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

// Bottom Line

This horizontal Goodman system works best for homeowners replacing older units in crawl spaces or tight attic installations where the compact 21-inch height matters. It delivers respectable efficiency at a competitive price point, though it's not a premium high-SEER option.

Review

Goodman's 3.5-ton horizontal system is a workhorse unit designed for contractors and homeowners who need straightforward replacement in confined spaces. The 21-inch height makes it ideal for cramped attics or crawl space installations where standard vertical units won't fit. Online Supply positions this as a solid mid-range option balancing cooling efficiency with heating output across moderate climate zones.

The cooling side delivers 34,800 BTU with 16 SEER1 efficiency and an Energy Star badge, outperforming the advertised 15 SEER baseline. Heating pushes 80,000 BTU at 80% AFUE with two-stage burner control that modulates output for comfort. The scroll compressor is proven technology, though single-stage operation means it cycles on and off rather than ramping capacity smoothly. Expect around 73.5 dB during peak operation, which is audible but typical for units in this class.

Pros & Cons

Pros

Energy Star certified with 16 SEER1 cooling efficiency, better than the stated 15 SEER minimum
Two-stage burner on furnace allows modulating heat output for more consistent comfort and lower operating costs
Horizontal configuration fits tight installation spaces with only 21 inches of height
High-efficiency multi-speed blower motor with up to 2000 CFM maximizes airflow distribution
10-year warranty with online registration covers manufacturer defects across components

Cons

80% AFUE furnace efficiency is basic by today's standards, missing out on 90%+ high-efficiency models
Single-stage cooling compressor means the AC runs at full capacity or off, less precise than two-stage systems
R410A or R22 refrigerant flexibility suggests older design standards compared to newer R32 systems
73.5 dB noise level is moderately loud, noticeable during operation in quieter homes

Who Should Buy

Best For

Contractors and homeowners replacing 10-to-15-year-old systems in horizontal or crawl space applications will appreciate the proven Goodman reliability and straightforward installation. Budget-conscious buyers who prioritize cooling efficiency over heating performance will find the 16 SEER1 rating a good match.

Consider Alternatives If

Skip this if you need a high-efficiency furnace above 90% AFUE, want quieter operation below 70 dB, or prefer variable-capacity cooling compressors for peak summer comfort.

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

Buy at HVACDirect →

Installation

Installation requires 120V single-phase 60Hz power with a 18.7-to-30-amp breaker, standard for most homes. Suction and liquid lines use 7/8-inch and 3/8-inch connections with 50 feet of insulated suction line included. Metal exhaust flue is mandatory for gas furnace venting. Horizontal A-coil configuration fits between joists, making tight-space work manageable for experienced technicians.

Warranty & Reliability

Ten-year manufacturer coverage applies to parts when registered online, protecting against compressor failure and internal defects. This is industry-standard for Goodman units but requires immediate registration after installation. Labor and refrigerant are not covered, so factor in service call costs if repairs are needed outside the first few years.

Specifications

SKU	LS38783850
Brand/Manufacturer	Online Supply
Cooling BTU	34,800
Heating BTU	80,000
Refrigerant	R410A or R22
Electrical	120 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	21"
Width	21.125"
Depth	26"
Resources	CHPF Installation Manual CHPF Specifications Sheet Goodman Evaporator Coil Warranty You will need Adobe® Acrobat® 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.
Airflow Direction	Upflow/Horizontal
Exhaust Flue Requirement	Metal
Furnace Efficiency / AFUE	80%
Blower Motor	High Efficiency Multi-Speed
Maximum CFM	2000
Configuration	Horizontal
Burner Stages	Two
Fuel Type	Gas
Liquid Line	3/8"
Suction Line	7/8"
Style	A-Coil
Suction Line Insulation Thickness	3/4"
Length	50 feet

Frequently Asked Questions

Why does the spec sheet list both 15 SEER and 16 SEER1? +

The product title claims 15 SEER as a conservative baseline, but actual specs show 16 SEER1, which is the newer industry standard rating method. SEER1 is more stringent than old SEER ratings, so 16 SEER1 is genuinely efficient for a mid-range unit in this price category.

Can this system fit in my horizontal crawl space if I only have 18 inches of clearance? +

No. At 21 inches tall, this unit exceeds your space. You'll need either a low-profile evaporator coil setup or a vertical furnace configuration. Measure twice before ordering, as horizontal units are space-specific.

Is 80% AFUE furnace efficiency good enough for northern climates? +

It's acceptable but not ideal. Homes in cold climates benefit more from 90-plus percent AFUE models to offset heating season runtime costs. Southern and moderate climates see smaller payoff differences between 80% and 95% units.

How does this compare to a single-stage unit from a competitor? +

The two-stage burner here gives you modulating heat, meaning lower power consumption during mild winter days. Most budget competitors use single-stage burners that run full blast constantly, making this Goodman more efficient for partial-load operation.

Do I need online registration immediately after installation to get the warranty? +

Yes. The 10-year coverage is contingent on registering the unit online within a set timeframe. Without registration, coverage drops significantly, so prioritize this after your technician finishes commissioning.

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