🏠 Introduction: From Research to Reality
When I decided to install my own Goodman 3 Ton 15.2 SEER2 R-32 Dual-Fuel System, I knew it wasn’t a small weekend project. I’m a hands-on homeowner, not a certified HVAC technician — but I’ve learned a lot through years of maintenance, small installs, and countless hours of reading manufacturer manuals.
This guide isn’t a replacement for a licensed professional — especially when it comes to gas connections or refrigerant handling — but it’s the kind of practical, real-world roadmap I wish I’d had when starting out.
The Goodman dual-fuel system combines an R-32 air conditioner condenser, a matching vertical evaporator coil, and a 96% AFUE 100,000 BTU natural gas furnace. It’s an energy-efficient, comfort-balanced powerhouse — but getting it installed correctly takes careful planning, patience, and the right tools.
⚙️ 1. Understanding the System Before You Begin
🔍 What “Dual-Fuel” Really Means
A dual-fuel system pairs an electric heat pump or air conditioner with a gas furnace, allowing your home to automatically switch between electric cooling and gas heating depending on outdoor temperature and efficiency needs.
This Goodman setup uses R-32 refrigerant, known for higher efficiency and lower global warming potential (GWP) compared to R-410A.
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AC/Condenser Model: GLXS4BA3610
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Coil Model: CAPTA3626C3 (Vertical)
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Gas Furnace Model: GR9T961005CN
Each component works together seamlessly — but only if you match airflow, refrigerant line size, and electrical load properly.
🧮 Sizing Check
Before you even think about cutting or connecting anything, confirm that your 3-ton capacity (36,000 BTU) system matches your home’s needs. Oversized systems short-cycle and waste energy, while undersized ones run constantly.
👉 Use an online load calculator like Energy Vanguard’s Manual J resource or have an HVAC pro run a Manual J heat load analysis to double-check.
📦 2. Preparing for Installation
🧰 Tools & Materials Checklist
Here’s what I gathered before starting:
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Adjustable wrenches & socket set
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Drill & hole saw
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¾" PVC pipe (for condensate drain)
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Sheet metal screws & foil tape
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Level & measuring tape
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Electrical conduit, wire nuts, and disconnect box
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Refrigerant line set (R-32 compatible)
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Vacuum pump & micron gauge
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Torque wrench
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Nitrogen tank (for pressure testing)
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Pipe dope or thread sealant for gas lines
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Digital multimeter
You’ll also need PPE — gloves, safety glasses, and hearing protection.
📍 Site Prep: Location & Clearance
I chose a shaded area on the north side of my home for the condenser, ensuring:
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Minimum 12 inches of clearance on all sides
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5 feet above for airflow
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Solid, level concrete or composite pad
Inside, the furnace and coil sit in a dedicated utility closet with:
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24" front service clearance
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Proper return and supply duct sizing
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Adequate combustion air (verified via local building code)
🧩 3. Step-by-Step: Installing the Furnace and Coil
🔧 Step 1: Setting the Furnace in Place
I started with the GR9T961005CN gas furnace — the heaviest component. Position it so the front panel faces outward for service access.
Check for:
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Level placement (use shims if needed)
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Return air duct alignment
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Flue vent direction (upflow or horizontal)
Then, attach the vertical coil (CAPTA3626C3) on top using foil tape and self-tapping screws to create an airtight seal.
🔥 Step 2: Connecting Gas Lines (with Caution)
Gas connections are one of the few steps I always recommend leaving to a licensed plumber or HVAC tech. Incorrect installation can cause leaks, fire, or carbon monoxide hazards.
Still, here’s what I observed during my install:
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Black iron gas line connected via flexible stainless connector
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Thread sealant used only on male iron pipe threads
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Leak testing performed using soap solution before ignition
🌀 Step 3: Drain Line and Coil Connections
I connected a ¾" PVC drain line to the coil’s primary outlet, ensuring a 1/4" per foot downward slope.
Add a P-trap to prevent negative pressure from drawing air into the drain.
Pro tip: Test by pouring water through before sealing everything.
⚡ 4. Wiring & Electrical Connections
🔌 Step 1: Power Supply and Breakers
This Goodman system runs on 240V for the condenser and 120V for the furnace blower.
I ran a dedicated 30A circuit for the condenser and a 15A for the furnace.
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Install a weatherproof disconnect box near the outdoor unit
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Route metallic conduit to protect wiring
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Bond the system to the house ground
🔗 Reference: National Electrical Code (NEC) Article 440 – HVAC Equipment
🧠 Step 2: Thermostat Wiring
My dual-fuel setup uses a 7-wire connection to a smart thermostat (Honeywell T10 Pro).
