A PTAC is a self-contained heating and cooling unit installed through an exterior wall, most commonly found in hotel rooms, assisted living facilities, and apartment buildings. The entire system, compressor, coils, fan, and controls, sits inside a single chassis that slides into a standardized metal wall sleeve. No ductwork, no outdoor condenser unit, no refrigerant piping between components. Each room gets its own independent PTAC, so one guest can set 68°F while the room next door runs at 74°F.
How a PTAC Is Built
The unit splits into two sides within one enclosure. The indoor side faces the room and contains the evaporator coil, blower fan, air filter, and controls. The outdoor side vents through the wall and holds the condenser coil and compressor. A partition inside the chassis separates the two airstreams.
Most PTACs fit a standard 42-inch wide by 16-inch tall wall sleeve, which means replacement is a chassis swap rather than a construction project. A maintenance worker can pull the old unit, slide in the new one, and plug it in within an hour. That interchangeability is the main reason hotels adopted PTACs at scale: a failed unit in Room 312 does not affect Room 314, and the fix does not require an HVAC contractor.
Capacity and Heating Options
Capacity Range |
Heating Type |
Where It Fits |
7,000-9,000 BTU |
Electric heat strip |
Smaller hotel rooms, 200-300 sq ft |
9,000-12,000 BTU |
Heat pump with electric backup |
Standard hotel rooms, 300-450 sq ft |
12,000-15,000 BTU |
Heat pump or hydronic coil |
Larger suites, senior living units |
Heat pump models reverse the refrigerant cycle to provide heating, which uses less electricity than a resistive heat strip. In climates where outdoor temperatures regularly drop below 35°F, the heat pump loses efficiency and the electric backup strip takes over, so operating costs in cold regions run higher than in moderate ones.
PTAC Limitations
PTACs trade efficiency for simplicity. Their EER ratings typically fall below those of ductless mini-splits at comparable capacities, and the wall penetration creates a thermal bridge that allows some heat transfer regardless of insulation. Noise is another trade-off: the compressor sits inside the room, separated from the occupant by only the chassis housing. Newer inverter-driven PTAC models have closed some of this gap on both efficiency and noise, but the format's constraints remain compared to split systems where the compressor lives outdoors.