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🛠️ Installation Guide: Mike’s Step-by-Step Walkthrough for His 3 Ton Horizontal Goodman AC

🧰 Introduction — Why I Wrote This Guide

I’m Mike, and I’ve been through more HVAC installs than I care to admit. When my old R-410A system started struggling in 2024, I knew I needed to upgrade before another sweltering summer hit.

The big decision? I went with a 3 Ton Goodman Horizontal AC using R-32 refrigerant. It wasn’t just about swapping equipment — it was about future-proofing, cutting bills, and setting up a system I could trust for the next 15–20 years.

While refrigerant handling and electrical hookups must be done by licensed pros, there’s still a ton of work a homeowner can do to prepare and support the install. That’s what this guide is about: my step-by-step process from planning to post-install maintenance.

📏 1. Pre-Installation Planning

Good installs don’t start with a wrench. They start with a notepad.

📐 1.1 Confirming the Load Size

I didn’t guess that 3 tons was right — I ran the numbers.

Rule of thumb: 1 ton ≈ 450–600 sq. ft. (LearnMetrics)
My home: 1,650 sq. ft. × 9 ft ceilings = ~36,000 BTUs.
Verified with an online Manual J tool (RemodelingCalculator ).

👉 Pro tip: Don’t rely on square footage alone. Factor in insulation, windows, duct losses, and climate zone.

📋 1.2 Permits and Inspections

HVAC isn’t plug-and-play. My county required:

Mechanical permit before starting.
Electrical permit for the 240V line.
Final inspection to confirm A2L refrigerant compliance.

I pulled permits early, so there were no delays once the system was ready.

📍 1.3 Choosing Horizontal

Why horizontal?

My attic ceiling is too low for a vertical air handler.
Horizontal units make duct branching easier in tight spaces.
Goodman offers dedicated horizontal R-32 models designed for attic installs.

Comparison of horizontal vs vertical installs: Larson Air.

🧱 2. Preparing the Site

Prep work is where I saved money and headaches.

🔨 2.1 Clearing & Reinforcing

Removed the old air handler and vacuumed up years of dust.
Built a new ¾” plywood platform, reinforced with joist bracing.
Added rubber vibration pads to reduce noise transfer.

👉 Lesson learned: My old platform sagged, which caused drainage issues. This time, I made it bulletproof.

🛑 2.2 Safety First

Shut off the breaker to the old unit.
Checked for live voltage with a multimeter.
Wore gloves, safety glasses, and a mask (fibreglass dust in attic = misery).

🌬️ 2.3 Ventilation

My attic hits 120–140°F in summer. To help both me and the AC, I:

Installed a solar-powered gable fan.
Added extra soffit vents for intake.

Cooler attic = better working conditions and higher system efficiency.

📦 3. Unboxing the Goodman Horizontal Unit

📦 3.1 What Came in the Box

Outdoor condenser (factory-charged with R-32).
Horizontal air handler with coil.
Thermostat (optional upgrade).
Installation manual, safety labels, and warranty packet.

📑 3.2 Double-Checking Specs

Always check model numbers. Mine: Goodman GPCH33631.

Capacity: 36,000 BTU (3 ton).
Refrigerant: R-32.
Voltage: 208/230V, single phase.
Orientation: Horizontal.

Link: The Furnace Outlet product page.

🔧 4. Installation Steps

Here’s where the rubber meets the road.

🏗️ Step 1: Platform & Levelling

Placed the air handler on a reinforced platform.
Checked level with torpedo level — critical for condensate drainage.

👉 Even a ¼” tilt can cause water pooling and overflow.

🌡️ Step 2: Ductwork

Connected the supply plenum to the main trunk.
Sealed seams with foil tape + mastic (never duct tape).
Insulated exposed ducts with R-8 wrap.

Resource: Energy.gov – Duct Sealing.

💧 Step 3: Condensate Drain

Installed primary drain line with ¼” per foot slope.
Added secondary (emergency) pan with float switch.
Tested by pouring a gallon of water through — no leaks.

