PTAC Sizing & Compatibility Guide

Buying the right PTAC comes down to four things: the right cooling capacity for the room, a unit that fits your existing wall sleeve, the correct voltage and amperage for your electrical, and the heat type that suits your climate. Here is how to get each one right, or call us and we will spec it for you.

1

Size the Unit to the Room (BTU)

BTU (British Thermal Units) measures cooling capacity. Too small and the room never quite cools; too large and the unit short-cycles, wastes energy, and leaves the air feeling clammy. Use this as a starting point:

Capacity Approx. room size Typical hotel use
7,000 BTU Up to ~300 sq ft Smaller / single guest rooms
9,000 BTU ~300–400 sq ft Standard guest rooms
12,000 BTU ~400–550 sq ft Larger rooms & junior suites
15,000 BTU ~550–700 sq ft Suites & small common areas

Size up if the room has large sun-facing windows, high ceilings, top-floor exposure, poor insulation, or sits in a hot climate.

2

Check Your Wall Sleeve

Most PTACs install into a standard 42-inch-wide wall sleeve. Before you order:

  • Measure the interior width and height of your existing sleeve.
  • Confirm it is the industry-standard 42" size; older or non-standard sleeves may need replacing.
  • A solid, rust-free sleeve can usually be reused, which saves installation time and cost.
Tip: If your sleeve is rusted, damaged, or a non-standard size, ask us about replacement sleeves and grilles before you buy the unit.
3

Match Voltage and Amperage

Every PTAC is wired for a specific voltage and circuit size. Getting this wrong can mean the unit will not run, or will not run safely.

  • 208/230VThe most common in hotels and motels.
  • 265/277VFound in some larger commercial buildings.
  • 15A / 20A / 30AAmperage must match the dedicated circuit serving the unit.
Match both the voltage and amperage to your existing electrical, and when in doubt, confirm with a licensed electrician.
4

Heat Pump or Electric Heat?

Heat Pump

Moves heat for lower operating costs. Best in mild-to-moderate climates, and includes electric backup for cold snaps.

Electric Heat

Resistance heat that warms reliably in any climate, including hard winters. Simpler, with a higher running cost.

Rule of thumb: a milder climate and energy savings point to a heat pump; a cold climate and simplicity point to electric heat.

Still Not Sure? We Will Spec It for You

Tell us your room size, wall-sleeve dimensions, and the voltage in your building, and we will recommend the exact unit.

Call 865-456-0146 Request a Quote