3.5 Ton 15 SEER 96% AFUE 120,000 BTU Goodman Gas Furnace and Air Conditioner System - Downflow Review 2026

// Bottom Line

This Goodman system makes sense for contractors and homeowners in moderate climates seeking reliable heating and cooling without premium pricing. The 96% AFUE furnace and 15 SEER air conditioner deliver real efficiency gains, especially in homes requiring downflow configuration in attics or tight spaces.

Review

Goodman's 3.5-ton gas furnace and air conditioner system represents a straightforward, well-engineered choice in the mid-market HVAC segment. At $3136, it delivers credible efficiency ratings, Energy Star certification, and a respectable 10-year warranty. This SKU LS381183850 targets contractors and homeowners who prioritize reliable performance without paying for luxury features. The downflow configuration and compact 30-inch height open installation possibilities in tight spaces where standard units don't fit.

Performance-wise, the 96% AFUE furnace converts almost all fuel to usable heat, producing 120,000 BTU with two burner stages for modulating output. Cooling capacity reaches 42,000 BTU at 15 SEER efficiency using R410A refrigerant and a scroll compressor. The variable-speed ECM blower motor handles up to 2000 CFM, adjusting speed to match heating and cooling demand. These specs deliver balanced performance for moderate climates without oversizing or undersizing typical residential applications.

Pros & Cons

Pros

96% AFUE furnace efficiency means lower heating bills, particularly valuable in cold climates where furnace run time is significant
Variable-speed ECM blower motor adjusts airflow between 0 and 2000 CFM, reducing energy waste during partial-load operation
Two-stage burner provides modulating heat output, improving comfort and reducing cycling
Compact 30-inch height fits downflow applications in attics and tight closets where standard upflow units won't work
Energy Star certified with 10-year warranty when registered, covering both heating and cooling components

Cons

15 SEER rating is good but not exceptional, newer models reach 16+ SEER at similar price points
Single-stage condenser means cooling doesn't modulate, causing more on-off cycling in moderate outdoor temps
73 dB noise level is audible from adjacent rooms, slightly louder than premium competitors

Who Should Buy

Best For

Contractors installing systems in homes with attic space constraints or existing downflow ductwork will appreciate the compact 30-inch height and reliable Goodman components. Homeowners in northern climates upgrading from 80% AFUE furnaces will see meaningful utility savings with the 96% efficient furnace, potentially recovering costs within 5 to 7 years.

Consider Alternatives If

Buyers in cooling-dominant regions (Florida, Arizona, Texas) should look for higher SEER ratings like 17+ to maximize AC efficiency where units run most of the year.

3.5 Ton 15 SEER 96% AFUE 120,000 BTU Goodman Gas F

$3136

Buy at HVACDirect →

Installation

Installation requires 208-230V single-phase 60 Hz power with 23.5 to 40 amp breaker capacity. Downflow orientation suits attics and utility closets with adequate return air clearance. Plastic PVC exhaust venting is standard. Refrigerant lines include a 50-foot suction line with 1/2-inch insulation, covering most residential runs. Proper ductwork sizing and commissioning are critical to achieve rated efficiency.

Warranty & Reliability

Goodman backs this system with a 10-year parts warranty upon online registration, a meaningful commitment at this price tier. Coverage includes the compressor, furnace heat exchanger, and evaporator coil. Warranty transfers if you sell the home, adding resale appeal. Registration is straightforward but required to activate full coverage.

Specifications

SKU	LS381183850
Brand/Manufacturer	Online Supply
Cooling BTU	42,000
Heating BTU	120,000
Refrigerant	R410A or R22
Electrical	208 / 230 V. 1 Phase 60 Hz
Warranty	10 Years with Online Registration
Decibel Level (dBA)	73
Weight (in lbs)	48.000000
Feature	Spec
AHRI Certificate Number	7368845
Airflow Direction	Downflow/Horizontal
Exhaust Flue Requirement	Plastic / PVC
Product Features	Rebate Available
Furnace Efficiency / AFUE	96%
Blower Motor	Variable Speed - ECM
Maximum CFM	2000
Configuration	Upflow / Downflow
Energy Star	Yes
Burner Stages	Two
Fuel Type	Propane, Natural Gas
Height	30"
Width	24.5"
Depth	21"
Resources	CAPF Installation Manual CAPF 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.
SEER1 (Efficiency)	16
Condenser Stages	Single Stage
Compressor Type	Scroll
Liquid Valve Size	3/8"
Suction Valve Size	7/8"
Max Breaker Size	40 amps
Min. Breaker Size	23.5 amps
Tonnage	5 Ton
Liquid Line	3/8"
Suction Line	1 1/8"
Style	A-Coil
Suction Line Insulation Thickness	1/2"
Length	50 feet

Frequently Asked Questions

How does 15 SEER compare to newer air conditioners? +

15 SEER is solid but mid-tier. Newer 2024 models reach 16-17 SEER for similar costs. The difference translates to 6-10% annual cooling savings. For northern climates where cooling load is light, the gap matters less. In hot, humid regions, upgrade to 16+ SEER for better long-term ROI.

Can this downflow unit replace my existing upflow furnace? +

Yes, if you have attic ductwork or horizontal runs. Verify return air pathways and discharge plenum fit before ordering. The 30-inch height is designed for tight spaces, but your installer must confirm ductwork connections match existing infrastructure to avoid retrofit costs.

What does 96% AFUE actually save in annual heating costs? +

A 96% AFUE furnace saves roughly 15-20% on heating bills versus older 80% units, depending on climate and runtime. In Minnesota or upstate New York where furnace use exceeds 2000 hours annually, expect $200-400 yearly savings. Warmer climates see less savings due to shorter heating seasons.

Is Goodman reliable compared to Carrier or Lennox? +

Goodman holds its own on reliability. Field data shows similar compressor longevity to Carrier's entry lines. Lennox edges ahead in premium build quality but costs 30-50% more. For contractors managing service call patterns, Goodman parts availability and repair-friendly design is competitive.

Does the 10-year warranty cover labor and refrigerant? +

The warranty covers parts only. Labor and refrigerant charges are your responsibility. Many contractors bundle service plans for first-year support. Always register online immediately after installation to secure the full 10-year window.

Affiliate disclosure: IndustrialRank earns a commission on qualifying purchases at no extra cost to you. We only recommend products we have independently reviewed.