Here’s the basic layout:
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R – 24V Power
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C – Common
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Y/Y2 – Compressor stages
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G – Blower fan
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W/W2 – Gas furnace
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O/B – Reversing valve (for heat pump, if equipped)
Always label wires before removal — trust me, future you will thank you.
❄️ 5. Installing the Outdoor R-32 Condenser
🧱 Step 1: Set the Pad and Mount the Unit
The GLXS4BA3610 condenser sits on a vibration-isolated pad.
Make sure it’s perfectly level and elevated above grade to prevent flooding during heavy rain.
Secure with anti-vibration brackets if local code requires.
🔗 Step 2: Line Set Connections (Refrigerant Piping)
Use R-32 rated copper lines — usually 3/8” liquid and 3/4” suction for a 3-ton unit.
Run lines carefully through an exterior wall sleeve to prevent kinking.
Before tightening:
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Purge with nitrogen to avoid oxidation
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Torque flare fittings per Goodman specs
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Perform pressure test (250–300 psi nitrogen) for leaks
🌬️ Step 3: Evacuation and Charging
With the lines sealed and tested:
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Connect a vacuum pump to pull down to 500 microns.
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Close valves and verify pressure holds steady (no leaks).
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Release the factory pre-charged R-32 refrigerant into the system.
R-32 has a higher operating pressure than R-410A, so always follow manufacturer charge tables.
⚠️ Important: Only EPA Section 608-certified techs can legally handle refrigerant. As a DIYer, I supervised this step with a licensed technician.
🔗 Reference: EPA Section 608 Refrigerant Regulations
🔥 6. Startup and Testing
After wiring and refrigerant charging were complete, it was time for system testing.
🧭 Step 1: Verify Airflow
Use a simple anemometer at supply vents or check static pressure with a manometer.
Typical static pressure for most Goodman systems should be 0.5–0.8 inches WC.
If pressure’s too high:
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Check for dirty filters or undersized ducts.
If too low: -
Inspect for duct leaks or disconnected boots.
🔗 Resource: Energy.gov Duct Sealing Guide
🌡️ Step 2: Check Temperature Split
Run cooling mode for 15 minutes, then measure:
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Return air temp: e.g., 78°F
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Supply air temp: e.g., 58°F
→ 20°F temperature split = ideal performance
🔥 Step 3: Furnace Heating Test
Switch to heating mode. The gas furnace should:
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Ignite smoothly
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Reach steady flame with no noise
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Exhaust through PVC vent without leaks
If you smell gas or see yellow flames, shut off immediately and call a pro.
🧽 7. Post-Install Finishing Touches
🧾 Label Everything
Label electrical breakers, disconnects, and thermostat wires.
Future maintenance (or resale) will be much easier.
🧊 Insulate the Line Set
Wrap the suction line with UV-rated insulation.
For outdoor runs, seal joints with weather-resistant tape.
🧯 Install a Surge Protector
A small investment that protects compressors and control boards from power surges.
🧼 8. Maintenance Tips After Installation
A successful installation is just the beginning.
To keep your Goodman R-32 system performing efficiently, I follow this simple routine:
| Season | Maintenance Task | Why It Matters |
|---|---|---|
| Spring | Clean condenser coils, test cooling mode | Prevents high head pressure |
| Summer | Replace filters monthly | Maintains airflow |
| Fall | Flush condensate drain, inspect gas venting | Preps for heating |
| Winter | Check furnace flame sensor | Ensures safe combustion |
💡 9. Common Mistakes I Almost Made (and How to Avoid Them)
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Skipping the nitrogen purge — causes black carbon flakes inside coils.
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Forgetting to trap the condensate line — leads to water backup.
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Using old thermostat wire — mine had brittle insulation that caused a short.
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Not sealing duct joints properly — wasted airflow and added noise.
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Improper coil orientation — caused refrigerant oil pooling until corrected.
Learning these lessons the hard way reminded me that small oversights can have big consequences.
🧠 10. Final Thoughts: What I’d Tell Any Homeowner
Installing a Goodman 3 Ton R-32 Dual-Fuel System is absolutely doable for a capable homeowner — with respect for safety, code compliance, and professional limits.
Here’s my biggest takeaway:
“Do as much as you safely can — and know when to call in help.”
I handled the prep, wiring, ducting, and drainwork confidently. But for refrigerant charging and gas hookup, I partnered with a certified pro. That’s what makes this a smart DIY, not a reckless one.
In the next topic we will know more about: SEER2 Explained: The Impact of Efficiency on Your Utility Costs
