The Ultimate Window Heat Pump Guide

Window Heat Pumps
The Ultimate Window Heat Pump Guide 4

For all the talk about swapping out our fossil fuel furnaces for heat pumps, there are millions of people for whom that is not a viable option. These are people who either don’t own their own homes or don’t control their own heating and cooling sources because they live in an apartment or condo complex.

For those people, a window heat pump may be the answer. They represent a cost-effective, energy-efficient substitute to conventional air conditioners, with the added benefit of being able to heat your home in the winter, as well as cool it in the summer. 

In this blog post, we’ll delve into the pros and cons of window heat pumps while providing advice on choosing the right model based on BTU capacity, SEER rating, noise levels, installation tips and more.

By the end, you’ll be well-equipped to decide whether a window heat pump is the right choice for your home’s heating and cooling needs.

How Does a Window Heat Pump Work?

A window mounted heat pump works in exactly the same way as a regular heat pump works except that, rather than having to be professionally installed by an HVAC specialist, it can be slotted into a window much like an air conditioner can. And it offers the added benefit f being able to heat your home in the winter as well as cool it in the summer.

So let’s start by looking at how a heat pump works.

When it’s in cooling mode, a heat pump acts just like an air conditioner. It takes the warm air from inside the home and moves it through some pipes containing a special gas called a refrigerant.

This refrigerant removes the heat from the air and expels it outside through a vent. The cooled air is then sent back into the room to make you feel more comfortable.

A reversing valve reverses the entire process when the heat pump is switched to heating mode. Then the heat pump absorbs heat from the outside air and pushes the warm air into your house.

The two most important concepts to grasp are:

  1. The heat pump isn’t actually heating the air, the way a traditional heater does with a furnace or electric coil. It’s  just moving warm air from one place to another. That makes heat pumps much more efficient than traditional heating appliances.
  2. Even when it’s cold out, the heat pump is still able to extract enough heat from the outside air to warm your room. Even in really cold places like Scandinavia or Maine, heat pumps are a perfectly viable way to heat a home.

Check out Heat Pump Basics here.

Window Heat Pump 1
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Advantages of a Window Heat Pump

So now that we’ve figured out how a heat pump works, let’s look at the specific advantage of a window heat pump.

Regular heat pumps are typically located just outside the home, with the warm or cool air pumped into the home through either ducts or “heads” such as mini splits. They usually have to be installed by an HVAC professional. And even installing the cheapest “ductless” system can cost many thousands of dollars. 

It’s certainly not the kind of expense you would be willing to make if you didn’t own the home, for example. Nor is it the kind of heating/cooling system you could take with you if you decided to move.

A window heat pump is a much cheaper, more portable, relocatable solution that is ideal for the 36% of Americans who currently rent their homes. 

Here are some of the advantages to using a window heat pump:

1. Eco-Friendly Solution

The use of electricity instead of fossil fuels makes these devices more environmentally friendly than other heating options such as gas or oil-fired furnaces.

2. Versatility

A single unit capable of providing both heating and cooling makes it a great choice for those who want to simplify their climate control needs.

3. Energy Efficiency

Heat pumps are known for their high energy efficiency ratings, which means they consume less electricity compared to other HVAC systems. This results in lower utility bills and reduced carbon emissions.

4. Space-Saving Design

he compact size of window heat pumps makes them perfect for small living spaces like apartments or individual rooms within larger homes.

5. Easy to Install

Although they’re heavy, window heat pumps do not require any specialized skills to install. Anyone with a few muscles can lift one into place, turn it on and be comfortable within a few minutes.

Disadvantages of a Window Heat Pump

Window heat pumps aren’t for everyone. Here are a few reasons why you might not consider buying one for your home.

1. Higher Upfront Cost

While there’s no doubt that, compared with a professionally installed ducted or ductless heat pump system, a window heat pump is a much cheaper alternative. However, compared with a traditional window air conditioning unit, a window heat pump is likely to be more expensive. Window heat pumps cost anywhere from $500 to $1,100 brand new, when you can get an inexpensive air conditioner for around $200.

Of course, you’re getting two appliances in one when you consider that a window heat pump keeps you warm in wintertime, as well as cool in the summer. And the higher efficiency means that the running costs will be lower. But the upfront cost of purchasing a unit will be higher than for a window air conditioner.

2. Smaller Capacity

A window heat pump is not going to heat or cool an entire house. They’re great for apartments, mobile homes, tiny houses and single rooms, but don’t expect one single unit to do much more than that.

3. Noise

Just like a window mounted air conditioner, a window heat pump has a compressor and a fan built inside the appliance. So there is bound to be a little more noise than with a regular heat pump, which has those things outside the home. 

You can expect your window heat pumps to emit a noise that ‘s comparable to the level of a regular conversation in a restaurant or an office. Not exactly silent, but hardly deafening either.

4. Less Effective in Extreme Cold

While most split system heat pumps work pretty efficiently down to 17 F, the effectiveness of window heat pump units tends to drop when the temperature goes down below freezing (32 F or lower.

5. You Lose Your Window

Let’s face it, we have windows in our homes for good reason. Fresh air, sunlight, the ability to see outside are all great benefits to having windows. I always feel the house “brightening up” when we remove our window air conditioners in the fall. Having a big hunk of metal blocking the view year-round may not be everyone’s cup of tea.

