If you’re shopping for a PTAC like the Amana Distinctions 12,000 BTU PTAC with 3.5kW heat, you’ll probably see a model number like PTH123G35AXXX.
Those last letters? They tell you the voltage—and it’s a BIG deal.
Hi, I’m Tony the Trusted Tech. Over the years, I’ve seen too many property owners buy the wrong voltage PTAC for their building. And it doesn’t just mean your unit won’t run—it can lead to blown fuses, damaged boards, or even fire hazards.
Let’s get this sorted.
The Two Most Common PTAC Voltages
Almost every modern PTAC comes in one of these two voltages:
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208/230V (usually marked “230V”): This is standard residential and light commercial voltage in North America. It comes from split-phase power (two hot wires).
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265V: This is commercial-only voltage, found in buildings with 3-phase wye electrical service—usually high-rises, hotels, or older commercial properties.
✅ 208/230V units are most common in motels, apartments, and small offices.
✅ 265V units are found in large buildings with rooftop or central electrical distribution.
Important: These are not interchangeable. A 265V unit will not run on 208V power—and vice versa.
👉 For a deeper technical dive, check out this NEC electrical service overview from Electrical Construction & Maintenance magazine.
How to Know What Voltage You Need
Here’s how I check a building’s power supply on the job:
1. Look at the Breaker Panel or Disconnect Box
Find the circuit that powers the PTAC. If it’s marked “208V” or “230V,” you’re good with a 208/230V unit. If it says “277V” or “265V,” you need a 265V unit.
2. Measure With a Multimeter
Check the voltage at the outlet or wiring with a true RMS multimeter. Just make sure the power is on and you’re following safety precautions.
3. Ask Your Electrician or Maintenance Team
If you're not sure, a licensed electrician can confirm your building’s voltage supply. This is especially important if you're replacing old PTACs or mixing different brands.
👉 Fluke Instruments has a great article on why using a true RMS meter is critical for HVAC systems.
What Happens If You Use the Wrong Voltage?
Using the wrong voltage unit isn’t just a mismatch—it can lead to serious problems.
If you install a 265V PTAC on 208V power:
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It may turn on weakly or not at all.
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The compressor may never start.
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You risk overheating the circuit board or capacitor.
If you install a 208V PTAC on 265V power:
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It may instantly fry the electronics.
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The control board can melt.
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You void the warranty and risk a fire hazard.
This isn’t a “try and see” situation—it’s a hard rule.
👉 According to the Air Conditioning, Heating, and Refrigeration Institute (AHRI), voltage mismatches are one of the top causes of PTAC unit failure.
Decoding PTAC Model Numbers
PTAC model numbers almost always end in a code that includes the voltage. Here’s how to read it:
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208/230V with 20-amp cord = A
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208/230V with 30-amp cord = B
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265V with 15-amp cord = C
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265V with 20-amp cord = D
Example:
PTH123G35A = 208/230V
PTH123G35D = 265V
Always check the data tag and label on the unit. You’ll usually find it behind the front panel near the blower motor.
Can You Use a Voltage Adapter?
Nope. There are no adapters or converters that safely change a PTAC’s voltage. These aren’t small appliances—they’re 3–5 kW power hogs. The only solution is:
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Replace the PTAC with the correct voltage unit, or
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Have an electrician modify the circuit (which is often expensive and may not meet code)
If you’re managing a multi-room property, label each PTAC’s circuit to avoid costly mix-ups in the future.
👉 This guide from ASHRAE explains best practices for commercial HVAC electrical service planning.
Tony’s Advice: Check Twice, Buy Once
If there’s one thing I always double-check before installing a PTAC, it’s voltage. It’s an easy mistake to make—and a very expensive one to fix.
When in doubt:
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Look at the circuit breaker or outlet
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Read the PTAC model number
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Test the line voltage
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Confirm with an electrician
Don’t assume. Ask and verify.
Coming up next in the series: “PTAC Amperage: How Many Amps Does Your Unit Pull?”
