0 comments

3.5 Ton vs. 5 Ton A-Coils — Why Bigger Is NOT Always Better

Tony explains why oversizing your coil destroys comfort, kills efficiency, floods drain pans, ruins compressors, and makes your system run like garbage.

Let me tell you one of the biggest HVAC myths homeowners believe:

“A bigger coil means better cooling.”

Wrong.
Dangerously wrong.
If bigger were better, every house would have a 10-ton system crammed into the attic and we’d all sit in meat-locker conditions.

Cooling doesn’t work that way.
HVAC sizing is not like picking a bigger engine for your truck.

The Goodman 3.5–5 ton cased A-coil (CAPFA6030C3) is engineered for specific airflow ranges, specific tonnage pairings, and specific refrigerant performance targets. If you choose the wrong size coil for your system, you will DESTROY comfort and efficiency — and sometimes equipment.

Today Tony’s breaking down:

the real difference between 3.5 and 5 ton coils
why oversizing is a homeowner’s biggest mistake
how coil tonnage affects humidity control
why your condenser MUST match your A-coil
what happens when airflow is wrong
the symptoms of an oversized or undersized coil
how to choose tonnage the right way

Let’s start ripping apart this “bigger is better” myth once and for all.

First: What Does “Ton” Even Mean in HVAC?

Tonnage in HVAC has NOTHING to do with weight.

1 ton of cooling = ability to remove 12,000 BTUs of heat per hour.

So:

3.5 ton coil = 42,000 BTU capacity
5 ton coil = 60,000 BTU capacity

That’s a HUGE jump.
People treat 3.5 vs. 5 ton like choosing between medium and large fries — but it’s more like choosing between a half-ton truck and a full-blown dually.

Your home’s ductwork, airflow, and condenser all have to match the tonnage.

Here’s the deeper foundation for tonnage measurement:
[Cooling Capacity and BTU Requirements for Evaporator Coils]

Why Bigger A-Coils Don’t Automatically Mean More Cooling

Manufacturers design coils around:

airflow rate (CFM)
refrigerant metering (TXV/piston)
outdoor condenser tonnage
SEER2 efficiency targets
ductwork pressure limits

If the coil is bigger than the system can handle, you get:

✔ reduced refrigerant evaporation
✔ poor humidity removal
✔ inconsistent supply temperatures
✔ potential flooding of the compressor
✔ blazing high energy bills
✔ short cycling

Oversizing destroys efficiency.
It doesn’t increase it.

Here’s the science behind this mismatch:
[Evaporator Coil Sizing Effects on Refrigerant Evaporation Dynamics]

Why Undersizing the Coil Is Just as Bad

Let’s say you have a 5-ton condenser but install a 3.5-ton coil.

Congratulations — you’ve created a refrigerant disaster.

Your condenser will try to pump more refrigerant than your coil can evaporate. That creates:

high suction pressure
high compressor load
lower efficiency
higher head pressure
coil flooding
warm indoor air
premature compressor failure

Manufacturers size components TOGETHER for a reason.

How Coil Tonnage Affects Humidity Control (The Part Homeowners Don’t Understand)

Cooling = heat removal + humidity removal.
A bigger coil removes heat faster…
…but removes LESS humidity.

Let Tony explain:

A 5-ton coil evaporates refrigerant too quickly if paired with a smaller condenser or weak airflow.

That means:

less coil surface stays cold long enough
moisture doesn’t condense properly
humidity stays high
air feels clammy instead of crisp

Oversizing is the #1 cause of:

cool but wet homes
moldy basements
sticky upstairs areas
longer overall run times

You think the AC is “working harder.”
It’s not — it’s working WRONG.

Here’s why humidity depends on coil balance:
[Relationship Between Evaporator Coil Size and Latent Heat Removal]

Why Your Condenser MUST Match Your A-Coil

Goodman — and every major HVAC manufacturer — designs their equipment to work as matched systems.

A 3.5–5 ton coil doesn’t mean you can just “pick whatever ton you want.”
It means the coil supports that range when installed properly.

If you pair:

a 3.5-ton condenser with a 5-ton coil
OR
a 5-ton condenser with a 3.5-ton coil

…you’re asking for disasters like:

✔ refrigerant floodback
✔ compressor slugging
✔ overheating
✔ mismatched metering device
✔ wrong subcooling targets
✔ failed SEER2 efficiency
✔ noisy operation
✔ poor coil boiling pattern

Matching matters.

Here’s why manufacturers insist on it:
[System Matching Requirements for Evaporator and Condenser Performance]

The Real Differences Between a 3.5 Ton and 5 Ton A-Coil

Let’s break this down simply.

1. Coil Surface Area

5-ton coils have more surface area.
This changes:

heat absorption
refrigerant boiling
air distribution
latent (humidity) performance

2. Refrigerant Flow

Bigger coils allow more refrigerant flow.
Smaller coils restrict flow.

