3.5 Ton 13 SEER 96% AFUE 100,000 BTU Goodman Gas Furnace and Air Conditioner System - Downflow Review 2026

// Bottom Line

This Goodman system works best for homeowners replacing aging equipment in mixed climates where heating loads matter as much as cooling. The 96% AFUE furnace and 13 SEER AC strike a practical efficiency balance without the premium pricing of higher-tier models.

Review

The Goodman 3.5-ton downflow gas furnace and AC system occupies the practical middle ground in residential HVAC equipment. It combines a gas furnace rated at 100,000 BTU and 96% AFUE with a 42,000 BTU air conditioner delivering 13 SEER cooling capacity. This combination targets homeowners and contractors seeking reliable performance without premium features or premium pricing. The downflow A-coil configuration makes it adaptable to various installation scenarios where space constraints matter.

Heating efficiency stands out as a key strength here. The 96% AFUE rating means 96 cents of every dollar spent on gas becomes usable heat, a meaningful advantage over standard 80-90% models. Cooling performance is respectable at 13 SEER, though not exceptional. The unit draws 115V single-phase power requiring 23.9 to 40 amp breakers, making it suitable for standard residential electrical service. Multi-speed blower capability helps balance comfort against energy consumption at part-load conditions.

Pros & Cons

Pros

96% AFUE furnace efficiency cuts heating costs significantly compared to 80-90% units
13 SEER cooling delivers solid performance for moderate climates, rating above minimum standards
Multi-speed blower motor allows modulation for comfort and efficiency optimization
Downflow A-coil configuration fits tight spaces like attics or narrow closets
10-year warranty with online registration provides substantial peace of mind protection
PVC exhaust compatibility simplifies installation in modern homes with plastic vent runs

Cons

13 SEER2 equivalent is decent but not high-efficiency; competitors offer 14-18 SEER at similar price points
Single-stage burner and compressor mean no variable output for ultra-quiet operation or part-load efficiency
75 dB noise level places it in the louder category, noticeable during operation in quiet spaces
R410A or R22 refrigerant options suggest older design; modern systems standardize on R410A or R32

Who Should Buy

Best For

Homeowners in moderate heating climates who value furnace efficiency and need a straightforward replacement without smart features or variable staging. Contractors spec-ing replacement systems for budget-conscious customers who want solid, no-frills performance will find this unit delivers reliable operation and easy installation.

Consider Alternatives If

Skip this if you need ENERGY STAR certification, live in hot climates where cooling dominates, or prefer quieter operation under 70 dB.

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

Buy at HVACDirect →

Installation

This downflow unit measures 34.5 inches tall, 21 inches wide, and 28.75 inches deep, fitting standard closet and attic installations. Refrigerant lines use 3/8-inch liquid and 7/8-inch suction ports with sweat-type valve connections. The system requires PVC exhaust venting, compatible with most modern homes. Multi-speed blower wiring demands careful attention to thermostat configuration. Goodman's installation manual provides adequate guidance for experienced technicians.

Warranty & Reliability

Goodman backs this system with a 10-year warranty upon online registration, covering parts and labor depending on your dealer's terms. This protection is solid for residential applications, giving you reasonable coverage against manufacturing defects. Registration is mandatory to activate the full term, so complete it immediately after installation. Warranty excludes normal wear, improper installation, and damage from neglect.

Specifications

SKU	LS38783830
Brand/Manufacturer	Online Supply
Cooling BTU	42,000
Heating BTU	100,000
Refrigerant	R410A or R22
Electrical	115 V. 1 Phase 60 Hz
Warranty	10 Years with Online Registration
Decibel Level (dBA)	75
Weight (in lbs)	30.000000
Feature	Spec
Energy Star	No
SEER1 (Efficiency)	13
Condenser Stages	Single Stage
Compressor Type	Reciprocating
Liquid Line	3/8"
Suction Line	7/8"
Liquid Valve Size	3/8"
Max Breaker Size	40 amps
Min. Breaker Size	23.9 amps
Tonnage	3.5 Ton
Valve Type	Sweat
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
Style	A-Coil
Airflow Direction	Downflow/Horizontal
Exhaust Flue Requirement	Plastic / PVC
Furnace Efficiency / AFUE	96%
Blower Motor	Multi Speed
Maximum CFM	2000
Flue Location	Right
Burner Stages	Single
Fuel Type	Gas
Suction Line Insulation Thickness	3/8"
Length	30 feet

Frequently Asked Questions

How does 96% AFUE compare to my current furnace? +

If you're running an 80% AFUE unit, upgrading to 96% saves approximately 16% on heating costs annually. On a $1,500 annual heating bill, expect savings around $240 per year. Over 15 years, that totals $3,600 before accounting for inflation. The payback period typically ranges 5-7 years depending on regional gas prices.

Can I use this with my existing ductwork? +

Yes, provided your ducts are sized for 2000 CFM maximum airflow. Have a technician verify duct static pressure before installation. Downflow configuration works with most residential ductwork layouts. If transitioning from a different airflow direction, duct modifications may be needed.

Is 13 SEER adequate for hot climates? +

13 SEER provides baseline cooling efficiency, adequate for mild to moderate climates. In hot climates with 200+ cooling days annually, consider 14-18 SEER models to offset higher runtime hours and peak demand charges. This unit works better in heating-dominant climates where furnace efficiency takes priority.

How does this compare to higher-SEER systems? +

A 16 SEER system costs 15-25% more but uses 18-25% less cooling energy. For homes in moderate climates running AC 1000-1500 hours yearly, the difference is modest. High-SEER units justify their cost primarily in hot climates with extended cooling seasons.

What does the 10-year warranty actually cover? +

Goodman covers manufacturing defects in parts and compressor for 10 years with registration. Labor coverage varies by dealer and typically runs 5 years. Exclusions include improper installation, refrigerant leaks from user damage, and normal wear items like blower wheels.

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