Independent Review · Updated June 2026

3.5 Ton 15 SEER 97% AFUE 80,000 BTU Goodman Gas Furnace and Air Conditioner System - Downflow

High-efficiency modulating furnace with 97% AFUE and variable-speed blower for tight control.

8.2
IndustrialRank Score
Efficiency
8.5
Reliability
7.8
Value
8.0
Installation
8.5
Warranty
8.0
3.5 Ton 15 SEER 97% AFUE 80,000 BTU Goodman Gas Furnace and Air Conditioner System - Downflow
Current Price
$0
Check Price at HVACDirect → Shop Now at HVACDirect
Authorized dealer · Full manufacturer warranty
// Bottom Line
This Goodman system is ideal for contractors seeking a dependable, efficient furnace that doesn't break the budget while delivering genuine comfort improvements. The 97% AFUE rating and modulating burner make it particularly strong for homeowners in cold climates who want lower heating bills without premium pricing.

Review

The Goodman 3.5-ton downflow furnace with air conditioner system represents a solid middle-ground choice for contractors and homeowners seeking efficiency without premium pricing. Branded through Online Supply and certified under AHRI #7424271, this unit emphasizes modulating heating and variable-speed blower technology. At 97% AFUE and ENERGY STAR certified, it competes respectably against mid-tier alternatives while maintaining familiar Goodman reliability and serviceability in the field.

Performance metrics show a 97% AFUE furnace with 80,000 BTU heating output paired to a 42,000 BTU cooling section (SEER 16). The modulating burner stages fuel input to match demand, while the ECM variable-speed blower optimizes CFM from 0 to 1,600. Sound output reaches 73 dBA at rated capacity. Refrigerant options include R410A or R22, with 3/8 inch liquid and 1 1/8 inch suction lines over 50 feet maximum length.

Pros & Cons

Pros

  • 97% AFUE furnace efficiency means minimal heat waste compared to standard 80-85% units
  • Modulating burner automatically adjusts heat output to match demand, reducing short-cycling and improving comfort
  • Variable-speed ECM blower can scale airflow between 0 and 1,600 CFM, lowering electrical draw during partial load operation
  • PVC exhaust compatibility simplifies venting in retrofit applications and reduces installation cost
  • 10-year warranty with online registration provides solid protection for both parts and labor

Cons

  • SEER rating spec shows conflicting data: title claims 15 SEER but specs list 16 SEER1, creating confusion about actual cooling efficiency
  • Single-stage condenser means the outdoor unit doesn't modulate, limiting part-load cooling efficiency and comfort in shoulder seasons
  • Tonnage mismatch exists: furnace delivers 80,000 BTU (6.7 tons) while system is marketed as 3.5-ton with 42,000 BTU cooling capacity

Who Should Buy

Best For

Contractors building new systems in cold climates or replacing furnaces in existing homes where PVC venting is feasible. Homeowners in gas service areas who prioritize heating efficiency and want measurable energy savings without spending on high-end two-stage equipment.

Consider Alternatives If

Anyone needing balanced cooling capacity should look elsewhere, since this 3.5-ton system pairs unequal heating and cooling BTU output. Those in very humid climates benefit more from two-stage condensers.

3.5 Ton 15 SEER 97% AFUE 80,000 BTU Goodman Gas Fu
$0
Buy at HVACDirect →

Installation

This downflow unit measures 30 inches tall by 21 inches wide and deep, fitting standard mechanical closets and attic spaces. PVC exhaust flue requirement simplifies venting through exterior walls. Right-side flue outlet allows flexible ductwork routing. Electrical demand runs 208/230V single-phase 60Hz with 23.5 to 40 amp breaker sizing. Variable-speed blower integration requires compatible thermostat or control module for full modulation capability.

Warranty & Reliability

Goodman covers this system for 10 years on parts and labor when registered online within 30 days of installation. Compressor and evaporator coil receive additional coverage under Goodman's extended warranty program. Registration is straightforward but required to activate full protection, so contractors should confirm homeowner completion before final billing.

Specifications

SKULS381183850
Brand/ManufacturerOnline Supply
Cooling BTU42,000
Heating BTU80,000
RefrigerantR410A or R22
Electrical208 / 230 V. 1 Phase 60 Hz
Warranty10 Years with Online Registration
Decibel Level (dBA)73
Weight (in lbs)48.000000
FeatureSpec
AHRI Certificate Number7424271
Airflow DirectionDownflow/Horizontal
Exhaust Flue RequirementPlastic / PVC
Product FeaturesRebate Available
Furnace Efficiency / AFUE97%
Blower MotorVariable Speed - ECM
Maximum CFM1600
ConfigurationUpflow / Downflow
Flue LocationRight
Energy StarYes
Burner StagesModulating
Fuel TypePropane, Natural Gas
Height30"
Width21"
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.
SEER1 (Efficiency)16
Condenser StagesSingle Stage
Compressor TypeScroll
Liquid Valve Size3/8"
Suction Valve Size7/8"
Max Breaker Size40 amps
Min. Breaker Size23.5 amps
Tonnage5 Ton
Liquid Line3/8"
Suction Line1 1/8"
StyleA-Coil
Suction Line Insulation Thickness1/2"
Length50 feet

Frequently Asked Questions

Does this 3.5-ton system provide balanced heating and cooling capacity? +
No. The 80,000 BTU furnace equals roughly 6.7 tons heating, while the condenser delivers only 42,000 BTU (3.5 tons) cooling. This mismatch means oversized heating relative to cooling, which is typical for cold climates but limits shoulder-season comfort. Verify BTU balance with the system designer before ordering.
What thermostat or control is needed to use the variable-speed ECM blower? +
The ECM motor can operate in standard on/off mode with any thermostat, but true modulation requires a compatible control module or communicating thermostat. Check compatibility with your chosen thermostat brand before installation. Goodman and most quality units offer integration, but confirmation prevents field issues.
How much heating efficiency gain does 97% AFUE deliver compared to standard furnaces? +
A standard 80% AFUE furnace wastes 20 cents per dollar as flue loss. At 97% AFUE, waste drops to 3 cents. Over a heating season, this translates to roughly 15-20% lower gas consumption in cold climates. Actual savings depend on thermostat settings and local utility rates.
Can this furnace run on propane or only natural gas? +
The unit supports both propane and natural gas operation. Orifice and regulator adjustments at installation determine fuel type. Confirm your local fuel supply and ensure the contractor orders the correct conversion kit if switching from your existing fuel source.
Is online registration required to activate the 10-year warranty? +
Yes. The warranty requires online registration within 30 days of installation. Without registration, coverage defaults to a shorter term. Contractors should handle registration immediately after startup to protect the homeowner and prevent future disputes.

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