Intro: Bigger Isn’t Always Better in HVAC – But It Might Be Necessary
Every time I walk onto a job site, someone asks me the same thing:
“Do I need a 5 ton commercial AC unit, or will a 3-ton get the job done?”
It’s a fair question. In the commercial HVAC world, it’s easy to overpay for the wrong size system—or undersize and suffer from hot spots, high humidity, and miserable employees or customers.
I’ve been doing this for more than 30 years, and here’s what I’ll tell you straight: size absolutely matters, but not the way you think. Let’s break down the difference between 3 ton commercial AC units and 5 ton commercial AC systems, when to use each, what’s changing with refrigerants, and why the right choice will save you thousands down the line.
What Does 3 Ton or 5 Ton Really Mean?
Let’s get this out of the way:
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1 “ton” of cooling = 12,000 BTUs/hr
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A 3-ton commercial AC unit = 36,000 BTU/hr
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A 5-ton commercial AC = 60,000 BTU/hr
Simple enough—but that doesn’t mean you can just multiply your square footage and slap a unit on the roof. Commercial HVAC sizing depends on heat load calculations, insulation, ductwork design, sun exposure, and internal heat from equipment and people.
According to HVAC.com’s guide to AC tonnage, a 5-ton unit typically covers 2,500–3,000 square feet of commercial space under average conditions. But in reality, I’ve seen 5-ton units in 2,000-square-foot server rooms and 3-ton systems fail to cool open floor plan offices with floor-to-ceiling windows.
3-Ton Commercial AC Units: Small Space, Big Value
3-ton commercial systems are popular for good reason—they’re budget-friendly, easy to install, and ideal for:
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Small retail shops or boutiques
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Office suites under 2,000 sq ft
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Conference rooms or training centers
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Kitchens or break rooms with limited duct space
Most are single-phase, come with pre-charged R-410A, and can run on existing ductwork if properly sized. I often pair them with programmable thermostats to maximize comfort and efficiency.
However, you’ll want to avoid pushing them past their limit. Short-cycling, humidity imbalance, and premature wear happen when you ask a 3-ton unit to cool a 2,500 sq ft restaurant with a flat black roof.
Want an expert take on commercial load sizing? Check out this explainer from the Department of Energy. It shows why proper sizing is more important than just the tonnage label.
When to Step Up to a 5-Ton Commercial AC Unit
If your cooling load is significant—whether from square footage, poor insulation, or high occupancy—a 5 ton commercial AC unit is usually the right call. I typically recommend 5-ton models for:
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Restaurants and cafes with large kitchen areas
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Medical clinics or vet offices
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Medium-sized retail stores
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Server rooms or IT centers
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Fitness studios or gyms
Most commercial 5-ton units are available in three-phase for smoother operation and energy efficiency, though you can find single-phase options for light commercial installs.
You’ll also want to think long-term. 5-ton systems usually have sturdier cabinets, higher efficiency options (14–16 SEER2), and better compatibility with zoning controls or energy management systems.
For more on when a 5-ton system makes sense, NinjaHVAC has a helpful guide for business owners.
R-32, SEER2, and Why Efficiency Should Guide Your Decision
Let’s talk about refrigerants. Older 3 ton and 5 ton commercial AC units mostly use R-410A, which is being phased out. The EPA is pushing for low-GWP refrigerants like R-32 and R-454B, which are more efficient and environmentally responsible.
R-32 systems, like the one I’ll mention shortly, offer:
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~10% better heat exchange efficiency
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Lower refrigerant charge
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1/3 the global warming potential (GWP) of R-410A
What’s more, newer SEER2 standards mean manufacturers are engineering better systems from the ground up. Higher SEER2 (14.5 or more) can translate to hundreds in annual energy savings—especially for 5-ton systems running 10+ hours a day.
Need help understanding SEER2 ratings? This Trane article breaks down what changed in 2023.
Real Talk: Budget, Maintenance, and Parts Availability
Now let’s talk brass tacks.
| System | Average Equipment Cost | Installed Price Range |
|---|---|---|
| 3-Ton | $2,500–$4,500 | $4,500–$7,500 |
| 5-Ton | $3,800–$7,000+ | $6,500–$12,000 |
A properly installed 3-ton system can be a good entry point, but if your demand creeps up, you’ll pay more over time for poor performance or early replacements.
With 5-ton commercial systems, expect more robust components and longer service life—if you keep them maintained. My advice? Always go with brands that have strong parts availability in your area. There’s nothing worse than needing a contactor or control board and waiting three weeks for a special order.
Why I Like This R-32 Goodman 3-Ton System for Light Commercial
For smaller spaces or auxiliary zones, one of my favorite systems is the Goodman 3 Ton 14.5 SEER2 R-32 Bundle. It’s ideal for business owners who want:
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High efficiency with R-32 refrigerant
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Trusted Goodman reliability (backed by Daikin)
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Quiet operation, even under heavy use
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Easy installation and service access
No, it’s not a 5-ton system—but if your space falls within 1,200–1,800 sq ft with good airflow, this setup delivers like a champ. You also future-proof yourself against refrigerant regulations and can still qualify for many local utility rebates.
5 Key Tips Before You Buy Any Commercial AC Unit
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Size the system based on real load calculations. Don’t guess. Use Manual N (commercial equivalent of Manual J) for accurate numbers.
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Think about future-proofing. R-32 or R-454B refrigerants will be standard by 2025. Avoid systems stuck with outdated tech.
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Check your electrical phase. A 5-ton unit might need three-phase power. Know what you’re working with before you buy.
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Look at SEER2 ratings. Anything under 14 SEER2 is going to cost you on utility bills.
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Talk to a real tech. A local installer can help identify ducting or zoning issues that affect performance more than tonnage ever will.
Final Word from the Field
Here’s what I tell every commercial client:
You’re not just buying an AC unit. You’re buying performance, reliability, and operating costs for the next 10–15 years.
A 3 ton commercial AC unit might be the perfect fit for your dental office, while your gym absolutely needs a 5 ton commercial AC to handle the sweat and traffic. Match the system to your needs, don’t over- or under-spend, and be smart about refrigerants and efficiency.
And if you’re stuck between a few models, get a second opinion from an installer who’s actually worked with those systems in the field—not someone reading specs off a brochure.
I’ve put in my time under ceilings, on rooftops, and in attics across the country. If you need advice, I’m always glad to give it to you straight.
—Mark Callahan
