On a hot summer day, there are few appliances more useful than the window air conditioner. These miracles of engineering move heat from inside your home to the outside, cooling the air inside to make it more comfortable. These devices pump heat from one side to another, shifting the heat to the outside and circulating wonderful cool air inside. And they do this in a remarkably small space, without having to knock holes in the wall. So, how do these miracles of cool work? Fundamentally, a window AC unit is a pump, one that shifts heat instead of water. It does this by using a chemical that turns from a liquid into a gas with a relatively small shift in pressure. Called a phase transition, this process is at the heart of how window AC units work: by repeatedly pressurizing and then releasing this chemical, the window AC unit moves energy from one side to the other. Combine this with a fan that circulates the air through the unit, and you get air conditioning. At the core of a window AC unit is a loop of pipe, usually copper, with a pump on one side and a small expansion valve on the other.

This loop has two radiators on it: one on the outside and one on the inside, which have fans behind them to push the air over them.On most modern units, this loop is filled with a coolant called R-410A, which is a mixture of two chemicals: difluoromethane (CH2F2) and pentafluoroethane (CHF2CF3). This coolant is used because if you compress it, it becomes a liquid. If you then release this pressure, it evaporates to become a gas, and the difference in pressure needed to go between the two states is fairly small. These two states are the mechanism that moves the heat from inside your house to outside. When the pump is active (which you can usually hear; it's the low-frequency rumble from a working AC), it's compressing the coolant so it becomes a liquid. This liquid passes through the outside radiator, where it sheds heat into the outside air. When it reaches the expansion valve, only a small amount is let through, so the pressure on the other side is much lower. This makes the coolant evaporate, which cools it down.

From there, it passes through the inside radiator, and the air passing over this is cooled. The coolant absorbs the energy (the heat) from the air inside the room, cooling it. The coolant then moves into the pump, where it is compressed again and pushed into the outside half of the loop, and the process repeats. The whole process is controlled by a computer that measures the temperature of the air being sucked into the unit and turns the pump on and off as required. Because the coolant takes time to pass through the expansion valve, the pump doesn't run all the time when the unit is cooling: when the pressure on the hot, outside part of the loop reaches a certain level, the controller turns the pump off until the pressure falls. As the coolant passes through the pressure valve, it evaporates and cools in the inside radiator, and you feel the cool air. That's why you don't feel an immediate rush of cool air when you turn on a window AC unit: the pump has to build up the pressure before the cooling can begin.

The cooling power of windows AC units is measured in British Thermal Units (BTU). This is a measure of how much energy (in the form of heat) the device can shift from one side to the other. Specifically, one BTU is the amount of energy it takes to heat (or cool) one pound of water by one degree Fahrenheit. The higher this number, the more energy (heat) the unit can move, and the larger the area it can cool.Most window AC units range from 2,000 to 25,000 BTU. However, most units over 15,000 BTU will require a dedicated 230V power line, like those used by electric dryers. coleman ac units for campersThis process of repeatedly compressing the mix uses a lot of energy, which is why window AC units are notorious power hogs, especially when the pump first starts. air conditioning unit plenum boxThat's why the lights sometimes flicker when a window AC unit turns on: The device is sucking down a lot of juice to get the pump started compressing the mix and beginning the cycle. hvac purge unit

But let's be honest -- that wonderful rush of cool, clean air on a hot day is worth the electricity bill. So, on a hot, sunny day, give thanks to the science of thermodynamics, the invention of the refrigeration cycle and the complex engineering that keeps you cool. Window and Wall Air Conditionerswall air conditioners To contact Appliances Connection with any questions on what Window and Wall Air Conditioners best fit your home, please call 800-299-9470.The cost to ship items varies by item, shipment and shipping option. Standard ground shipping transit time is 5-7 business days. Curb side delivery (also called freight or "LTL" shipping) is reserved for large, heavy, or oversized items like chandeliers, bathtubs, shower doors, etc. Items are palletized and loaded onto a large truck for shipment, and delivered to your curb by scheduled appointment. Transit time is 7-10 business days. * For exact shipping costs, add the product(s) to your cart and enter your zip code.

All offers pertain to the lower 48 states and do not include deliveries to Alaska, Hawaii or Canada. Learn more about shipping rates and policies Sign up today and activate a Common Questions about Window Air Conditioners Published May 27, 2010 | Updated August 5, 2015 A great way to beat the heat is by installing a window air conditioner in your home or office. Using individual air conditioners and heaters in your home can take the load off of your central heating and air conditioning system, providing you with significant energy savings over the course of a year. Here are some frequently asked questions about window air conditioners and how you can use them in your home. Shop Air Conditioners & Heaters ▸ Will window air conditioners work in any window?Window air conditioners are built to fit multiple window types, including those that open vertically or horizontally. Many window air conditioners include adjustable panels, which help them expand to fit and seal most window openings.

Be sure to measure your window and compare it to the air conditioner dimensions. What is a "SEER" rating?The SEER rating is a rating of window air conditioner efficiency. The higher the SEER rating, the more BTUs of cooling power your window air conditioner creates for every watt of power. SEER ratings are calculated by dividing the number of BTUs by the watts used per hour. How much energy does a window air conditioner use?To calculate your window air conditioner's energy use, divide the BTUs by the SEER rating. This gives you the watts per hour. Divide that by 1,000 to get kilowatt hours (kWh), which is probably how your electric company calculates your energy bill. You can then multiply the kWh by your power company rate to learn your costs per hour. For example, a 12,000 BTU air conditioner with a SEER rating of 10 and a cost of 25 cents per kWh would calculate as follows: 12,000 BTUs / SEER 10 = 1,200 W = 1.2 kWh 1.2 kWh x $0.25 = $0.30 per hour to run your window air conditioner.