Nest Thermostat Temperature Swing? (Possible Causes & Fixes)

Nest Thermostat Temperature Swing

Your Nest thermostat displays one temperature, the app shows another, and you feel like neither is correct. Sound familiar? No, you’re not going crazy.

A slight temperature difference between your home and the thermostat reading is perfectly normal. It’s typically due to a delay—called a temperature swing—that’s built into many HVAC systems. Thermostats have them, too.

Nest thermostats have a 2° temperature swing. This means your home’s temperature may feel 2° hotter or colder than what’s displayed on the thermostat. Nest waits to activate your HVAC system until the room temperature is roughly 1° warmer or cooler than the set temperature. This delay saves energy and prevents excessive wear on your HVAC system.

Understanding Temperature Swings

A temperature swing is also commonly known as the maintenance band, deadband, or temperature differential. It’s the temperature difference between the inside and outside areas of your house that determines how often your HVAC system runs.

The lower the temperature swing the more your system runs. Meaning, the temperature of your house and the thermostat reading will be closely matched much of the time.

The Importance of Temperature Swings

Many HVAC systems have a built-in delay for their protection. Constant starting and stopping are not healthy for the many moving parts of an HVAC system. It may shorten the system’s lifespan.

Nest provides an additional delay in the form of a temperature swing. It gives added protection, particularly for HVAC systems that don’t employ an automatic delay.

The delay from the temperature swing should only last a few minutes. Any longer, and Nest might be showing signs of faulty temperature readings.

Not only does a temperature swing protect your HVAC system, but it also saves energy. The system only turns on when the temperature is within the set limits of the temperature swing.

Nest Temperature Swing

Many thermostats allow the temperature swing to be adjusted. By default, Nest fixes the temperature swing at +/-1°F from the set point. This means there could be up to a 2° difference between the room temperature and thermostat reading.

For example, your temperature is set to 70°, which means the heat kicks on when the room hits 69°. The heat turns off when the room hits 71°.

Ideal Temperature Swing

For comfort purposes, our ideal temperature swing would be 0°. This ensures the temperature remains constant. However, this is not practical nor is it safe for the equipment.

Having a zero differential means the system runs in short, consecutive cycles, which we learned shortens its lifespan. The ideal cooling differential is between .08°F and 2°F, and the ideal heating differential is between .05°F and 1°F. These ranges ensure enough time between cycles.

Nest does the hard work for you by setting the temperature swing at a default temperature of 1°F. You won’t have to try and figure out the appropriate range for your cycle since 1° is well within the common limits.

Adjusting the Temperature Swing on Nest

Here’s the thing about temperature swings. If a zero differential gives the most comfort but is impractical, longer cycles will do the exact opposite. A longer cycle makes your HVAC system happy. But it might lead to more discomfort for the homeowner. In the winter, the difference between 68° and 70° is huge for some.

Most traditional thermostats offer the option of adjusting the temperature swing. Unfortunately, the temperature swing on a Nest is automatic. It can’t be changed through any settings on Nest itself.

This is a big complaint for some users, especially those who live in areas with temperature extremes. Waiting for the temperature to drop or raise 2° can lead to prolonged, uncomfortable temperatures.

However, there are some loopholes.

ThermoTweak

ThermoTweak is a cloud service that works with Nest to monitor your thermostat(s). It can automatically adjust Nest’s temperature swing to .05°F. This smaller differential allows your HVAC system to run more frequently, leading to more consistent, comfortable temperatures.

Set a Temperature Hold

Another way around the temperature swing is to set a temperature hold. A temperature hold forces Nest to keep a constant room temperature, which means the HVAC system will run more frequently.

Keeping a temperature hold on permanently is not advised. It’s an inefficient use of energy that can seriously drive up your heating and cooling bill. But in desperate times, a temperature hold is acceptable. Just don’t forget to turn it off.

More on Nest Temperature Readings

In addition to the automatic temperature swing Nest employs, there are other reasons for temperature discrepancies. Sometimes, the discrepancy is due to Nest, and other times, it’s because of the HVAC system.

