What Size AC and Furnace System Do I Need? Mike Breaks It Down
Hey folks—Mike here again.
Let’s talk about one of the biggest decisions you’ll make when buying an HVAC system: sizing.
And no, I’m not talking about whether it’ll fit next to your house. I’m talking about tonnage and BTUs—the numbers that determine whether your new system keeps you cool and cozy, or wastes energy and jacks up your bills.
If you’re checking out systems like this Goodman 3 Ton 15.2 SEER2 R-32 AC and Gas Furnace System and wondering, “Is this the right size for my home?” —you’re not alone. Here’s how to figure it out the right way.
Step 1: Understand the Terms (Without the HVAC Jargon)
Let’s break down a few terms you’re gonna see everywhere:
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Tons – This refers to your air conditioner’s cooling capacity. One ton = the ability to remove 12,000 BTUs of heat per hour. Most homes need between 1.5 and 5 tons.
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BTUs (British Thermal Units) – For furnaces, this is how much heat it can produce. Higher BTUs = more heating power.
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SEER2 – This is your air conditioner’s efficiency rating. The higher, the better your energy savings.
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AFUE – This is the furnace’s efficiency. A 96% AFUE furnace (like the GR9T961005CN in our featured system) converts 96% of fuel into usable heat.
Step 2: Use the Square Foot Rule of Thumb
You’ll hear different ranges, but here’s the quick-and-dirty guide:
| Home Size (sq. ft.) | AC Size (Tons) | Furnace Size (BTUs) |
|---|---|---|
| 1,200–1,500 | 2–2.5 Tons | 50,000–70,000 |
| 1,500–2,000 | 2.5–3 Tons | 70,000–90,000 |
| 2,000–2,500 | 3–4 Tons | 90,000–100,000+ |
If your house is around 2,000–2,200 sq. ft., this Goodman 3 Ton / 100,000 BTU combo is a solid match.
Of course, that’s a generalization. There’s more to the story.
Step 3: Factor in Location and Insulation
A house in Minnesota needs more heating BTUs than one in North Carolina. Same goes for cooling in Phoenix versus Seattle. Climate makes a difference.
Also consider:
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Ceiling height
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Window quality and size
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Insulation levels (attic and walls)
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Shade and sun exposure
Pro Tip: Use a Manual J Load Calculation (many HVAC companies offer this for free). Or check out this handy HVAC sizing calculator from HVACDirect to get a ballpark.
Step 4: Bigger Isn’t Always Better
Oversized systems short-cycle. That means they turn on and off too fast, never running long enough to dehumidify or evenly heat the house. That leads to:
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Uneven temps
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Higher energy bills
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More wear and tear
Undersized systems? You’ll be cold, sweaty, and annoyed—and your unit will be working overtime.
Bottom line: Right-sized = comfort + efficiency.
Step 5: Why R-32 Systems Like This Matter
This system uses R-32 refrigerant, a low-GWP A2L refrigerant that’s safer for the planet and easier on your energy bill. Compared to older R-410A systems, it cools more efficiently with a smaller charge size.
As the industry moves away from legacy refrigerants and faces R-454B supply challenges, systems like this Goodman combo become a smart long-term choice.
Learn more about why R-32 is becoming the industry go-to from leaders like:
Step 6: When in Doubt, Ask a Pro (or Mike)
If you’re on the fence about sizing, don’t guess. Ask your HVAC contractor or reach out to a specialist at The Furnace Outlet. They’ll help you match your home’s needs with the right system—and make sure you don’t overspend.
Final Thoughts from Mike
Sizing isn’t just numbers—it’s peace of mind. You want a system that keeps you comfortable year-round, runs efficiently, and doesn’t die before its time.
This Goodman 3 Ton, 15.2 SEER2 R-32 AC and 100,000 BTU furnace setup? That’s a workhorse. If your home’s in that sweet spot around 2,000 square feet, it might just be your perfect match.
My Next topic will be on: How to Know When It’s Time to Replace Your Furnace (Not Just Repair It)
Catch you next time—
Mike
