3 Ton 17 SEER 97% AFUE 100,000 BTU Goodman Gas Furnace and Air Conditioner System - Downflow Review 2026

// Bottom Line

This Goodman system is ideal for homeowners upgrading from older equipment or contractors building cost-effective installations in moderate climates. The 97% AFUE furnace and SEER 18 cooling deliver genuine efficiency gains without premium pricing, making it excellent for budget-conscious buyers willing to accept a value brand.

Review

The Goodman 3-ton gas furnace and air conditioner system represents the practical middle ground in residential HVAC. At $736, this downflow combo delivers 97% AFUE heating efficiency and 18 SEER cooling in a compact 38.25-inch tall footprint designed for tight installation spaces. It's an unadorned, spec-focused package that skips luxury features but includes the efficiency standards modern homes demand, making it a straightforward value proposition for upgrade-minded homeowners.

Performance numbers tell the real story here. The 100,000 BTU heating capacity with modulating burner technology adjusts output based on actual demand, reducing runtime waste. The 35,000 BTU cooling capacity operates at 18 SEER efficiency using R410A refrigerant with a scroll compressor and two-stage condenser. Variable-speed ECM blower motor runs at 2,000 CFM maximum, operating at 71 dB noise level. Energy Star certification confirms real-world efficiency, not inflated lab ratings. This combination avoids the worst inefficiencies of older single-stage equipment without premium pricing.

Pros & Cons

Pros

97% AFUE furnace efficiency with modulating burner reduces heating costs significantly compared to 80-90% older units
18 SEER cooling rating meets modern efficiency standards, qualifying for Energy Star and many utility rebates
Modulating gas burner and variable-speed ECM blower motor provide comfort and quieter operation versus single-stage alternatives
Downflow A-coil design fits tight attic and closet spaces where traditional cabinets won't work
$736 price point is 25-35% below comparable Carrier and Lennox units with similar specs
PVC exhaust compatibility simplifies installations in modern homes with plastic flue venting

Cons

Goodman brand carries lower brand perception than Carrier or Lennox, though performance is solid
Two-stage cooling may short-cycle in very mild climates, reducing efficiency below rated SEER 18
71 dB noise level is moderately loud for night operation compared to high-end inverter compressor units
35,000 BTU cooling capacity is undersized for homes larger than 1,500 square feet in hot climates

Who Should Buy

Best For

Homeowners replacing 15+ year old equipment who want measurable efficiency gains without brand prestige pricing, and contractors installing systems for price-sensitive residential clients in mild to moderate climates. This system delivers real performance improvements where they matter most, heating and cooling efficiency.

Consider Alternatives If

Anyone seeking premium reliability features, those in extremely hot climates requiring oversized cooling capacity, or buyers who prioritize brand name and dealer support over actual efficiency specifications.

3 Ton 17 SEER 97% AFUE 100,000 BTU Goodman Gas Fur

$736

Buy at HVACDirect →

Installation

Downflow configuration requires clear vertical space above the furnace for airflow return and below for supply ducting. PVC exhaust venting needs outdoor termination with proper slope to prevent condensation backup. Connection points require 3/8-inch liquid and 7/8-inch suction line sizing for the R410A charge. Electrical demands 208/230V single-phase power with 21.9 to 35-amp breaker capacity. Most HVAC contractors complete installation in one day for straightforward replacements.

Warranty & Reliability

Goodman includes a 10-year parts warranty activated through online registration, a reasonable duration for equipment in this price tier. Registration is mandatory, not automatic, so homeowners must complete this within 30 days of purchase. The warranty covers compressor, heat exchanger, and control boards. Extended plans are available separately. This standard coverage aligns with value-brand expectations but trails premium brands offering 12-15 year terms.

Specifications

SKU	TX3N4
Brand/Manufacturer	Goodman
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)	2.500000
Feature	Spec
Configuration	Downflow/Horizontal
Liquid Line	3/8"
Suction Line	7/8"
Tonnage	3 Ton
Style	A-Coil
Height	38.25"
Width	35.5"
Depth	35.5"
Resources	Goodman Specifications Goodman Installation Manual 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.
AHRI Certificate Number	7424272
Airflow Direction	Downflow/Horizontal
Exhaust Flue Requirement	Plastic / PVC
Product Features	Rebate Available
Furnace Efficiency / AFUE	97%
Blower Motor	Variable Speed - ECM
Maximum CFM	2000
Energy Star	Yes
Burner Stages	Modulating
Fuel Type	Propane, Natural Gas
SEER1 (Efficiency)	18
Condenser Stages	Two Stage
Compressor Type	Scroll
Liquid Valve Size	3/8"
Suction Valve Size	7/8"
Max Breaker Size	35 amps
Min. Breaker Size	21.9 amps
Valve Type	Sweat

Frequently Asked Questions

Is this system truly 18 SEER, or is that inflated rating? +

The 18 SEER1 rating is legitimate under current testing standards, though real-world performance varies by installation quality, ductwork efficiency, and climate. You'll see genuine utility bill reductions versus 13-14 SEER older systems, typically 15-20% annual savings in moderate climates. Hot climates with heavy cooling demands show larger percentage gains.

Can this downflow unit fit in my attic space? +

At 38.25 inches tall and 35.5-inch square footprint, it fits most attics with 4+ feet clearance. Downflow design means return air pulls from above, supply air exits below. Ensure PVC exhaust pipe can route vertically or horizontally to outdoor termination. Measure existing space carefully before ordering.

How much should I expect to save on heating costs annually? +

A 97% AFUE furnace versus typical 80-85% older unit saves approximately 12-17% annual heating costs for equivalent comfort. In cold climates with $2,000 annual heating bills, expect $240-340 yearly savings. Payback typically occurs within 8-10 years through fuel savings alone, before cooling efficiency gains.

How does this compare to Carrier or Lennox units at the same 3-ton capacity? +

Carrier and Lennox 3-ton systems with similar 97% AFUE and 18 SEER ratings cost $1,200-1,600 installed. Goodman delivers identical performance specs at 40-50% lower material cost. The trade-off is Goodman's smaller dealer network and lower resale value perception, not performance differences.

Is online registration required for the warranty to be valid? +

Yes, the 10-year warranty requires online registration within 30 days of installation. Without registration, coverage defaults to a limited 5-year parts warranty. Register immediately after installation to protect your investment fully.

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