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Retrofitting Older Homes with a Goodman 2.5-Ton Package Unit: Challenges & Solutions

Introduction

Installing a brand-new HVAC system in a 20-year-old home? That’s not a project — that’s an adventure.
And when homeowners call me asking about upgrading to the Goodman 2.5-Ton 13.4 SEER2 Self-Contained Horizontal Package AC Unit, the first question I ask isn’t “what’s your budget?” — it’s “how old is the ductwork?”

Older homes can absolutely benefit from a modern package system, but it’s not as simple as swapping out boxes. Every retrofit has its surprises — hidden insulation gaps, outdated wiring, or duct sizes that make me wonder what decade they were designed for.

So in this post, I’ll walk you through:
✅ The biggest retrofit challenges I see when installing Goodman horizontal package systems
✅ Practical solutions that balance cost, efficiency, and code compliance
✅ Real-world field advice for getting it right the first time

If you’re upgrading an older home, this guide will help you avoid the most common pitfalls and make your investment feel like new-home comfort.

1. Why a Goodman Horizontal Package Is a Smart Choice for Retrofits

Before we talk about problems, let’s talk about why this system is perfect for older homes in the first place.

The Goodman 2.5-Ton Horizontal Package Unit combines the evaporator coil, compressor, and blower into a single cabinet. That means:

No indoor air handler to replace
Fewer refrigerant lines
Simplified electrical and drainage setup

For homes that weren’t designed for central AC, that’s a game-changer. You can mount the unit outside, connect ductwork directly, and free up indoor space.

In short, less mess, fewer parts to fail, and faster cooling.

(Energy.gov – Central Air Conditioning Overview )

2. Challenge #1 — Outdated Ductwork Design

Here’s where most retrofits start wrong. Older homes often have undersized, leaky, or poorly insulated ducts. Back in the day, we didn’t have SEER2-rated systems or static pressure standards — so duct design was more guesswork than science.

The Problem

Ducts too small for modern airflow requirements
Crushed or kinked flex ducts in attics
Leaky joints waste 20–30% of conditioned air

That means your shiny new Goodman will work twice as hard to push air through a system that can’t handle it.

Tony’s Fix

Calculate duct sizing for 400 CFM per ton (1,000 CFM total for 2.5 tons)
Upgrade main trunks to at least 16-inch diameter supply and 14-inch return.
Seal all joints with mastic, not duct tape.
Add insulation (R-6 minimum) to attic ducts.

“You can’t expect a race car to perform on flat tires — airflow is everything.”

(Energy Star – Duct Sealing Guide )

3. Challenge #2 — Electrical Limitations

Older homes often have 100-amp service panels, aluminum branch wiring, or outdated breakers.
The Goodman package needs a dedicated 240V line with 30–35 amps, plus a weatherproof disconnect within sight.

The Problem

Old panels can’t support the amperage safely.
Breakers trip during startup
Lack of grounding or GFCI protection

Tony’s Fix

Hire a licensed electrician to verify service load capacity.
Upgrade wiring to 10 AWG copper minimum.
Add a 60-amp fused disconnect near the unit.
Bond and ground per NEC 2023 standards

This isn’t optional — bad wiring doesn’t just cause performance drops; it’s a safety risk.

(NFPA 70 – National Electrical Code )

4. Challenge #3 — Tight or Inaccessible Installation Areas

Many older homes were never designed for modern mechanical equipment. I’ve had to shoehorn units into crawlspaces, narrow side yards, or under decks — none ideal for air circulation or maintenance.

The Problem

Poor airflow due to clearance
No space for service access
Noise reverberating off nearby walls.

Tony’s Fix

Goodman’s horizontal discharge design helps, but placement still matters:

Maintain 24 inches of clearance on all sides and 60 inches above
Avoid corners or alcoves where sound can bounce.
If space is tight, build a small concrete pad extension to the side

A little extra effort up front prevents years of noisy operation or heat buildup.

(Energy.gov – Outdoor Unit Clearance Guidelines )

5. Challenge #4 — Poor Insulation and Air Leaks

It doesn’t matter how efficient your AC is if your house leaks air like a screen door.
Older homes often lack attic insulation, have single-pane windows, or leaky doors that throw efficiency right out the window.

Tony’s Fix

Before or during your retrofit, invest in a home energy audit to identify leaks.
Simple upgrades like:

Sealing attic penetrations with spray foam
Adding R-38 insulation
Installing weather stripping on doors
Using low-e window films

can improve comfort more than upgrading SEER2 alone.

(Energy Star – Home Energy Audit Guide )

6. Challenge #5 — Legacy Thermostats or Controls

A surprising number of older homes still run mechanical or mercury thermostats. These don’t play nice with modern 24V digital controls or smart systems.

The Problem

Incorrect wiring can short the control board.
Old two-wire setups lack a common “C” wire.
No scheduling or smart control features

Tony’s Fix

Upgrade to a Wi-Fi programmable thermostat that supports single-stage cooling.
If your system lacks a C-wire, use a C-wire adapter kit or a power extender.
You’ll get better temperature accuracy and long-term energy savings.