Nest Uses Rounded Numbers

It’s not likely you’ll notice a difference in temperature by a tenth of a degree. However, if you’re glancing at your app, you may see a different temperature than what’s on the Nest display.

That’s because Nest uses rounded numbers. The temperature displayed on the Nest screen is rounded to the nearest 1°F. This practice simplifies things for the user. Do we really need to know our house is exactly 68.7°F?

However, the unrounded temperature determines when the system turns on. The multiple temperature sensors Nest uses take very precise readings to better inform your system. And these numbers can be viewed on your thermostat. Go to Settings > Technical Info > Sensors.

Temperature Change Takes Time

Remember that delay we talked about? With a delay from both Nest and the HVAC system, heating and cooling take a bit of time.

First, Nest has to recognize the room temperature has met its differential. Then, Nest has to tell your HVAC system to activate. Finally, your HVAC system turns on after its built-in delay times out.

Once your system is finally on, the heat or air has to disperse throughout the house. It should only take a few minutes for you to notice the temperature adjustment. But it also takes a few minutes for the ambient air around the thermostat to warm or cool. This prompts Nest to change the displayed temperature.

This is probably the most common reason you’ll notice a difference in the room temperature and the displayed temperature.

System Runs After Cycle

It makes sense why the room temperature might drop when the heat kicks off, but how might it continue to rise? And how about when we run the air? Why would the temperature continue to drop once the AC stops?

Some HVAC systems continue heating or cooling even after the cycle finishes. In the event there is heat or air left in the ducts, some systems run the fan to circulate what’s left. This means the room continues to receive heat or air for a short period of time, potentially changing the temperature.

With systems whose fans continue to run, you’ll notice temperatures in these homes tend to slightly exceed the temperature swing.

Related Questions

We’ve discussed much in the way of temperature swings and how Nest produces its readings. But perhaps you have more questions. Below are some things other users wondered about the functions of their Nests.

Why does Nest randomly change the temperature?

Part of the allure of Nest is its learning technology. Auto-Schedule is Nest’s learning program which is on by default. It chooses temperatures that have been set at least once before making adjustments as it learns your schedule.

Disable Auto-Schedule in app: Open the app and select your thermostat. Choose Settings > Auto-Schedule then switch it to Off.

Disable Auto-Schedule on thermostat: On the main menu, choose Settings > Auto-Schedule > Off.

Does Nest do half degrees?

Nest recognizes half degrees, but it doesn’t display them on the thermostat. The very precise temperature sensors activate the HVAC system when the room temperature drops a half degree below your optimum setting.

You can see the exact temperature readings by going to the Main Menu on your thermostat. Choose Settings > Technical Info > Sensors.

Why does Nest take so long to cool?

You may notice Nest display a message that reads “In 2+ hours.” Usually, that is Nest guessing how long it will take to cool your house. In reality, it probably won’t take that long. But it all goes back to the built-in delay of your HVAC system.

How do I know if my Nest is heating or cooling?

The color of the Nest display screen gives you a clue as to which mode you’re in. If Nest is trying to cool your home, the display screen will be blue. If Nest is trying to heat your home, the display screen will be orange.

Conclusion

Nest uses a temperature swing of +/-1°F from the temperature set point. The temperature swing is in place to prevent excessive wear and tear on your HVAC system.

For some users, the difference of 2 degrees is too drastic, and the wait to reach the setpoint is too long and uncomfortable. You can combat this by using the ThermoTweak cloud service which is compatible with Nest thermostats. It’s also advised to perform a temperature hold for a short period of time.

If these options don’t sound appealing, you may want to forget Nest and choose a thermostat with an adjustable temperature swing.

Brigid Levi

Brigid Levi is a wife, mother, and freelance writer who enjoys a good DIY project and creating beautiful spaces within her home. From cleaning and organization hacks to home decor ideas, she loves helping people in their quest to turn a house into a home. Her hobbies include pretending to be Joanna Gaines while updating her home with her husband and performing in local theater productions.

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