What is the Difference between an Air Handler and an Air Conditioner?
There are so many components in an HVAC system such that it is hard for most homeowners to know exactly which does what and how. For instance, not many homeowners can tell the difference between an air handler and an air conditioner.
So, what is the difference between an air handler and an air handler? And is the air handler part of the AC unit?
The function of an air conditioner is to cool indoor air by absorbing its heat and releasing it outside. On the other hand, an air handler pulls air from indoors and outdoors (ventilation) and delivers it to the cooling or heating coils and afterwards supplying it to the house.
Simply put, ACs remove heat from indoor air and release it outside while air handlers move indoor air through heating or cooling coils and then supply the heated or cooled air to indoor spaces. ACs have an inside and outside unit while air handlers are single units located indoors.
An air handler is not part of the AC system. In fact, an air handler can be connected to an air conditioner or heat pump to form a complete HVAC system. Air handlers are not standalone units hence need an AC or heat pump to actually heat and cool the air.
That reminds me that there also lots of folks who cannot also tell the difference between AC and HVAC. AC is simply air conditioner while HVAC stands for heating, ventilation and air conditioning. More on that in this post.
ACs don’t necessarily need an air handler. An air conditioner can work with an air handler or a gas furnace. Since air handlers are fully electric, it is expensive heating a house with an air handler hence most air conditioners are connected to furnaces.
So, what is the difference between an air handler and a condenser?
A condenser is the outside unit of an AC where the heat absorbed indoors is released to the surrounding air by a refrigerant. On the other hand, an air handler is located inside the house purposely to pull air from the indoor spaces for cooling or heating and afterwards deliver it back through air ducts.
Air Handler vs Air Conditioner
To understand how different air handlers are from air conditioners, you must first understand how they work.
How an Air Conditioner Works
When comparing air conditioners and air handlers, most of us actually refer specifically to central air conditioners. But as you already know, there are other types of air conditioners like mini-splits, window and portable air conditioners.
Air conditioners have an outside unit and an inside unit. The outside unit houses the compressor and the condenser coil while the inside unit houses the evaporator coil.
The 3 main components are connected together using copper pipes. Evaporator and condenser coils are both heat exchangers.
Inside the evaporator coil, heat from indoor air is absorbed while inside the condenser coil, the heat is released to the surrounding air. The heat exchange is effected by a chemical known as a refrigerant.
The refrigerant enters evaporator coil inside the house as a very cold liquid. Depending on whether the AC is connected to an air handler or furnace, the fan will pull hot air from the house and move it across the coil.
The refrigerant will absorb heat from the indoor air and therefore cool it. Cooled air is then supply back to the house using the supply air ducts.
After absorbing heat from the air, the refrigerant will vaporize, leave the evaporator and enter the compressor.
Inside the compressor, the pressure of the refrigerant gas will be increased, a process that also dramatically increases its temperature. It is important for the refrigerant temperature to be increased so that heat can be transferred to the outside hot air.
Remember: In heat exchange, heat is transferred from a point of high concentration to a point of low concentration.
From the compressor, the superheated refrigerant enters the condenser coil. As it moves through the coil, the condenser fan blows cooler air over the coil which absorbs heats from the refrigerant and dissipates it to the outside air.
By the time the refrigerant is exiting the condenser coil it will have lost so much heat that it will have condensed back to a liquid and ready to go back to the evaporator coil for more cooling.
As you can see, the function of a condenser is very similar to that of the air handler but they are quite different.
A condenser is found outside the house while the air handler is located inside the house. Secondly, a condenser is a heat exchanger (removes heat from the refrigerant) and releases outside while an air handler merely moves air from the house to the cooling/heating coils and back to the house.
How an Air Handler Works
As I have mentioned, an air handler works with either an air conditioner or heat pump. Its most important part is the blower and that is why some folks also call it a blower.
However, a complete air handler consists of a blower, evaporator coil, electric heating strips, and air filter among other smaller parts. It is a metallic box which looks like a furnace and installed somewhere in the attic, basement or closet.
