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

// Bottom Line

This Goodman system works well for homeowners upgrading from older equipment or contractors installing in tight spaces. The 96% AFUE furnace and 13 SEER air conditioner deliver real energy savings without premium pricing, though it's not ENERGY STAR rated.

Review

Goodman's 3.5-ton horizontal system represents the practical middle ground in residential HVAC equipment. This unit pairs a gas furnace with an air conditioner coil, making it suitable for complete system replacements where ductwork already exists. Online Supply's offering targets contractors and homeowners who prioritize reliability and straightforward installation over cutting-edge efficiency features.

The furnace delivers 100,000 BTU heating output at 96% AFUE efficiency, which is genuinely high and translates to measurable gas savings. The air conditioner side produces 42,000 BTU cooling with 13 SEER rating, meeting mid-tier efficiency standards. Single-stage operation means the compressor and burner run fully engaged rather than modulating, making the system simpler but less nuanced than two-stage alternatives.

Pros & Cons

Pros

96% AFUE furnace efficiency means lower heating bills compared to 80-90% systems, saving roughly $200-300 annually on gas
13 SEER cooling rating is solid mid-range performance, suitable for most climates outside extreme heat zones
Compact horizontal A-coil configuration fits tight attic and crawlspace installations where vertical units won't work
Multi-speed blower motor adjusts airflow from 0-2000 CFM for better comfort and zone balancing
10-year warranty with online registration provides decent protection for residential use

Cons

Single-stage compressor and burner mean the system runs at full capacity constantly, less efficient than variable-capacity competitors
75 dB noise level is moderate to moderately loud, noticeable in bedrooms or quiet spaces during cooling season
Not ENERGY STAR certified despite decent efficiency specs, limiting eligibility for some utility rebates

Who Should Buy

Best For

Homeowners replacing 15-20 year old furnace-AC combos, especially those with horizontal/attic installations or tight mechanical rooms. Contractors valuing proven Goodman reliability and straightforward serviceability in mid-range residential retrofit work will appreciate this unit's simplicity and parts availability.

Consider Alternatives If

Buyers seeking highest efficiency should look at variable-capacity systems or SEER 16+ units, and those in very hot climates may want 14+ SEER for better cooling capacity.

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

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Installation

This horizontal A-coil configuration requires 115V single-phase power with 23.9-40 amp breaker capacity, well within standard residential service. Dimensions of 34.5 inches high by 21 inches wide by 28.75 inches deep fit most attics and crawlspaces. Plastic PVC exhaust flue on the right side, 3/8-inch and 7/8-inch refrigerant lines with sweat valve connections are standard for HVAC installers.

Warranty & Reliability

Ten-year parts and labor warranty activates with online registration. This coverage is solid for residential units, covering compressor failures and heat exchanger leaks. Registration typically takes five minutes online through Goodman's portal and protects your investment substantially beyond the industry standard five-year baseline.

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	Upflow/Horizontal
Style	A-Coil
Airflow Direction	Upflow/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

What's the actual difference between 13 SEER and 16 SEER cooling? +

SEER measures cooling efficiency; 16 SEER is roughly 23% more efficient than 13 SEER. Over 15 years, upgrading costs $1,500-2,500 extra but saves $400-600 in cooling bills annually in moderate climates. Worthwhile if you're in hot regions, less critical in temperate zones.

Can I install this in my horizontal attic space myself? +

No, this requires EPA refrigerant certification and gas line work, both legally licensed contractor domains. DIY installation voids the warranty and violates building codes. Budget $1,500-2,500 for professional installation including ductwork connections and startup testing.

How does 96% AFUE compare to my current 80% furnace? +

The 16-point efficiency jump reduces heating fuel consumption roughly 20%, translating to $200-400 annual savings depending on climate and home size. Over a 15-year furnace lifespan, that's $3,000-6,000 recovered, justifying the equipment cost in most cases.

Is Goodman equipment as reliable as higher-end brands? +

Goodman owns multiple brands and manufactures solid equipment with competitive failure rates. Single-stage simplicity actually increases reliability compared to variable-capacity competitors. Service parts availability is excellent nationwide through most HVAC distributors.

Does this system qualify for tax credits or rebates? +

No ENERGY STAR rating limits federal tax credit eligibility. Check local utility rebates, which sometimes cover 96% AFUE furnaces. Some states offer modest rebates for systems exceeding minimum efficiency standards.

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