Rooftop AC Unit for Sale: Shop Commercial Units by Size

Buying a rooftop ac unit for a commercial building usually comes down to one number first: tonnage. If the size is right, your tenants, staff and customers stay comfortable all summer. If it's wrong, you get either a unit that runs nonstop on hot afternoons or one that cools too fast and leaves the air damp and clammy.

At ACUnitsForLess, commercial rooftop units run from 3 ton up to 25 ton, from Daikin and Trane, in cooling-only, heat pump and gas/electric versions. You can see the straight-cool options in the light commercial packaged air conditioner collection. This guide shows you how to match the size and type to your building, which specs to check, and the mistakes buyers make most often.

What Is a Rooftop AC Unit?

A rooftop package unit puts everything in one cabinet: compressor, condenser coil, evaporator coil, blower and (on some models) a heat section. It sits on a roof curb, and the supply and return air travel straight down into the ductwork below.

That's why most strip malls, restaurants, clinics and small office buildings use them. You keep the equipment off the floor, the noise stays outside, and there's no separate indoor air handler taking up a closet.

The tradeoff is roof access. Every filter change and seasonal check happens up top, so make sure the building has a safe hatch or ladder before you commit to a rooftop setup.

How to Shop Rooftop AC Units by Size

Quick answer: Most small and mid-size commercial spaces use 3 to 10 ton units. A rough starting point is 1 ton for every 300 to 400 square feet of office or retail space. Restaurants, gyms and spaces with lots of glass or people usually need more, so always confirm with a commercial load calculation.

Here's a quick reference based on that rule of thumb:

Treat these numbers as a starting range, not a final answer. A 2,000 sq ft pizza place with two ovens running all day is a very different load than a 2,000 sq ft insurance office.

3 to 6 Ton: Small Offices, Shops and Clinics

This is the most common range for single-tenant spaces. Daikin's DHC packaged air conditioners come in 3, 4 and 5 ton sizes, and the DHH packaged heat pumps cover 3 through 6 ton. You can compare every size in the light commercial packaged heat pump range.

One detail people miss: not every small building has three-phase power. If yours is single-phase, look at models like the Daikin DHC0481 (4 ton) or DHC0601 (5 ton), both built for 208-230V single-phase. A three-phase unit won't run on single-phase power, so check this before you order.

7.5 to 12.5 Ton: Retail Stores, Restaurants and Larger Offices

Say you're outfitting a 4,000 sq ft retail store. At about 350 sq ft per ton, you land near 11 ton, so you'd likely compare a 10 ton and a 12.5 ton unit and let the load calculation decide.

In this range, you'll find the Daikin DHC series in 7.5, 8.5, 10 and 12.5 ton (the 7.5 ton models are rated at 17.5 IEER), Daikin DBH packaged heat pumps in 10 and 12.5 ton, and Trane THK packaged cooling units in 7.5, 8.5 and 10 ton.

15 to 25 Ton: Large Floor Plans

Bigger spaces open up a real choice: one large unit or two smaller ones. We usually lean toward two units for spaces above 15 ton. If one goes down on a July afternoon, the other keeps the building partly cool instead of leaving it with nothing.

Options here include Trane EDK Symbio units in 15 and 25 ton, Trane THK in 20 and 25 ton, and Daikin DSG gas/electric units in 25 ton.

Pick the Right Type of Rooftop HVAC Unit

Size tells you how much cooling you need. Type tells you how the building gets its heat. Every rooftop hvac unit on the site falls into one of three groups.

Cooling-Only Packaged AC

These are the straight-cool models, best for buildings in hot climates where heating is minor or handled another way. If you mainly need reliable cooling at a lower upfront cost, this is usually the simplest choice.

Packaged Heat Pump

A heat pump cools in summer and reverses to heat in winter, all on electricity. It works well in mild-winter regions like the Southeast and much of Texas, and for buildings without a gas line.

Gas/Electric Package Unit

This rooftop package unit pairs electric cooling with a gas furnace section, so it's the usual pick for colder climates where gas is available. Pay attention to heating input, because it varies within the same tonnage. For example, the Daikin DSG 25 ton comes in 260K, 360K and 400K BTU heat versions. See the full lineup in the light commercial packaged gas electric collection.

Specs to Check Before You Buy a Rooftop Air Conditioner Unit

Two units with the same tonnage can be very different machines. Before you add a rooftop air conditioner unit to your cart, check these details:

• Voltage and phase: Commercial units come in 208-230V single-phase, 208-230V three-phase, 460V and 575V. The unit has to match the power already at the building.

