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Window AC vs Heat Pump

Deciphering the differences between the many types of air conditioners is a nightmare. Every type is installed differently, has different power levels, and works in different types of properties.

That’s why we put together this series of articles to help you pick the right air conditioner for your home. This article covers the difference between a window AC and a heat pump.

What’s the difference  between window AC and heat pump

The difference between a window AC and a heat pump is that a heat pump is a higher-capacity air conditioning system that also offers heating and is permanently installed. A window AC does not have the ability to heat your home and sits in an open window.

A window air conditioner is installed in an open window. It is generally lower capacity than more permanent types of air conditioning. As a result, it is popular in smaller apartments that may not have permanent aircon.

A heat pump is a special kind of air conditioning that can be reversed to heat your home. Most air conditioning systems act as a conveyer belt for heat, which is carried out of your home via a chemical called refrigerant. 

Air conditioning exploits differences in pressure to change the temperature of the refrigerant, allowing it to cool your home and then transfer heat to outdoor air.

A heat pump has two compressors that allow it to switch the balance of pressure in order to carry heat into your home during the winter.

Cooling Capacity

A heat pump has a much higher cooling capacity than a window AC. A heat pump produces 10,000 – 24,000 BTUs of cooling power while a window AC produces 8,000 – 12,500 BTUs.

The difference is stark when we consider the upper extremes of both types of AC. The most powerful heat pumps for residential use produce 60,000 BTUs of cooling power. That’s enough to cool the very largest homes.

By contrast, the most powerful window AC can offer 24,000 BTUs of cooling, enough for an apartment with a few rooms. 

BTUs are a measure of thermal energy. It’s the amount of energy needed to change the temperature of one kilogram of water by a single degree Fahrenheit. 


Heat pumps are much more expensive than window ACs. The cost of a heat pump is $3,500 – $7,000 including installation costs. A window AC has no installation costs and is $200 – $600. 

The difference in price is so huge because a heat pump is a much more substantial piece of machinery. Smaller units work a lot like normal air conditioners but the larger ones are installed into the ground so they can draw on geothermal energy.

Energy efficiency

Heat pumps are much more energy efficient than window ACs. Window ACs lose power to the outside air and to leaks around the connection between the unit and the open window frame.

A heat pump is usually connected through the home’s infrastructure so there is no need to compromise the building’s seal against outside air. 

Should I buy a window AC or a heat pump?

You should buy a heat pump over a window AC if you need to cool a larger property. Heat pumps are also a sensible choice if you want heating in the winter as well as cooling the summer.

Heat pumps and window ACs are designed for different types of property. A heat pump can cool the very largest residential spaces while window ACs are best used in apartments.

The upfront cost of heat pump is far greater than you’ll pay for a window AC. But you’ll get much better energy efficiency. If you’re cooling a larger space, you’ll save a lot more money on electricity bills in the long run.