3 Ton 17 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 upgrading older equipment who want reliable dual-fuel flexibility and solid efficiency without premium pricing. The 96% AFUE furnace and 18 SEER2 air conditioner deliver meaningful energy savings, while the two-stage design on both heating and cooling provides better temperature control and quieter operation.

Review

This Goodman gas furnace and air conditioner system represents a solid mid-range option for contractors and homeowners seeking reliable performance without boutique pricing. The 3-ton downflow configuration works well in basements and attics where headroom is tight. Online Supply positions this as an Energy Star qualified alternative to legacy equipment, backed by a reasonable 10-year warranty. It's designed for residential comfort, not commercial use.

The heating side delivers 100,000 BTU at 96% AFUE using a two-stage burner and modulating operation. The cooling side produces 35,000 BTU (listed capacity, though tonnage specs conflict) with an 18 SEER2 two-stage scroll compressor using R410A refrigerant. The variable-speed ECM blower runs up to 2000 CFM, adjusting itself rather than cycling on-off. Operating noise sits at 71 dBA, typical for this class. Electrical requirements are straightforward, needing 208/230V single-phase 60 Hz with a 35 amp breaker.

Pros & Cons

Pros

96% AFUE furnace rating means you recover nearly all fuel energy as heat, reducing gas bills significantly
18 SEER2 cooling efficiency and two-stage condenser design provides quieter operation at 71 dBA and better humidity control
Variable-speed ECM blower motor adjusts to actual demand rather than cycling on-off, improving comfort and efficiency
Accepts both natural gas and propane, giving you fuel flexibility if you ever switch suppliers
Two-stage burner and compressor reduce runtime and noise compared to single-stage models
Energy Star certified system qualifies you for some utility rebates depending on your region

Cons

Cooling capacity listed as 35,000 BTU contradicts the 3-ton headline (should be 36,000 BTU), creating confusion about actual output
Specs show conflicting tonnage (3-ton in title but 5-ton in specs), indicating a documentation error you'll need clarified before purchase
71 dBA noise level is moderate, not quiet, so you'll hear it running especially during heating startup

Who Should Buy

Best For

Homeowners in areas with cold winters who heat with gas and cool with AC, especially those replacing 10+ year old equipment. You'll appreciate the dual-stage operation reducing energy costs and the flexibility to switch fuels if needed down the road.

Consider Alternatives If

Skip this unit if you need absolute silence (go inverter-driven instead) or if the contradictory tonnage specs (3-ton vs. 5-ton listing) concern you without clarification from the seller.

3 Ton 17 SEER 96% AFUE 100,000 BTU Goodman Gas Fur

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Installation

This unit arrives ready for standard split-system installation. The downflow/horizontal design requires proper return ductwork configuration and clear combustion air supply if in a closet. PVC venting meets modern code requirements and simplifies flue runs compared to old metal ductwork. You'll need adequate clearance for service access on all sides. Standard lineset (provided separately) uses 3/8 inch liquid and 7/8 inch suction lines with 3/4 inch insulation thickness.

Warranty & Reliability

Goodman includes a 10-year parts and labor warranty when you register online within 30 days of installation. This covers compressor, heat exchanger, and major components. Labor coverage is valuable if something fails mid-warranty. The evaporator coil carries separate coverage. Registration is non-negotiable, so do it immediately after startup to avoid losing protection.

Specifications

SKU	LS38783850
Brand/Manufacturer	Online Supply
Cooling BTU	35,000
Heating BTU	100,000
Refrigerant	R410A
Electrical	208 / 230 V. 1 Phase 60 Hz
Warranty	10 Years with Online Registration
Decibel Level (dBA)	71
Weight (in lbs)	30.000000
Feature	Spec
AHRI Certificate Number	7368844
Airflow Direction	Downflow/Horizontal
Exhaust Flue Requirement	Plastic / PVC
Product Features	Two Stage Condenser
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	21"
Depth	21"
Resources	CAPT Installation Manual CAPT 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)	18
Condenser Stages	Two Stage
Compressor Type	Scroll
Liquid Valve Size	3/8"
Suction Valve Size	3/4"
Max Breaker Size	35 amps
Min. Breaker Size	21.3 amps
Tonnage	5 Ton
Valve Type	Sweat
Liquid Line	3/8"
Suction Line	7/8"
Style	A-Coil
Suction Line Insulation Thickness	3/4"
Length	50 feet

Frequently Asked Questions

Why do the specs list both 3-ton and 5-ton ratings for this system? +

There's a documentation error in the product listing. The title claims 3-ton while the specs sheet shows 5-ton tonnage. Before purchasing, contact Online Supply for clarification, as this affects whether it matches your existing ductwork and capacity needs. Don't assume sizing until confirmed.

Can I install this unit in my attic with limited space? +

Yes, the downflow configuration is designed for attics and basement installations where headroom matters. The 30 inch height, 21 inch width and depth fit standard closet spaces. Ensure adequate return ductwork, proper combustion air, and venting clearance before finalizing installation location.

How much will this system reduce my heating and cooling bills compared to older equipment? +

The 96% AFUE furnace is roughly 10-15 percentage points better than equipment from 2005, and the 18 SEER2 cooling is 5-8 points better than units from 2010. Real savings depend on usage patterns, thermostat settings, and insulation. Budget 15-20% annual energy reductions as a realistic expectation.

How does this Goodman system compare to higher-end brands like Lennox or Carrier? +

Goodman delivers similar efficiency and reliability at lower upfront cost, though premium brands often have quieter units and longer warranties. This system is excellent value for budget-conscious buyers. You trade brand prestige for savings, but core performance is competitive at this efficiency level.

What happens if something breaks after year 10 with the warranty expired? +

Parts and labor coverage ends after 10 years. Repairs become your responsibility. Goodman equipment typically runs 15-18 years with maintenance, so budget for possible repairs after warranty expires. Extended warranty plans may be available at purchase.

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