A PTAC is the self-contained unit you have seen under hotel windows. When it includes a heat pump it is called a PTHP, and it heats and cools a single room through one through-the-wall package. It fits rooms and buildings where a central system does not.
What a PTAC and PTHP are
A PTAC is a compact, all-in-one room unit. As defined in the reference literature, a PTAC is a self-contained heating and air conditioning system intended to be mounted through a wall, and those that include heat pumps are called PTHPs. Functionally, the unit pulls warm indoor air across internal cooling coils, filters it, and blows cooled air back into the room while venting heat outdoors. Because everything is in one package that pierces an exterior wall, a PTAC conditions its room without ducts or a separate outdoor condenser.
Where they are used and their capacity
PTACs dominate certain buildings. They are commonly found in commercial settings such as hotels, motels, and hospitals, and in multifamily facilities like senior housing, condominiums, and apartment buildings. On capacity, typical PTAC heating and cooling values range from 7,000 to 19,000 BTU per hour, or about 2 to 5.5 kilowatts nominal. That range makes a single PTAC well matched to one guest room, apartment, or addition, which is why they are specified room by room rather than as a whole-building system.
The wall sleeve and installation
Installation centers on the wall sleeve. PTACs are commonly installed in window walls and masonry walls, with standard sleeve dimensions including 42 by 16 inches, 36 by 15 inches, and 40 by 15 inches. Every new through-the-wall installation requires a metal wall sleeve to support the unit's weight and protect the surrounding wall, and it must be on an exterior wall. Matching the new unit to an existing sleeve size, or building the correct sleeve into an exterior wall, is the core of a PTAC install.
Cold-weather limits and an example spec
The heat pump in a PTHP saves energy, but it is not a deep-cold heater. The Furnace Outlet notes heat pumps use less electricity than electric resistance heaters, but performance can diminish in extremely low temperatures, often requiring auxiliary heat, which is why many PTHPs include an electric resistance backup. As a concrete example, the Amana PTH074G25AXXX provides 7,700 BTU cooling and 6,800 BTU of heat pump capacity, with a 2.5 kW electric heater, an EER of 11.7, R410a refrigerant, and 265V operation. That built-in electric heater is the backup that covers the coldest days the heat pump cannot.
Frequently asked questions
What is a PTAC or PTHP?
A PTAC is a self-contained heating and cooling unit mounted through a wall. When it includes a heat pump it is called a PTHP, conditioning one room from a single through-the-wall package.
Where are they typically used?
They are common in hotels, motels, hospitals, and multifamily buildings such as senior housing, condominiums, and apartments, specified room by room.
What capacity do they come in?
Typical PTAC heating and cooling capacity ranges from 7,000 to 19,000 BTU per hour, about 2 to 5.5 kilowatts nominal.
Do they need a wall sleeve?
Yes. Every new through-the-wall installation requires a metal wall sleeve on an exterior wall to support the unit and protect the wall. Standard sleeve sizes include 42x16, 36x15, and 40x15 inches.
Do PTHPs work in very cold weather?
With limits. The Furnace Outlet notes heat pump performance diminishes in extreme cold, often requiring auxiliary heat. Many units, like the Amana example, include a 2.5 kW electric backup heater.