Check out the Gradient Comfort for a Window Mounted Heat Pump that doesn’t block your window

Features to Look for in a Window Heat Pump

To fully benefit from the advantages offered by window heat pumps, it’s essential to select the right unit based on your specific requirements and ensure proper installation.


Getting the sizing right for your window heat pump is a crucial first step. BTU is the standard unit used to measure the size of a heat pump in the US, which is weird because BUT stands for British Thermal Units. Tonnage is also used occasionally (one ton equals 12,000 BTUs), but we’re going to stick with BTUs for the purposes of this article.

A good rule of thumb for determining what size window heat pump you need is to take the area of the room and multiply it by 25. So a 10 foot x14 foot room would be 140 square feet. Multiplying that by 25 would mean you’ll need a minimum of  3500 BTUs.

There are other factors to consider, including ceiling height, insulation, shade and sun. Here is an article that tells you all you need to know about heat pump and air conditioner sizing.

Efficiency Rating

Just about any window heat pump is going to be more efficient than a conventional air conditioner. But that doesn’t mean you should ignore efficiency ratings. There are two ratings for measuring the efficiency of a heat pump – one for cooling and one for heating.

For cooling efficiency, you should check out the Seasonal Energy Efficiency Ratio (SEER) for its cooling functionality. Higher the SEER, the more efficient an air conditioner is. For its heating performance, the measurement that’s used is a Heating Seasonal Performance Factor (HSPF). An HSPF of 9 or higher is considered highly efficient, 

Timer Function and Mobile App

Any efficiency can be improved upon by only using the appliance when you actually need it, so a built-in timer, which can turn your heat pump on or off according to your needs, will be a welcome addition. 

Many window heat pumps also come with an IR remote control, which allows you to also use a smart AC controller to schedule exactly when your heat pump should turn on or off.

You can even control your window heat pump with your phone, changing the temperature and choosing which mode it’s in while you’re on your way home. It’s like having a remote that works no matter how far away you are – so cool! (or warm!)

Air Filters

All window heat pumps come with air filters and keeping those clean is an important part of their maintenance, To that end, having a machine that supports washable air filters is a big advantage.

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Installation Tips for Window Heat Pumps

Proper installation is essential to ensure optimal performance from your window heat pump. It can help avoid common issues like poor sealing or incorrect placement within windows. In this section, we’ll cover some useful tips for installing your new unit correctly.

Preparing the Installation Site

Before you begin installing your window mounted heat pump, it’s important to choose a suitable location that meets certain requirements:

  • The window should be strong enough to support the weight of the unit and have an electrical outlet nearby.
  • Choose a window in that’s away from other heat sources to maximize cooling efficiency.
  • If possible, select a window on a shaded side of your home with good air circulation around it.

You may also need additional tools and materials such as brackets, screws, foam insulation strips, and weather stripping depending on the specific model you’ve chosen. Be sure to consult the manufacturer’s instructions for any special requirements before starting installation.

Sealing Gaps Around The Unit

To prevent drafts and maintain energy efficiency during both heating and cooling modes, proper sealing around your window heat pump is crucial. Here are some steps you can follow:

  • Clean the area: Before attaching any seals or insulation material to your window frame or sill, make sure they’re clean by wiping them down with a damp cloth first so that adhesive materials will stick properly.
  • Add foam insulation strips: Apply self-adhesive foam insulation strips along all four sides of where you plan on positioning your unit within its opening in order to create an effective seal against cold air and drafts. You can find these strips at most home improvement stores.
  • Install weather stripping: To further improve your window heat pump’s heating efficiency, add weather stripping along the top and bottom edges of the unit where it meets your window frame or sill. This will help prevent warm air from escaping during heating mode and cold air from entering during cooling mode.

Window Heat Pump FAQs

Are Window Heat Pumps Worth It?

Yes, window heat pumps are worth it for people who are concerned about climate change and energy efficiency. They provide both heating and cooling functions in a single unit, reducing the need for separate systems. Additionally, they operate on electricity rather than fossil fuels, helping to decarbonize homes.

Do Window Heat Pumps Work in Cold Climates?

Window heat pumps can work effectively in cold climates but may struggle when temperatures drop below 32°F (-6°C). In such conditions, supplemental heating sources might be necessary. Some models come with low-temperature operation features designed specifically for colder regions.

What Are Some Downsides to a Window Heat Pump?

The main downsides of using a heat pump include higher upfront costs compared to conventional window air conditioners and potential performance issues during extreme temperature fluctuations. Regular maintenance is also required to ensure optimal functioning and energy efficiency throughout its lifespan.

Final Thoughts

Window heat pumps are a great way for homeowners to decarbonize their homes while still enjoying the comfort of heating and cooling systems. They work by using heat exchange technology to transfer warm air from outside into your home during the winter months, and reversing the process during summer.

To select the right window heat pump, it’s important to consider factors such as BTU capacity, seasonal energy efficiency ratings (SEER), noise levels, and installation requirements. Proper maintenance is also key in ensuring optimal performance.

Check out some other Climate Friendly Appliances:

The pros and cons of heat pump dryers

Can the Gradient Window Heat Pump Save the World?