(Energy Star – Smart Thermostat Compatibility Guide )

7. Challenge #6 — Condensate Management in Older Structures

Drainage is a big deal, especially for retrofits. Older homes weren’t built with AC condensate lines in mind, so you’ll often find creative (and messy) solutions — like draining onto the lawn or back into crawlspace gravel.

Tony’s Fix

Route condensate lines to a dedicated drain or exterior line
Maintain a ¼-inch slope per foot.
Add a condensate safety switch to shut off power if the line clogs.
In basements, use a small condensate pump to lift water to a drain

It’s a small addition that prevents big water damage headaches later.

(Energy.gov – Condensate Drainage Guide )

8. Challenge #7 — Old Duct Returns Near Combustion Appliances

Here’s one most homeowners never consider — older HVAC setups often had return ducts near gas appliances like furnaces or water heaters. That’s a big problem in modern retrofits.

The Risk

Return ducts can draw in combustion gases (carbon monoxide) if installed too close to open flames or draft hoods.

Tony’s Fix

Relocate returns at least 10 feet away from gas appliances.
Add sealed combustion flues where possible.
Install a carbon monoxide detector near all fuel-burning devices

Safety first — quiet comfort means nothing if air quality’s at risk.

9. Challenge #8 — Uneven Air Distribution in Two-Story Homes

Older two-story homes often have poor duct zoning — cool air dumps upstairs while downstairs stays muggy. The Goodman’s single-stage design cools evenly, but only if airflow is balanced.

Tony’s Fix

Add manual balancing dampers on branch ducts.
Use adjustable supply grilles to fine-tune rooms.
Consider smart thermostats with remote sensors for multi-floor comfort

It’s not about upgrading to zoning systems — just about giving the air somewhere balanced to go.

10. Challenge #9 — Roof or Ground Mounting Decisions

Older homes don’t always have space for ground-mounted systems, and rooftop installs come with their own rules.

Tony’s Take

Ground mount = easier service, quieter, less heat exposure
Roof mount = better drainage and airflow, but needs proper flashing

If you’re replacing an old roof unit, always inspect curb flashing for leaks and seal with a UV-rated roofing sealant.
And if moving the unit to ground level, make sure condensate lines and ducts are rerouted properly with insulation sleeves.

11. Challenge #10 — Matching SEER2 Efficiency to Older Homes

Homeowners sometimes expect instant 50% bill savings with a new AC, but older homes’ thermal envelopes limit what’s possible.
A 13.4 SEER2 system like Goodman’s is efficient, but if your attic leaks, your bills won’t show the full benefit.

Tony’s Advice

Combine the system upgrade with:

Attic sealing and insulation improvements
Smart thermostat scheduling
Regular filter changes
Annual coil cleaning

That’s how you unlock true SEER2 efficiency in older construction.

12. Challenge #11 — Noise and Vibration on Old Foundations

I’ve seen older concrete pads that look like they survived an earthquake. If your pad vibrates, your AC will too.

Tony’s Fix

Replace cracked pads with a new composite base.
Add rubber isolation feet under the unit.
Ensure all four corners are level within ¼ inch.

This one simple upgrade reduces vibration noise by 50% and keeps components from loosening over time.

13. The Retrofit Success Formula

After 200+ retrofits, I’ve boiled success down to three simple principles:

Start with airflow. Size and seal the ducts before even unboxing the unit.
Fix the envelope. Seal the house — don’t just upgrade equipment.
Plan for serviceability. Leave access room, add a drain cleanout, and label everything.

When you get those three right, a Goodman horizontal package runs like it’s tailor-made for your home.

14. Real-World Case Study — 1970s Ranch Retrofit

A client in Tennessee wanted to replace their 25-year-old split system. We installed a Goodman 2.5-ton horizontal package unit in the side yard.

The Challenges

6-inch undersized ducts
12-inch attic insulation (R-19)
Old 20-amp circuit feeding the previous system

The Fix

Upgraded ducts to 16-inch supply / 14-inch return
Blew in R-38 insulation
Added a 35-amp dedicated circuit and a new pad

Results

Indoor temperature dropped 4°F faster on startup.
Energy bills reduced by 22%
Noise cut by half
Return air humidity stabilized at 47%

That’s a retrofit win by any standard.

15. The Bottom Line — Bringing Old Homes Into the Modern Comfort Era

Retrofitting an older home isn’t just about replacing equipment — it’s about restoring balance.
When you combine modern Goodman engineering with a thoughtful installation plan, even a 1960s house can deliver 2025-level comfort.

✅ Quieter operation
✅ Lower bills
✅ Consistent airflow
✅ Simple maintenance
✅ 10-year reliability

That’s why I tell homeowners: “Don’t let your home’s age hold you back. With the right prep, it’ll cool better than it ever did new.”

Tony will help us in choosing the right dealer for your Goodman package AC in the next blog.

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