This affects:

superheat
subcooling
compressor protection
efficiency

3. Airflow Requirements

3.5-ton coil → around 1,400 CFM
5-ton coil → around 2,000 CFM

If your blower cannot hit the right CFM?
Your coil WILL freeze or flood.

4. Condensate Production

5-ton systems pull more moisture.
But if the airflow doesn’t support it, drainage becomes a mess.

5. Cabinet Fit

The Goodman CAPFA6030C3 fits a 21-inch width.
If your furnace width is 17.5" or 24.5", you need the correct coil size.

Bigger coils don’t fit smaller furnaces without creating airflow choke points.

Why Oversizing Causes System Failure (Tony’s Field-Truth Examples)

I see these failures every summer.

Failure #1: Oversized Coil + Undersized Blower = Frozen Coil

Your coil turns into a block of ice because airflow can’t keep up.

Failure #2: Oversized Coil + Wrong TXV = Flooded Compressor

Too much refrigerant returns as liquid → compressor dies.

Failure #3: Oversized Coil + Oversized Condenser = Short Cycling

Your AC turns on and off constantly → huge energy bills.

Failure #4: Oversized Coil + Weak Ductwork = Hot and Cold Spots

Air never distributes evenly → comfort dies.

Failure #5: Oversized Coil + High Humidity = Mold Risk

Your AC cools too fast → humidity stays high.

You see the pattern?

Oversizing doesn’t help ANYTHING.

Why Undersizing Causes System Failure (Just as Common)

A coil that’s too small for the condenser:

✔ overheats the compressor
✔ raises suction pressure
✔ creates refrigerant starvation
✔ lowers coil surface cooling
✔ reduces humidity removal
✔ forces longer run times

Undersizing kills compressors slowly — but surely.

The Perfect Scenario: Matching Tonnage the Right Way

For the Goodman CAPFA6030C3, the sweet spot is matching the coil to these:

3.5-ton condenser
4-ton condenser
5-ton condenser

— but ONLY with the correct TXV/piston and correct CFM airflow.

When matched correctly:

✔ refrigerant boils perfectly
✔ humidity drops properly
✔ coil stays cold but doesn’t freeze
✔ compressor stays protected
✔ SEER2 performance is achieved
✔ energy bills stay low
✔ comfort stays consistent

This is why you don’t guess tonnage.

Signs Your A-Coil Is Oversized (Tony’s Red Flags)

If any of these sound familiar, your coil may be too big:

AC cools fast but humidity stays high
supply air feels “cold but wet”
coil sweats excessively
coil floods during cycles
compressor sounds harsh
air temperature swings
short cycling
large temperature drop at coil (10+ degrees)
rooms never feel truly comfortable

Oversizing is more common than you think — especially with DIY installations.

Signs Your A-Coil Is Undersized

Opposite symptoms:

AC runs constantly
warm supply air
weak cooling output
high energy bills
compressor overly hot
long runtimes without achieving temperature
coil barely sweats
poor humidity removal

This is a system begging for proper sizing.

How Tony Determines Coil Tonnage the Right Way

Here’s Tony’s in-field method — the REAL one, not the marketing version:

✔ Step 1: Identify condenser tonnage

✔ Step 2: Identify furnace blower CFM capability

✔ Step 3: Check duct static pressure

✔ Step 4: Confirm coil cabinet width fits furnace perfectly

✔ Step 5: Confirm correct TXV/piston for refrigerant used

✔ Step 6: Match coil to AHRI-rated system configuration

This ensures:

correct airflow
correct refrigerant flow
correct capacity
correct humidity performance

This is how pros do it.

Here’s the AHRI key point:
[AHRI Matching Standards for Evaporator and Condenser Compatibility]

Tony’s Final Verdict

If you’ve ever believed that a 5-ton coil cools better than a 3.5-ton coil “because it’s bigger,” throw that idea in the trash.

Cooling doesn’t work like that.

Here’s the truth:

✔ A bigger coil can DESTROY humidity control
✔ A bigger coil can cause freezing
✔ A bigger coil can overload ductwork
✔ A bigger coil can flood your compressor
✔ A bigger coil can short cycle
✔ A bigger coil can collapse SEER2 efficiency
✔ A bigger coil can make your home MORE uncomfortable

Matching coil size to your system is everything.

The Goodman CAPFA6030C3 is an incredible A-coil — but only if you choose the correct tonnage and match it with the correct condenser and airflow.

Do it right, and your system runs quietly, smoothly, efficiently, and comfortably for years.

Do it wrong, and Tony will see you every summer.

Let's discuss how to match this A coil with the right Goodman condenser in the next blog.

Tags: Tony’s toolbox talk