In most cases, air conditioners only have one speed (though some have variable speed settings to improve energy efficiency). Lowering the temperature too much causes your air conditioner to operate longer, causing more wear and tear on it as well as higher utility bills.
A common rule of thumb is that most models can function properly only above 68 degrees Fahrenheit. Any lower temperature will result in the system freezing up. In addition to a frosty refrigerant, the piping and coils could also become covered with ice.
In short, the 20-degree rule of air conditioning states that you should always keep your AC unit at no more than 20 degrees lower than the outside temperature. It means that, if the outdoor conditions are at 95 degrees, you should set your thermostat at no less than 75 degrees.
The lowest outside temperature at which to run your AC is typically around 60-65 degrees Fahrenheit. At temperatures below this range, your air conditioner might not operate efficiently, causing increased energy consumption and potential strain on the system.
This is more of a personal question, as different people feel comfortable at different temperatures. Since 72 degrees is generally agreed upon to be an ideal indoor temperature, most people would probably still feel comfortable setting their AC units slightly higher than this, perhaps at around 75.
If it's just you and your spouse, you may be fine with the temperature set at 75-77. But if you have kids and pets running around, or you're cooking and using your oven, these things can all raise the indoor temperature noticeably. So, you might find a temperature setting in the 72-74 range more comfortable.
For many of us, 70 degrees is the ideal indoor temperature, but when it is close to 100 degrees outside, your AC unit will be working quite hard to meet these expectations. Consider setting your thermostat at 75 degrees to 80 degrees in your home if the outside temperature is approaching triple digits.
Best AC Temperature Settings While You Are Home
As you consider the most comfortable room temperature for your lifestyle and family, keep in mind that for each degree that you set your thermostat above 72 degrees, you can save up to 3% on your energy bill.
Do not set your thermostat below 70 degrees as it will not cool any faster and could freeze up the system causing more problems. Understand that there is generally a 20 degree difference between indoor air and outside temperatures.
In the summer, experts say the thermostat for your air conditioner should be set to at least 78°F during the day when people are at home. That setting is designed to help people avoid high energy bills in the summer. The lower your thermostat setting, the higher your bill.
WHAT SHOULD I SET MY AC TO AT NIGHT? According to the Cleveland Clinic, the recommended thermostat setting for nighttime is between 60°F and 67°F. 3 Setting your AC within this range can help maintain a comfortable sleeping environment.
When the AC temperature is too low, between 60-67 degrees F (15-19 degrees C), the evaporator coil inside the unit can get excessively cold. If the humidity in the room is high, condensation can accumulate on the coil, which may lead to the formation of frost or ice.
According to the Department of Energy, you can save about 10% a year on energy costs just by setting your thermostat 7 to 10 degrees higher or cooler than normal for 8 hours a day.
For example, HVAC specialists recommend setting your thermostat no lower than 20 degrees the outside temperature. Suppose the outdoor temperature in your area is a blistering 90 degrees Fahrenheit. It's probably best to keep your thermostat between 70 and 80 degrees Fahrenheit to prevent stress on your unit.
But setting the thermostat really low doesn't increase your air conditioner's cooling capacity. “People think, 'If I make the thermostat set point 60, I'll get more cooling than a set point at 70,' but that's not correct,” Liu said. “You get the same amount of the cooling.”
Frost or Ice on Copper Lines
When refrigerant levels are not in balance, it can cause the refrigerant to become too cold and restrict airflow. Restricted airflow places tremendous strain on your air conditioner and can cause your evaporator coil to freeze up and stop working.
Even in normal circumstances, turning a thermostat down too low is not a good idea: the compressor will run longer without improved cooling. Trying to utilise this to compensate for an air conditioner can no longer chill the house as effectively as it should be, putting more load on an already faulty system.
Set a reasonable temperature: HVAC professionals strongly recommend never setting the thermostat lower than 68 degrees in the summer. To balance comfort and energy efficiency, the Environmental Protection Agency recommends setting your thermostat to 78 degrees when you're at home and awake.
Sometimes, when the room temperature doesn't match the thermostat setting, the problem could be dirt buildup on its interior parts. A dirt coating around the inner components may create excess heat and cause the thermostat to give the wrong readings.
Choosing the Best Temperature for Your Air Conditioner
You can also reduce your energy costs significantly by raising the temperature while you are at work, away from home, or asleep. For the greatest savings, consider setting your thermostat to: About 78 degrees while you are at home.
Setting the thermostat below 72 degrees while using an air conditioner can cause the unit to work harder than necessary, leading to higher energy bills and potential damage to the appliance.
To maintain a comfortable indoor environment during the summer, the American Society of Heating, Refrigerating & Air Conditioning Engineers recommends a range of 73 to 79 degrees Fahrenheit. On scorching hot days, you may want to adjust your thermostat toward the higher end of that range.
What should my AC be set at if it's 90 degrees outside? If the outdoor temperature is 90 degrees, it's recommended to set your thermostat between 75-78 degrees.
According to ENERGY STAR, a division of the U.S. Environmental Protection Agency, 78 degrees Fahrenheit is the most cost-effective AC setting during the summer months. 1 And that's just the recommendation for when you're at home.
During heat waves, experts, including utility companies, recommend keeping your thermostat no more than 20 degrees cooler than the outdoor temperature. For instance, if it's 100 degrees outside, aim to set your thermostat to at least 80 degrees.