontal
Liquid Line	3/8"
Suction Line	7/8"
Style	A-Coil
AHRI Certificate Number	7424271
Airflow Direction	Downflow/Horizontal
Exhaust Flue Requirement	Plastic / PVC
Product Features	Rebate Available
Furnace Efficiency / AFUE	97%
Blower Motor	Variable Speed - ECM
Maximum CFM	1600
Flue Location	Right
Burner Stages	Modulating
Fuel Type	Propane, Natural Gas
Suction Line Insulation Thickness	3/4"
Length	50 feet

Frequently Asked Questions

How does 97% AFUE compare to older furnaces in real-world heating bills? +

A 97% AFUE furnace converts 97 cents of every fuel dollar to heat, versus 80 cents for an 80% AFUE unit. Replacing a 15-year-old furnace with this model typically saves $15-25 monthly in heating costs during winter months, depending on climate and usage patterns.

Can this downflow unit work in a basement or crawlspace instead of an attic? +

Yes. Downflow configuration means air exits below the unit, making it suitable for basements, crawlspaces, and utility closets where ducts drop to lower levels. Just ensure adequate space for the 34.5-inch height and 28.75-inch depth, plus room for service access.

Is 16 SEER1 good enough for hot, humid summers? +

16 SEER1 is solid mid-tier cooling but not best-in-class. The single-stage compressor runs at full capacity even on mild days, limiting dehumidification. In very humid climates, a two-stage or variable-capacity unit may provide better moisture removal during partial-load operation.

How does the modulating burner save energy compared to standard two-stage burners? +

Modulating burners adjust flame size continuously across a range, not just high-low. This reduces temperature overshoot, minimizes short cycling, and cuts energy consumption 5-15% versus two-stage units that run at full fire until satisfied, then shut off completely.

What does the 10-year warranty actually cover if something fails? +

Parts and labor for compressor, evaporator coil, and gas furnace heat exchanger failures are covered. You must register online within a timeframe to activate extended coverage. Damage from poor installation, lack of maintenance, or refrigerant contamination is excluded.

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