👉 In humid climates, clogged drains = #1 cause of service calls.

⚡ Step 4: Electrical Work

Ran a new 240V line to a disconnect box near the condenser.
Bonded air handler ground to panel.
Verified breaker: 40A double pole.

👉 ⚠️ Licensed electrician only. I handled conduit runs but left terminations to a pro.

Code basics: NEC HVAC Electrical Guide.

🌀 Step 5: Refrigerant Line Set

Installed pre-insulated copper: ¾” suction, ⅜” liquid.
Routed through the attic with wide bends to avoid pressure drop.
Secured every 4 ft with hangers.

👉 Pro tip: Avoid touching copper directly with bare hands — oil contamination can cause leaks.

🧪 Step 6: Leak Test & Evacuation

Tech steps:

Pressurised with nitrogen to 300 psi for 30 minutes.
Evacuated with a vacuum pump to 500 microns.
Verified vacuum hold.

Resource: HVAC School – Proper Vacuum Technique.

🔓 Step 7: Charging R-32

Opened service valves to release factory charge.
Adjusted for line set length (longer runs = extra refrigerant needed).
Checked pressures vs Goodman’s charts.

👉 Only a licensed HVAC pro can legally handle refrigerant (EPA 608 certification).

📲 Step 8: Thermostat Setup

Installed a smart Wi-Fi thermostat.
Configured for 2-stage cooling.
Synced to my phone for remote monitoring.

🔊 Step 9: Startup & Commissioning

Checked airflow: ~1,200 CFM total (400 per ton).
Verified superheat & subcooling matched manufacturer spec.
Confirmed no abnormal vibrations or noise.

🔍 5. Mike’s Tool List

Here’s what I actually used:

Cordless drill + bits
Torpedo & 4-ft level
Sheet metal snips
Foil tape + mastic brush
PVC cutter (for drains)
Nitrogen regulator (loaned from tech)
Vacuum pump (tech supplied)
Multimeter (for verifying power off)
Torque wrench (for line set flares)

⏱️ 6. Timeline & Workflow

Day 1: Demo old unit, reinforce platform, prep ducts.
Day 2 morning: Install air handler + duct connections.
Day 2 afternoon: Electrical + drain setup.
Day 3: Tech arrives for line set, vacuum, charge, and commissioning.

👉 From tear-out to first cold air: ~3 days.

💰 7. Cost Breakdown

Item	Cost
Goodman GPCH33631	$2,750
Line set & misc.	$450
Electrical labor	$600
Refrigerant hookup & commissioning	$750
Permits & inspection	$120
Platform/duct supplies	$300
Total	≈ $4,970

✅ 8. Post-Install Checklist

Before calling it “done,” I checked:

🧹 9. Maintenance Routine

Keeping the system healthy:

Replace filters every 60–90 days.
Flush the condensate line with vinegar every spring.
Rinse outdoor condenser coils twice per year.
Annual pro inspection (check charge, coils, amps).

Resource: Energy Star – AC Maintenance Tips.

🧭 10. Lessons Learned

Permits add time — apply early.
Prep is 50% of the job — strong platform, sealed ducts make all the difference.
Don’t skimp on drain safety — my float switch already saved me once.
Respect R-32 — mildly flammable, requires certified handling.
Budget wiggle room — my total ran ~$300 higher than expected due to extra PVC and mastic.

🏁 Conclusion — Was It Worth It?

Absolutely. My Goodman R-32 horizontal AC has been running smoothly, efficiently, and quietly. The install wasn’t “easy,” but by tackling the prep and knowing when to call in pros, I:

Saved ~15% on labour
Gained confidence in the system’s quality
Future-proofed against the R-410A phase-out
Learned a ton I can apply to future projects

If you’re planning your own install, I hope my walkthrough helps you avoid pitfalls and set up a system you can rely on for decades.

In the next blog, we shall learn more about How Much Does a 3 Ton Goodman Horizontal AC Cost in 2025? Mike’s Budget Breakdown

Tags: Cooling it with mike

WRITTEN BY

Mike Sanders

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