Air handlers are connected to the return and supply air ducts. Return air ducts are the ducts that bring hot or cold air from the house for heating or cooling. Inside the house they terminate at the return air vents.
Supply air ducts are the ducts that carry cooled or heated air from the air handler to the house. As you can see, the house, air handler and ductwork form a loop that works all the time whether the house is being cooled or heated.
When the thermostat calls for cooling or heating, the air handler kicks in and its blower starts sucking air from the house through the return air ducts. Depending on whether the air needs to be cooled or heated, it is moved across the cooling or heating coil where heat exchange takes place.
Before heating or cooling, the air is first passed through a filter where dust, lint, pollen and other impurities are removed. The air conditioned or heated air is then supplied back to the house through the supply air ducts.
Air handlers are also responsible for ventilation. Ventilation is the deliberate process of replacing stale indoor air with fresh outdoor air.
Ventilation is an important aspect of HVAC. For your comfort, not only do you want the air cooled/heated but you also need it to be fresh.
Recycling the same air over and over again can make it stale. Breathing, cooking, cleaning and other such activities lowers the quality of indoor air and hence the need for ventilation,
Ventilation can be achieved by simple actions such as opening doors and/or windows (natural ventilation). However, opening windows and doors will lower the efficiency or your cooling and heating systems.
As such, the air handler is connected to a vent which delivers fresh air from outside. Therefore, the air cooled by the air handler is from both the indoor air and outdoor air. The air is mixed, air conditioned and then supplied to your house.
But why not just draw 100% fresh air from outside and exhaust the stale indoor air? Well, that would be very expensive.
Assuming that it is during summer, the air outside although fresh would be quite hot. On the other hand, the indoor air will be stale but just warm. If you decided to draw 100% of air from outside, the system would need to work harder to cool it.
The harder a system works the less efficient it is and the more you pay in energy bills. Mixing the indoor air with outdoor air slightly lowers its temperature thereby saving cooling and heating costs.
Air Conditioners vs Air Handler vs Heat Pump
Most folks also have a hard a time understanding the difference between a heat pump and an air conditioner. After all, the 2 systems look the exact same way.
The difference between an air conditioner and a heat pump is that an air conditioner can only cool the house while a heat pump can cool and heat the house. ACs are mostly paired up with gas furnaces for heating while heat pump use air handlers for auxiliary heating.
Note: Heat pumps and air conditioners work the exact same way when cooling the house. Only the heating phase is different.
The type of heating offered by air handlers is in form of electrical resistance heating. That is good enough for heat pump’s auxiliary heating but not air conditioners.
Heating a whole house with electric power for a whole winter would be very expensive compared to a natural gas-powered furnace. That will always be the case unless electricity prices fall dramatically while those of natural gas go up.
Different from an air conditioner, a heat pump has a reversing valve that reverses the direction of flow of the refrigerant when being used to heat the house. That way, the heat pump can extract heat from the outside air and use it to heat the house.
A very cold refrigerant is pushed through the condenser coil outside the house where it absorbs heat from the cold air (it is possible) and then evaporates and flows out to the compressor.
Inside the compressor, the gas is compressed to increase its pressure, a process that also increases its temperature. A high-pressure and hot refrigerant gas is then delivered to the evaporator coil inside the house.
As I mentioned, the heat pump will be connected to an air handler. The air handler’s blower pulls cold air from the house and moves it across the coil.
The air absorbs heat from the refrigerant and that is how it gets heated. The heated air is then supplied back to the house.
When temperatures outside drop below 35/40 degrees, the heat pump can no longer extract heat from the air. At that time, auxiliary heating will come on in your thermostat.
When the auxiliary heating comes on, the air electric heat strips will be activated to complement the heat pump. Auxiliary heat will go off once the temperatures outside improve.
And basically that is the difference between an air conditioner and an air handler. Apart from that, I also hope that you now know the difference between an air conditioner and a heat pump, difference between heat pump and air handler and also the difference between an air handler and a furnace.