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 is ideal for homeowners replacing older equipment in moderate to large homes needing both heating and cooling upgrades. At $3136, it delivers genuine high-efficiency performance with Energy Star certification and a strong 96% AFUE rating for natural gas or propane furnaces.

Review

This Goodman gas furnace and air conditioner combo targets the mid-market segment where homeowners need dependable climate control without flagship-brand premiums. The 120,000 BTU furnace pairs with 42,000 BTU cooling capacity in a compact downflow unit designed for basement or closet installations. Online Supply's $3136 price point sits well below premium manufacturers, yet Energy Star certification signals serious efficiency engineering beneath the budget-friendly positioning.

The 96% AFUE rating means virtually all fuel converts to usable heat, a meaningful jump from the 80-85% AFUE units still common in older homes. Cooling delivers 16 SEER1 performance via a scroll compressor and A-coil configuration with R410A or R22 refrigerant compatibility. The variable-speed ECM blower motor, running at up to 2000 CFM, adjusts automatically to load conditions, reducing runtime noise and improving indoor humidity control compared to constant-speed alternatives.

Pros & Cons

Pros

96% AFUE furnace efficiency means lower heating bills compared to 80-90% models, saving approximately $15-25 monthly in cold climates
16 SEER1 air conditioning exceeds the 15 SEER stated in title, delivering Energy Star certified cooling performance
Variable-speed ECM blower motor provides quiet operation and better humidity control than single-speed alternatives
Compact 30-inch height suits downflow/horizontal installations where space is limited in basements or attics
Two-stage burner automatically adjusts heating output, reducing short-cycling and improving comfort during mild weather

Cons

Single-stage air conditioner cannot modulate cooling capacity, cycling on and off rather than ramping down on milder days
73 dB noise level is moderately loud, comparable to a dishwasher running, though variable-speed blower helps minimize cycling noise
Specification discrepancies between title and data sheet, 3.5 versus 5 ton tonnage, create confusion about actual system capacity

Who Should Buy

Best For

Homeowners upgrading from 10-15 year old split systems who want reliable, efficient heating and cooling without premium pricing. Contractors serving residential retrofit projects where building layout favors downflow configuration and variable-speed operation is valued.

Consider Alternatives If

Buyers needing single-zone zoning capability or those prioritizing ultra-quiet operation should explore variable-capacity compressor systems with lower decibel ratings.

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

$3136

Buy at HVACDirect →

Installation

Downflow configuration requires vertical ductwork below the unit, common in basement or mechanical closet setups. The 48-pound weight and 30-inch height fit standard framing. Installation demands 115V single-phase 60Hz power with 23.5 to 40-amp breaker capacity. PVC plastic exhaust flue piping, rather than metal venting, simplifies installation and reduces condensation issues in modern, tightly sealed homes.

Warranty & Reliability

Goodman includes a 10-year parts warranty with online registration, covering compressor and major components. This is standard industry coverage, not extended or lifetime protection. Registration is straightforward through Goodman's website and typically takes minutes. Evaporator coil coverage is included. Parts availability through Online Supply and authorized distributors is reliable for warranty claims.

Specifications

SKU	LS381183850
Brand/Manufacturer	Online Supply
Cooling BTU	42,000
Heating BTU	120,000
Refrigerant	R410A or R22
Electrical	115 V. 1 Phase 60 Hz
Warranty	10 Years with Online Registration
Decibel Level (dBA)	73
Weight (in lbs)	48.000000
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	40 amps
Min. Breaker Size	23.5 amps
Tonnage	5 Ton
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.
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
Burner Stages	Two
Fuel Type	Propane, Natural Gas
Liquid Line	3/8"
Suction Line	1 1/8"
Style	A-Coil
Suction Line Insulation Thickness	1/2"
Length	50 feet

Frequently Asked Questions

Is this system truly 3.5 ton or 5 ton capacity? +

Specifications list 5-ton tonnage with 42,000 BTU cooling output, which technically rates as 3.5 ton. The title overstates the heating tonnage. Confirm actual tonnage with Online Supply before purchase, as cooling capacity determines true system size for most applications.

Can this furnace run on both natural gas and propane? +

Yes, the specs confirm dual fuel compatibility with propane or natural gas. However, units are typically configured for one fuel at manufacturing. Verify your unit's fuel setting before installation, and confirm your local supply availability. Conversion between fuels requires professional adjustment.

How much will the 96% AFUE actually save compared to my old furnace? +

An 80% AFUE furnace wastes 20% of fuel; this 96% unit wastes only 4%. For homes burning 1000 therms annually, annual savings reach approximately $160-200 depending on gas rates. Payback typically occurs within 5-7 years through energy bill reduction.

Is 73 dB noise level acceptable for residential use? +

73 dB equals a dishwasher cycle, noticeable but not intrusive in basements or mechanical closets. Variable-speed blower reduces cycling noise compared to single-speed units. If the unit sits near bedrooms or living spaces, consider sound insulation or vibration dampening installation techniques.

What does the 10-year warranty actually cover? +

The warranty covers parts failure including compressor, heat exchanger, and coil defects when registered. Labor is not included. You pay service calls and installation of replacement parts. Standard manufacturer coverage, though some retailers offer extended labor plans separately.

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