• Efficiency rating: Units of 65,000 BTU/h and up (about 6 tons and larger) are rated by IEER (Integrated Energy Efficiency Ratio), which measures part-load performance. Smaller 3 to 5 ton units are rated by SEER2. In both cases, a higher number usually means lower operating costs.

• Refrigerant: Daikin's DHC, DHH and DSG models use R-32, and Trane Foundation series units use R-454B. Both are lower-GWP refrigerants that follow the newer EPA rules.

• Footprint and curb fit: If an old unit is coming off the roof, measure the existing curb. A unit that matches the curb saves time, money and roof work.

• Airflow direction: Downflow units send air straight into the curb below. Horizontal units connect from the side, which fits some building layouts better.

• Heating input (gas units): Match the BTU heat output to your winter needs, not just the cooling tonnage.

• Add-ons: Economizers and fresh air dampers help with ventilation code and free cooling on mild days.

A practical tip: photograph the nameplate on your current rooftop ac unit before you start shopping. Model number, voltage, phase and tonnage are all on that label, and it answers half the questions above in about ten seconds.

Common Mistakes When Buying a Rooftop AC Unit

Ordering the wrong voltage. This happens more than you'd think. A building has 208V power and someone orders a 460V unit because the model number looked right. Confirm the voltage on site, not from an old invoice.

Going bigger "just to be safe." An oversized rooftop ac unit cools the space fast, shuts off, and never runs long enough to pull moisture out of the air. Restaurants and gyms feel this most. The room hits the thermostat setting but still feels sticky. This guide on Rooftop HVAC Systems explains how the right setup affects comfort across a commercial building.

Comparing the wrong ratings. Smaller rooftop units under 65,000 BTU/h (roughly 5 ton and below) carry SEER2 ratings, while 6 ton and larger units list EER and IEER. Compare SEER2 to SEER2 and IEER to IEER, never one against the other.

Forgetting about delivery. Commercial units ship palletized by freight and can weigh well over a thousand pounds at the larger sizes. Plan roof access, a crane or lift, and someone on site to receive the shipment before the delivery date.

Why Buy Rooftop Air Conditioning Units From ACUnitsForLess

ACUnitsForLess is an authorized dealer for the brands it carries, including Daikin and Trane. That means you're buying factory-new equipment from the actual manufacturer lineups, not mystery stock.

A few things make buying commercial rooftop air conditioning units here easier:

The range is wide. You can compare cooling-only, heat pump and gas/electric units side by side, from 3 ton up to 25 ton, and in every common commercial voltage.

The site also runs a B2B program for contractors, property managers and businesses that buy in volume, and financing is available at checkout for qualified buyers. If you already lean toward one brand, the Daikin HVAC collection brings its lineup together in one place, so you can compare tonnage, voltage and efficiency side by side without jumping between pages.

Final Thoughts

Start with your square footage and the rough tonnage range, then narrow it down by heating type, voltage and curb size. Get those four right and the rest of the decision gets simple.

Have your nameplate photo and building details ready, and shopping for a new rooftop ac unit by size gets much faster. If you're stuck between two tonnages, the ACUnitsForLess team can help you compare models before you place your order.

FAQs

Q1. What size rooftop HVAC unit do I need for my building?

A rough guide is 1 ton per 300 to 400 sq ft of office or retail space. Restaurants, gyms and spaces with heavy sun exposure need more. A commercial load calculation gives the exact size.

Q2. What is the difference between a rooftop package unit and a split system?

A package unit holds every component in one outdoor cabinet. A split system divides them between an outdoor condenser and an indoor air handler or furnace.

Q3. Can I get a commercial rooftop unit in single-phase power?

Yes. Some models, like the Daikin DHC0481 (4 ton) and DHC0601 (5 ton), run on 208-230V single-phase power.

Q4. What is IEER on a rooftop air conditioner unit?

IEER stands for Integrated Energy Efficiency Ratio. It measures how efficiently a unit runs at part load, which is how it operates most of the time. It's used for units of 65,000 BTU/h (about 6 tons) and larger; smaller units use SEER2.

Q5. Should I choose a heat pump or gas/electric rooftop unit?

Pick a heat pump if your winters are mild or the building has no gas line. Pick gas/electric if your winters are cold and natural gas is available.