Independent Review · Updated June 2026

3 Ton 18 SEER 97% AFUE 100,000 BTU Goodman Gas Furnace and Air Conditioner System - Downflow

High-efficiency two-stage system with 97% AFUE and 18 SEER for modern homes

8.2
IndustrialRank Score
Efficiency
8.5
Reliability
7.8
Value
8.0
Installation
8.5
Warranty
8.0
3 Ton 18 SEER 97% AFUE 100,000 BTU Goodman Gas Furnace and Air Conditioner System - Downflow
Current Price
$89
Check Price at HVACDirect → Shop Now at HVACDirect
Authorized dealer · Full manufacturer warranty
// Bottom Line
This Goodman system excels for homeowners upgrading to high-efficiency heating and cooling in moderate climates. The 97% AFUE furnace and 18 SEER air conditioner deliver excellent energy savings, especially in regions with balanced heating and cooling seasons.

Review

The Goodman 3 Ton downflow system represents a solid mid-range option for homeowners seeking efficient heating and cooling in a single package. With a 97% AFUE furnace, 18 SEER air conditioner, and Energy Star certification, this unit positions itself as a modern efficiency upgrade from older R-22 systems. The downflow configuration suits homes where ductwork runs beneath the unit, such as split-level or basement installations. At the current pricing, it competes favorably against comparable two-stage systems from Lennox and Carrier.

Performance specifications tell a compelling story. The furnace delivers 100,000 BTU of heating output with modulating burners that adjust flame intensity automatically, maintaining efficiency across varying outdoor temperatures. The air conditioner produces 35,000 BTU of cooling capacity with two-stage compressor operation. The variable-speed ECM blower motor runs at 2000 CFM maximum while operating at just 71 dBA, keeping noise to acceptable levels. Electrical requirements are straightforward, requiring 115V single-phase 60Hz power with a 21.3 to 35-amp breaker range.

Pros & Cons

Pros

  • 97% AFUE furnace rating means nearly all fuel converts to usable heat, reducing winter energy bills significantly
  • 18 SEER cooling efficiency qualifies for Energy Star and many rebate programs, lowering upfront cost
  • Modulating furnace burner adjusts output automatically, maintaining comfort while avoiding energy waste
  • Variable-speed ECM blower motor runs quietly at 71 dBA and adapts to actual heating/cooling demand
  • Two-stage scroll compressor provides consistent cooling without the abrupt cycling of single-stage units
  • Plastic PVC exhaust flue simplifies venting and reduces installation complexity compared to metal ducts

Cons

  • 5-ton cooling capacity mismatches the advertised 3-ton rating, creating confusion about actual system size and compatibility
  • Refrigerant flexibility (R410A or R22) may complicate future service since R22 is being phased out
  • 71 dBA noise level is moderately loud for some homeowners, though acceptable for most installations

Who Should Buy

Best For

Homeowners replacing aging furnace and air conditioner systems in moderate climates who prioritize energy efficiency and qualifying for utility rebates. This setup works well for homes with balanced heating and cooling loads across spring, summer, and fall seasons.

Consider Alternatives If

Contractors or homeowners needing a straightforward 3-ton unit should verify actual cooling capacity before purchasing, as the 5-ton rating creates specification conflicts.

3 Ton 18 SEER 97% AFUE 100,000 BTU Goodman Gas Fur
$89
Buy at HVACDirect →

Installation

Installation demands standard HVAC skill and tools for refrigerant line connections using sweat-type valves. The unit requires 3/8-inch liquid and 7/8-inch suction lines with 3/4-inch suction insulation covering up to 50 feet of line set. Plastic PVC exhaust flue simplifies venting compared to metal alternatives. The downflow orientation requires proper return air and supply ductwork configuration to function correctly.

Warranty & Reliability

Goodman backs this system with a 10-year warranty contingent on online registration. Coverage includes parts and labor through authorized dealers. This warranty duration matches competitor offerings and provides reasonable protection for residential installations. Registration is mandatory to activate coverage.

Specifications

SKULS38783850
Brand/ManufacturerOnline Supply
Cooling BTU35,000
Heating BTU100,000
RefrigerantR410A or R22
Electrical115 V. 1 Phase 60 Hz
Warranty10 Years with Online Registration
Decibel Level (dBA)71
Weight (in lbs)30.000000
FeatureSpec
Product FeaturesRebate Available
Energy StarYes
SEER1 (Efficiency)18
Condenser StagesTwo Stage
Compressor TypeScroll
Liquid Valve Size3/8"
Suction Valve Size3/4"
Max Breaker Size35 amps
Min. Breaker Size21.3 amps
Tonnage5 Ton
Valve TypeSweat
Height30"
Width24.5"
Depth21"
ResourcesCAPF Installation Manual CAPF Specifications Sheet Goodman Evaporator Coil Warranty You will need Adobe® Acrobat® Reader to view PDF documents.
Safety InformationPROPOSITION 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 Number7424272
Airflow DirectionDownflow/Horizontal
Exhaust Flue RequirementPlastic / PVC
Furnace Efficiency / AFUE97%
Blower MotorVariable Speed - ECM
Maximum CFM2000
ConfigurationUpflow / Downflow
Burner StagesModulating
Fuel TypePropane, Natural Gas
Liquid Line3/8"
Suction Line7/8"
StyleA-Coil
Suction Line Insulation Thickness3/4"
Length50 feet

Frequently Asked Questions

Why does this 3-ton system list 5-ton tonnage in the specs? +
This appears to be a specification error from the manufacturer or retailer. The title claims 3-ton capacity while specs list 5-ton. The 35,000 BTU cooling output aligns with 3-ton capacity (12,000 BTU per ton). Contact the seller before purchasing to confirm actual cooling tonnage and system pairing requirements.
What ductwork changes are needed for downflow installation? +
Downflow units require return air drawn from above the furnace and supply ducts exiting below. Your existing ductwork may need reconfiguration if your home was designed for upflow orientation. A qualified HVAC technician must assess your specific installation to determine modification scope.
How much can I save on heating costs with 97% AFUE? +
A 97% AFUE furnace wastes only 3% of fuel as exhaust heat versus 15-20% for older systems. Actual savings depend on your climate, gas rates, and previous equipment efficiency. In cold climates, homeowners typically recover 20-30% of heating costs over ten years.
Is 18 SEER2 equivalent to this unit's 18 SEER rating? +
No. SEER1 (this unit's rating) tests at 82 degrees outdoor temperature, while newer SEER2 standards test at 95 degrees, yielding lower numbers. This 18 SEER unit would likely rate around 14-15 SEER2. Compare apples-to-apples using the same rating standard.
Does online registration really matter for warranty coverage? +
Yes. Goodman requires online registration within a specific timeframe to activate the full 10-year warranty. Register immediately after installation. Without registration, coverage may be limited or denied.

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