Before You Order a System Online Samantha’s 7-Point Checklist to Verify Your Home’s True Tonnage

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Online HVAC shopping is one of the smartest ways to save money today. But unlike hiring a contractor who sizes the system for you, buying online means you’re responsible for choosing the correct tonnage.

And sizing is NOT something to guess on.

Choose too small → your AC runs nonstop, can’t keep up, and humidity climbs.
Choose too big → you get short cycling, uneven cooling, coil freeze, and real comfort issues.

That’s why I created Samantha’s 7-Point Tonnage Verification Checklist, built from years of real homeowners, real homes, and real HVAC diagnostic data.

This is the exact system-sizing method I use before I recommend ANY 2-ton, 3-ton, 3.5-ton, or 4-ton system — especially when someone is about to order a Goodman, MRCOOL, Amana, or R-32 condenser online.

Goodman 3.5 Ton 15.2 SEER2 System

Let’s walk through my complete, homeowner-safe, data-backed method.

**🏠 1. Confirm Your Real Square Footage (Not the Number on Zillow)**

Square footage is the starting point for tonnage — but many homeowners look at the wrong number.

Online listings show:

Total building square footage
Garage square footage
Basement square footage
Unfinished areas

That’s not what your AC is cooling.

✔ Use ONLY conditioned, finished square footage

Included:

Bedrooms
Living room
Kitchen
Finished basements (if vented)
Bonus rooms
Hallways

NOT included:

Garage
Attic
Crawlspace
Unfinished basement
Sunrooms without ducts

✔ Samantha’s Square Footage → Tonnage Baseline

Assuming average insulation & a mixed climate:

1,000–1,300 sq ft → 1.5–2 tons
1,300–1,700 sq ft → 2–2.5 tons
1,700–2,200 sq ft → 2.5–3 tons
2,200–2,600 sq ft → 3–3.5 tons
2,600–3,000 sq ft → 3.5–4 tons

This ONLY sets your starting range.
Your real tonnage depends on the next 6 factors.

External Verified Source:

DOE guidance on home energy sizing and square footage considerations

🌡 2. Identify Your Climate Zone — Your Zip Code Changes Your Ton Needs

Your cooling load depends heavily on outdoor temperature, humidity, and seasonal variation.

Two identical homes — one in Michigan and one in Florida — need entirely different AC sizes.

✔ Hot + Humid (FL, LA, SC, TX Gulf Coast)

Add 0.5 ton for humidity removal.

✔ Hot + Dry (AZ, NV)

Same tonnage as baseline, but airflow must be stronger.

✔ Mixed Climate (NC, TN, VA, MD, MO)

Square footage and insulation are the primary sizing factors.

✔ Cooler Northern States (MN, MI, WI, MA)

You often subtract 0.5 ton, because cooling demand is lower.

External Verified Source:

ASHRAE Climate Zone Map

🧱 3. Evaluate Insulation & Home Tightness — Oversized Systems Hide Here

Square footage doesn’t tell the whole story. Modern homes leak FAR less air.

✔ Insulation That Makes You Need Less Tonnage

R-38 to R-49 attic insulation
Spray foam attic or roof deck
Air-sealed can lights
Double- or triple-pane windows
Weatherstripped doors
R-8 duct insulation
ZIP System sheathing or housewrap
Tight envelope construction

These factors can reduce your cooling load by 10–25%.

✔ Insulation Problems That Increase Tonnage

R-19 or lower in attic
Uninsulated garage walls touching living space
Old metal-frame or single-pane windows
Leaky returns
Whole-house infiltration
Crawlspace air leaks
Attic knee walls

These issues can add 0.25–0.5 tons.

External Verified Source:

DOE attic insulation and air sealing standards:
https://www.energy.gov/energysaver/weatherize/insulation

☀️ 4. Check Solar Gain & Heat-Load Rooms — Your Biggest Hidden Tonnage Trap

A handful of rooms can dramatically skew your tonnage — even if the rest of the house is perfectly sized.

These are what I call Hot-Spot Load Adders.

✔ Rooms That Add 2,000–6,000 BTUs (Up to ½ Ton)

West-facing bedrooms
Rooms with large windows
Bonus rooms above garages
Finished attics
Sunrooms
Media rooms with multiple monitors
Home offices with PCs
Nursery with blackout drapes pulled open mid-day

✔ Samantha’s Solar Load Adjustments

Significant west-facing glass → Add 0.5 ton
Second floor always 3–5°F hotter → Add 0.5 ton
Bonus room above garage → Add 0.25–0.5 ton
Finished attic → Add 0.5 ton

External Verified Source:

ENERGY STAR on heat gain through windows

💨 5. Verify Your Duct System Can Support the Tonnage You Want

This is the #1 overlooked factor when homeowners buy online.

✔ You MUST have the airflow

Air conditioners require:

➡ 400 CFM (cubic feet per minute) per ton

Meaning:

2 tons = 800 CFM
3 tons = 1,200 CFM
3.5 tons = 1,400 CFM
4 tons = 1,600 CFM

If your ducts cannot move this much air, the tonnage you buy will not be the tonnage you feel.

✔ Signs Your Ductwork Is Undersized

Loud vents
Rooms with weak airflow
Dust streaks around registers
Very hot upstairs bedrooms
Return grille sounds like a “wind tunnel”
Short cycling
Coil freeze

✔ Samantha’s Duct Pass/Fail Criteria

Your ducts fail if:

Your supply trunk < 14”
Your return trunk < 16”
You have fewer than 3 return grilles
Flex duct is kinked
Your system is loud at startup
Your home uses only a single hallway return
Ductwork predates 1990 and hasn’t been upgraded

If your ducts fail → You may need to DOWNsize tonnage, not upsize.

External Verified Source: ACCA Manual D duct sizing reference

📱 6. Use a Smart Sensor to Confirm Real Runtime, Delta-T & Cycle Behavior

This is where you eliminate all guesswork.

Using a smart temp/humidity sensor (like the Amazon-linked temp/RH sensor you use in your content), you can measure the exact load your current system is handling.

Here’s what to check: