The Truth About 5-Ton Airflow:
Why Most Homes Can’t Handle It (And How to Fix That)**
Mike’s CFM, Static & Duct Reality Check for the Goodman 5-Ton R-32 System
Let me give it to you straight:
Most homes that “need” a 5-ton AC absolutely cannot handle a 5-ton AC.
**Not because of the condenser. Not because of the coil.
Because of the ductwork.**
The Goodman GLXS3B6010 5-Ton R-32 condenser is a monster in the best way.
Strong. Efficient. Reliable.
But it will only deliver its full power if the duct system feeding it is big enough, smooth enough, sealed enough, and balanced enough.
And here’s the uncomfortable truth:
80% of duct systems in American homes are undersized for 3 tons… let alone 5 tons.
Ready to see if your home can actually run a 5-ton system without choking it to death?
Let’s go.
1. A 5-Ton System Needs 2,000+ CFM — Period. Non-Negotiable.
A 5-ton AC isn’t a suggestion.
It’s a physical system with real airflow requirements.
5 tons = 2,000 CFM minimum
(That’s 400 CFM per ton.)
But here’s what most homes actually have:
-
1,200–1,400 CFM total duct capacity
-
One return grille the size of a cereal box
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Undersized flex runs
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6" supplies everywhere
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Choked transitions
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Leaky plenums
-
High static pressure
-
Old R-410A coil still being reused (don’t even get me started)
No duct system can magically produce airflow it’s not sized to carry.
The [High-Volume Residential CFM Requirement Matrix] shows that any system above 4 tons requires significantly larger duct trunks, more returns, and wider coil plenums.
Without 2,000+ CFM, your 5-ton system becomes a 3.5-ton system instantly.
2. Static Pressure Is the Silent Killer of 5-Ton Performance
Static pressure is airflow resistance.
Your blower is designed to move air, not fight air.
The Goodman 5-ton system needs:
0.50" WC (or less) total external static.
But most homes I test show:
0.75" – 1.20" WC.
That’s catastrophic.
High static causes:
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Loud returns
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Weak supply airflow
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Uneven room temperatures
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Coil freeze-ups
-
High energy usage
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Blower overheating
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Shortened compressor life
The [Static Pressure Loss & Duct Restriction Field Audit] shows that every 0.10" WC above the target range can reduce system capacity by 8–12%.
At 1.0 static?
Your 5-ton is delivering maybe 2.5–3 tons.
3. Your Return is Probably WAY Too Small for a 5-Ton System
Returns are the number one airflow bottleneck in homes.
Especially for big 5-ton setups.
A proper 5-ton return system requires:
At least 24–30 square inches of free area
AND
14–20" main return trunking
AND
multiple return grilles across the home
But most homes have:
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One hallway return
-
A 12" return duct
-
A noisy grille
-
A 1" filter rack from 1992
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A filter that’s already clogged
-
Terrible placement
The [Large-System Return Airflow Velocity Chart] warns that anything over 400 FPM (feet per minute) creates:
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noise
-
turbulence
-
high static
-
dust pull-in
-
coil imbalance
Your return should be QUIET.
If it sounds like a vacuum cleaner, you need more return area.
4. 6-Inch Flex Runs Cannot Feed a 5-Ton System — Stop Believing They Can
This one makes my blood pressure jump.
6-inch flex at best delivers:
60–90 CFM
A 5-ton system needs:
2,000 CFM.
That means:
-
Not 5 runs
-
Not 8 runs
-
Not 10 runs
You need:
12–16 supply runs built correctly
with 7–8" flex or, preferably, rigid.
The [Branch Duct Capacity & Flex Sagging Penalty Report] shows that 6" flex with even minor sag can lose 40–70% of its intended airflow.
Sag = drag.
Flex duct hates gravity.
Your AC hates sagging ducts.
5. The Evaporator Coil Must Be Oversized or Airflow Collapses
A 5-ton condenser NEEDS a big evaporator coil — bigger than 5 tons in many cases.
Why?
-
Larger coil = lower resistance
-
Lower resistance = lower static
-
Lower static = better airflow
-
Better airflow = better performance
This is why the High-Capacity Coil Pressure Drop Comparison Sheet recommends oversized coils on systems 4 tons and up.
If your coil is restrictive?
The blower will fight it.
The system will roar.
Your bills will climb.
And you’ll think the AC “isn’t strong enough.”
It’s not the condenser.
It’s your airflow.
6. If You Have Attic Ductwork, Your System Needs Even MORE Airflow
Attic ductwork heats up like crazy.
135°F attic = 20–40% airflow loss.
PLUS static increases by 0.05–0.20" WC just from duct heat expansion.
The [Thermal Load Impact on Attic Duct Performance Summary] shows that 5-ton systems experience disproportionate performance loss because:
-
higher airflow volumes accumulate more friction
-
heat infiltration increases linearly with duct length
-
flex ducts weaken under thermal load
-
insulation often degrades inside attics
If your ducts run through an attic, you need:
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more returns
-
larger supply trunks
-
shorter flex runs
-
rigid trunks
-
sealed plenums
-
insulated ducts
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attic ventilation
Otherwise your 5-ton AC is fighting a losing battle.
7. Signs Your Home Cannot Handle a 5-Ton System (Yet)
You probably need duct upgrades if:
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The return is loud
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Some rooms get no airflow
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The system “breathes” or pulses
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The AC runs but rooms stay warm
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Supply vents feel weak
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The coil freezes
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You hear hissing or whistling noises
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Ducts pop when the system starts
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Airflow drops when doors are closed
These symptoms are CLASSIC high-static, low-CFM red flags.
A Goodman 5-ton R-32 system is powerful — but if the ductwork is starving it, all that power becomes wasted energy.
8. How to Upgrade Your Home to Handle 5 Tons Like a Boss
Here’s Mike’s real-world duct upgrade plan:
✔ Add at least one NEW return (two if the home is large)
✔ Upgrade existing return to 16–20"
✔ Replace restrictive 1" filter rack with a 4–5" media cabinet
✔ Replace long flex runs with rigid duct
✔ Upgrade supply trunk to 14–18"
✔ Add more supply runs (7–8")
✔ Reduce flex sag
✔ Seal all duct connections
✔ Widen plenum transitions
✔ Improve attic ventilation/insulation
Do this, and your 5-ton will cool like a freight train on rails.
Skip any of this, and your 5-ton will cool like a Prius towing a boat.
9. Mike’s Final Verdict — Most Homes Aren’t Ready for 5 Tons… But They CAN Be
Here’s the blunt truth:
✔ A 5-ton system needs REAL airflow
✔ Most duct systems were NEVER built for 5 tons
✔ High static kills performance
✔ Undersized returns kill comfort
✔ Flex duct abuse kills CFM
✔ Attic ducts kill efficiency
✔ Oversized coils SAVE big-ton systems
Your Goodman 5-Ton R-32 condenser is NOT the problem.
Your ductwork is — until you fix it.
But once your ducts are sized and sealed correctly?
A 5-ton system becomes the most powerful cooling tool you’ll ever own.
That’s the Mike way.
Let's know about the installation costs in the next blog.
