You depend on your air conditioning to keep your home safe and comfortable during the extreme heat and humidity. However, what isn’t so well known is that HVAC systems may not operate effectively in extreme temperatures. Learn the basics of how your AC works, how extreme temperatures affect the system, and what you can do to easily prepare your system to better handle extreme summer weather.
AC Basics: Heat Transfer
Before jumping into how extreme temperatures affect your air conditioner, it’s important to take a step back and learn exactly how your AC keeps your home cool. Your AC unit doesn’t create cold air in the way that a furnace creates heat. Rather, it absorbs heat from the air moving through the system, making it cooler. Under ideal circumstances, the air coming from your central or ductless air conditioning system is about 20 degrees cooler than the air in your home.
The system uses refrigerant to absorb the heat inside, but it has to do something with it once it’s absorbed. It’s the job of the outdoor condensing unit to vent that heat to the outside air. To make all of this work, the refrigerant goes through pressure changes, which then changes its temperature. Inside your home, the system restricts refrigerant flow into the evaporator coil through the use of the expansion valve. This restriction allows the refrigerant to expand, which drops the pressure, causing it to get cold so that it can absorb heat. Think about how a can of compressed air gets cold when you use it.
The refrigerant then circulates to the condensing unit outside. In contrast to the expansion valve inside restricting the amount of refrigerant moving into the evaporator coil, the condenser compresses it together before moving into the condensing coil. This compression causes the refrigerant to get hot and allows the air outside to absorb that heat before the refrigerant moves back into your house.
The second law of thermodynamics is what describes why this works. Heat always transfers from hotter air to colder air. This means that the refrigerant must become cooler than the air flowing through the system to absorb heat. It also means that it must become hotter than the air outside to vent the heat. It’s this fundamental understanding that describes why extreme heat will affect your AC in the following ways.
1. Limits Heat Transfer
One of the first things to consider about extreme heat is that it limits the amount of heat transfer the refrigerant can perform. The fundamentals of that second law of thermodynamics show us that the greater the temperature difference between two things, the more heat transfer occurs. Conversely, when they’re closer in temperature, they transfer less heat. That means that the hotter the outside air that’s moving through the condensing coils is, the less heat it can absorb without the coils becoming hotter. The system can only get so hot because heat is a function of pressure, and it can only generate a limited amount of pressure. The less heat transfer that occurs outside, the less efficient the system becomes.
2. Increases Compressor Strain
The compressor is responsible for creating the pressure inside the condensing coil to make the refrigerant hot enough to initiate the heat transfer happen. When the temperature outside increases over 100 degrees Fahrenheit, the compressor has to work harder to achieve the desired heat transfer. The failure to transfer the proper amount of heat at the condensing coil creates a perpetual issue where the refrigerant is now warmer than intended throughout the rest of the cycle. Because of this, the compressor experiences more strain to try to increase the pressure and temperature by the intended amount. This extra strain on the compressor will wear it more quickly and cause it to fail prematurely.
3. More Household Radiant Heating
Extreme heat is often accompanied by a lot of sunshine, which is part of what creates the heat. That means that your home will experience greater radiant heating, raising the temperature inside your home. Your already taxed system will have to work harder to keep your indoor temperature down at your desired level.
4. Increased Energy Consumption
An air conditioner is not like smaller appliance that use a set amount of electricity when it runs. Rather, the energy consumption is directly tied to the strain on the system. More strain on the system creates additional electrical resistance. When electrical resistance increases, it needs more electricity to push through the circuit and make things run properly. When combined with longer and more frequent cooling cycles, the increased electrical resistance causes your energy consumption to spike.
5. Component and System Failures
Because of all of the added strain we’ve already discussed, your system is more likely to fail during periods of extreme heat. These failures could be individual components like the condensing contactor or capacitor. It could also be a complete system failure, which usually comes down to some form of leak or a failure at the compressor. In many cases, these issues during extreme temperatures are avoidable if you simply understand how to prepare for them in advance.
Easing AC Strain During Extreme Temperatures
There are a few ways you can ease the strain your system experiences, even on extremely hot days. First, think about how much relief a little shade provides on extremely hot and sunny days. You can provide the same relief for your air conditioner by providing some shade during the hottest parts of the day. As you look to construct some kind of shade, you need to ensure that it still has enough room to circulate the outside air. The rule of thumb is at least 2 feet around all sides of the condensing unit, and about 5 feet above it. If you don’t want to construct something permanent, you can even use something like a shade sail or an umbrella. The goal is simply to keep the direct sunlight off the unit.
Next, keep the system maintained and clean. Neglecting maintenance reduces the efficiency at which the system runs, which adds to the strain while operating at normal levels. This can be the difference between it keeping up on the extreme days versus breaking down.
Finally, gently clean your system regularly. The humidity around the Tampa area carries with it excess contaminants like dirt, pollen, and salt that will all settle on the condensing coil. This both restricts the airflow through the coil and increases the risk of corrosion. Simply use a garden hose without a nozzle on it to rinse off the contaminants. Ideally, plan to do this at least two or three times over the summer to minimize the effect of the high salt content in the air.
Home and property owners around Tampa know that when they want quality household services, they call Protek Roofing, Heating, Air & Solar. Our team not only provides expert heating and air conditioning repair, maintenance, and installation but also indoor air quality solutions and roofing and solar services. Call to schedule your AC maintenance or repair appointment with one of our trusted technicians today.