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On, Auto, and Circulate: Which Is the Best Thermostat Mode?

September 4, 2023
On, Auto, and Circulate Which Is the Best Thermostat Mode

Thermostats often come with many features and settings that homeowners don’t fully understand. Some only care about learning the temperature setting button, as they deem it the most important in keeping their home comfortable.

However, the other functions are just as important, especially the fan modes. They dictate how air is circulated in your home and affect other factors like energy usage, air quality, and temperature distribution.

In this article, we’ll discuss the three different fan modes you’ll find in your thermostat, their advantages and disadvantages, and which mode is best for you.

Which thermostat setting should I use?

Which thermostat setting should I use

The auto mode is commonly recommended, as the cost of always running the fan can be too high. It’s also the best mode to use during summer as it keeps humidity inside the room at a manageable level.

However, with the introduction of circulate mode, it’s becoming a popular mode choice during spring ang fall, as it allows you to enjoy the benefits of both on and auto settings.

That said, choosing the best setting is something that you can only decide for yourself, as we all have different situations and things to consider. 

Although auto and circulate modes are what most people suggest, there are some instances when it’s best to use on mode.

Here are some instances when you need to keep the fan running:

You’re suffering from various allergies

Keeping the fan running improves the overall air quality in your home, so the on setting is best for people who are suffering from various allergies, especially those that can be triggered by dust.

It’s also the recommended setting for people who have severe asthma as auto and circulate modes may provide more stagnant and stuffy air.

You have elderly people in your house

Using the on setting can provide a more comfortable environment for elderly people. Hence, it’s advised when you live with your parents or grandparents.

The constant use of the fans provides a more filtered air, while the constant flow of air eliminates stuffiness inside the home, leading to a more comfortable living environment.

You have a lot of guests

When there are more people present in your home, the air within can quickly become stale and stuffy. Using on mode and constantly running the fan helps circulate air throughout the space and maintains a comfortable environment for all guests.

You can also expect the indoor temperature to increase because of the number of people inside. Running the fan’s on mode helps maintain a consistent temperature by constantly circulating cooled air.

You’re cleaning the house

As we’ve said earlier, keeping the fan running can help absorb dust and circulate more filtered air. This makes on mode an ideal setting when you’re cleaning the house and a lot of dust is floating in the air.

What is a circulation fan?

What is a circulation fan

A circulation fan in an air conditioning (AC) unit is responsible for moving air throughout the room being conditioned.

The primary function of the circulation fan is to draw in air from the return ducts and then push it through the heating or cooling components of the AC unit. 

The circulation fan is often controlled independently from the compressor or heating elements. 

This allows the fan to operate even when heating or cooling is not actively required, providing continuous air circulation and promoting better air distribution throughout the room.

The circulation fan can mostly be controlled through the thermostat and have three different settings available: on, auto, and circulate.

Different Thermostat Modes on an AC

Different Thermostat Modes on an AC
ProsCons
On• Consistent air circulation

• Improved air quality

• Even temperature in the room

• Recommend when cleaning

• Increased energy consumption

• Air filter wears out faster

• Can strain the AC

Auto• Energy efficient

• Noise reduction

• Reduced wear and tear on air filters

• Efficient dehumidifying

• Uneven temperature

• Less air circulation

• Potential wear and tear on fans

• Less air filtration

Circulate• Improved air quality

• More energy efficient than on setting

• Even temperature in the room

• Potential wear and tear on fans

• Less effective air circulation and temperature distribution than on setting

What is circulate mode on a thermostat?

What is circulate mode on a thermostat

Circulate mode on a thermostat runs the fan in cycles. The fans run about 35% of the time in this mode, with around 20 minutes of running time every hour.

This mode aims to circulate the existing air throughout the room and keep the temperature consistent. That said, it’s still relatively less effective in circulating the air and maintaining an even temperature than the on setting.

Under this setting, you can also notice better air quality inside the room. The frequent running of the fan helps filter the air, reducing the dust and allergens in the air. 

Circulate mode is also relatively more cost-efficient than the on setting, as the fans are not constantly running.

The only drawback is that this poses higher chances of wear and tear in the fans than in the on setting. The repeated turning on and off of the fan can actually strain it more than when it’s constantly running.

The circulation mode setting is a relatively new addition to AC units, so it’s only often seen in newer units. Most often than not, you’ll only find on and auto settings.

What is the on setting on a thermostat?

What is the on setting on a thermostat

The on setting on a thermostat refers to a mode where the AC unit’s fan runs continuously, regardless of whether the heating or cooling components are actively running. 

This means that the fan will constantly run 24/7 until you change the setting.

This setting helps circulate air throughout your home, even when the target temperature has been reached and no additional heating or cooling is required. 

Since the fan is constantly running, cold and hot air is also distributed evenly throughout the room. This means hot or cold spots inside the room are unlikely to occur.

Additionally, you get the best air quality out of the three settings when you set your thermostat to on. This is because the air being blown out by the fans consistently passes through the air filters, creating more dust and allergen-free air.

This is the recommended setting when you’re cleaning your room, as the AC unit will pull the air to the filter and blow much cleaner air.

That said, you’ll likely have to change your air filters more frequently in this setting than in circulate and auto modes. Since the AC absorbs and circulates air nonstop, the air filters naturally trap more dirt.

This setting can also strain the AC unit as a whole in the long run, as it is constantly running and doesn’t have time to rest.

Moreover, this uses far more energy than the other two settings, leading to increased electric bills. It costs about $50 more a month to run the AC in this mode.

What is the auto setting on a thermostat?

What is the auto setting on a thermostat

The auto setting in AC units refers to a mode of operation where the system’s fan and compressor are controlled automatically based on the temperature settings and the current conditions inside the room.

This means the fan only turns on when the AC senses that the room temperature is lower or higher than intended.

Among the three settings, auto is the most cost-efficient, as the fan only turns on when the cooling and heating system turns on. This means the AC uses less energy and, thus, costs less to run.

This also produces the least amount of noise, as the fans barely run. It’s best for people who are quite sensitive to noise.

Additionally, it’s efficient when it comes to controlling humidity in the room. While the fans are off, the moisture droplets from the coils are being drained outside, instead of being blown back to the room.

The drawbacks, though, are the higher possibility of uneven temperature inside the room, less air circulation, potential wear and tear on the fan, and less air filtration.

Since the fan only turns on during cycles, it’s unable to distribute the air throughout the room more evenly. This is why certain spots can be a lot cooler or hotter than others.

There’s also significantly less air circulation, so it may be less comfortable than when the AC is turned to on or circulate mode. 

This also means the air inside is less filtered, which can cause irritation to people with various allergies, like allergic rhinitis and dust mite allergy. 

Lastly, the risk of wear and tear on the fans is higher in this setting. This is because the fan frequently starts and stops during the day, straining its motor.

FAQs About Circulation Fan Settings

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