Packaged terminal air conditioner is a self-contained air conditioner system that is commonly used in motels, apartments and smaller buildings in North America. It is mounted on the wall or window with ventilation option that brings fresh air from outside of the building and is individually controlled.

In other parts of the world, its similar counterpart is often known as window air conditioner. The standard size of 42″ Wide X 16″ High X 13 3/4″ deep is the common dimension that manufacturers have designed their units to fit the many replacement market in the United States. The common cooling capacity that you can choose from usually range from 7,000 to 15,000 BTUH.

It has an evaporator coil that faces the space to be cooled and a condensing coil that is mounted facing the outside of the building. A two speed or three speed fan is used to discharge the cool air to the room.

Packaged thermal air conditioner, seen close up, installed on a ceiling

The internal view of the components that made up the self-contained packaged terminal air conditioner unit.

Notice the compressor and the condensing coil at one side and the control at the other side.

Some units come with the heat pump version which is usually known as PTHP or Packaged Terminal Heat Pump. In this case, the same unit that is being used for cooling during warm weather is now being used for heating during cool weather. The heating cycle is known as reverse cycle where a 4 Way Valve is used to reverse the flow of the refrigerant. Other units come with an auxiliary heater as a supplement to the heating process in the event that the heating capacity is not enough during winter.

There are also options for heating units using hydronic or electric heater.

Packaged Terminal Air Conditioner Controller

The older units usually use mechanical control with mechanical push buttons to select the mode of operation and fan speed control. Another rotary knob is used to set the desired temperature of the unit. This was the most cost effective and simplest method of control in the past.

The development and the reduction in cost of electronic controls have enabled manufacturers to implement electronic control touch pad that comes with remote control. Some of the electronic controls that have been built into the system include:

  • Timer Control where you will be able to set when to ON or OFF the unit.
  • Mode control is operated by pushing the same button to select the mode of operation.
  • Temperature setting is displayed by the use of 7 segment display and buttons used to change the settings.
  • Energy saving feature such as sleep or economizer function where the set temperature will be automatically adjusted according to the duration that has elapsed.

The typical simple mechanical control that is used in older Packaged Terminal Air Conditioner units.

Newer units have electronic control option that have more feature such as energy saving mode and 7 segment display.

Some manufacturers may have more complicated control system that is able to link up all the units and control them at a central control on top of the individual control that are available at each of the unit. The central controller may be in the form of a personal computer or a touch panel.

Choosing The Capacity Of PTAC

In selecting the BTUH of the PTAC, a typical rule of thumb is to measure the length and width of the room. Multiply them together and match it to the recommended chart listed below. As an example, if the length of your room is 20 feet and the width is 15 feet, you will get a 20 X 15 square feet which is equal to 300 square feet. The BTUH needed based on this formula is 8000 BTUH.

NoSquare FeetBTUH Required
1100 to 1505,000
2150 to 2506,000
3250 to 3007,000
4300 to 3508,000
5350 to 4009,000
6400 to 45010,000
7450 to 55012,000
8550 to 70014,000
9700 to 1,00018,000
101,000 to 1,40024,000
Editorial Contributors
Alora Bopray

Alora Bopray

Staff Writer

Alora Bopray is a digital content producer for the home warranty, HVAC, and plumbing categories at Today's Homeowner. She earned her bachelor's degree in psychology from the University of St. Scholastica and her master's degree from the University of Denver. Before becoming a writer for Today's Homeowner, Alora wrote as a freelance writer for dozens of home improvement clients and informed homeowners about the solar industry as a writer for EcoWatch. When she's not writing, Alora can be found planning her next DIY home improvement project or plotting her next novel.

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Roxanne Downer


Roxanne Downer is a commerce editor at Today’s Homeowner, where she tackles everything from foundation repair to solar panel installation. She brings more than 15 years of writing and editing experience to bear in her meticulous approach to ensuring accurate, up-to-date, and engaging content. She’s previously edited for outlets including MSN, Architectural Digest, and Better Homes & Gardens. An alumna of the University of Pennsylvania, Roxanne is now an Oklahoma homeowner, DIY enthusiast, and the proud parent of a playful pug.

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