What thermostat differential means
The temperature differential is how far the room may drift from your setpoint before the thermostat starts heating or cooling again. ecobee calls it Heat and Cool Differential Temperature, and Google Nest calls it the maintenance band. A smaller differential keeps the room closer to the setpoint but starts the system more often.
What is a temperature differential?
A thermostat does not switch the heat on the instant the room dips a fraction of a degree below your setpoint. It waits until the temperature has moved by a set amount, then calls for heat or cooling. That amount is the temperature differential.
ecobee's definition of its "Heat Differential Temperature" is short: it sets the minimum temperature difference before heat is engaged. The "Cool Differential Temperature" does the same job for cooling. Google uses a different word for the same idea. Its help page says the delay is commonly called the maintenance band, differential, or temperature swing.
Without some differential, the system would start and stop every time the reading flickered. With a large one, you would notice the room getting warm or cool before anything happened. Every thermostat sits somewhere in between.
How does the differential play out in a real room?
Google gives a cooling example for Nest. Say your target is 70°F and the maintenance band is 1°F. The thermostat cools the house to 69°F, shuts off, and then lets the room warm up to 71°F before it starts cooling again. So a 1°F band works out to a 2°F range from the low point to the high point.
That range is what you feel between cycles. If you watch the display closely, you will see the reading move a degree or so above and below the target before the system responds. That is the thermostat working as designed. If the swing seems far larger than this, see our page on house temperature swings between cycles.
What is it called on each brand?
Only some brands expose the differential as its own setting. Others control it indirectly.
| Brand | Setting name | Where to find it | Published default(°F) |
|---|---|---|---|
| ecobee | "Heat Differential Temperature" and "Cool Differential Temperature" | On the thermostat only: Main Menu > General > Settings > Installation Settings > Thresholds. On Smart Thermostat Lite and Essential: Main Menu > Settings > Installation Settings > Thresholds | About 0.6 to 1 for heat (heating FAQ); cool not stated |
| Google Nest (Learning Thermostat, 4th gen) | "Heat temperature difference" and "Cool temperature difference" | Google Home app > Favorites or Devices > Climate > your thermostat > Settings > Equipment > Advanced configuration | Not stated; adjusted automatically |
| Honeywell Home (T4 Pro, T6 Pro) | No separate differential setting; the cycle rate controls it | Installer setup on the thermostat | Not stated |
| Emerson Sensi (1F87U-42WF) | Set by "Cycle Rate": Fast, Medium or Slow | Sensi app, System settings | Depends on cycle rate (next table) |
ecobee's heating FAQ prints its default oddly, but it works out to roughly 0.6 to 1°F. ecobee does not publish an allowed range on the thresholds page.
How does Sensi set the differential?
Sensi has no differential menu. Its "Cycle Rate" setting (Fast, Medium or Slow, found in the app under System settings) changes it for you. The spec sheet for the Sensi smart thermostat 1F87U-42WF lists the rated differential for each choice:
| System and stage | Fast(°F) | Medium(°F) | Slow(°F) |
|---|---|---|---|
| Conventional heat | 0.5 | 0.75 | 1.9 |
| Cooling | 0.9 | 1.2 | 1.7 |
| Heat pump, heating and cooling | 0.9 | 1.2 | 1.7 |
| Heat pump, auxiliary stage | 0.5 | 0.75 | 1.9 |
Sensi recommends Medium for most homes with ducted systems. On conventional heat, going from Fast to Slow widens the rated differential from 0.5°F to 1.9°F, so the room drifts further between runs.
How is the differential related to cycles per hour?
They are two ways of controlling the same behavior. A tight differential makes the thermostat react to small changes, and a high cycle rate does the same. Honeywell Home's T-series Pro thermostats use only the cycle rate. Honeywell says its thermostats are designed to hold temperature to within about 1°F either way, and our page on cycles per hour explains how that rate is set.
Neither setting overrides compressor protection. Even with a very small differential, an air conditioner or heat pump will not restart until its minimum off time has passed.
Is the Honeywell "Auto Changeover Differential" the same thing?
No. On the T6 Pro, installer option 303 is the "Auto Changeover Differential", with a range of 0 to 5°F and a factory value of 0°F. It belongs to the Auto mode, where the thermostat chooses between heating and cooling by itself. It does not set how far the room drifts during ordinary heating or cooling. Honeywell's guide also notes that this differential "is NOT deadband" and that Resideo fixes the deadband at 0°F with its own algorithm.
Does ecobee use a wider differential when you are away?
Yes. During Away activities, and in any Comfort Setting marked "Someone is usually Away", ecobee says the thermostat adds 1°F to the differential when it decides whether to call for heating or cooling. A room that drifts a little further while you are out is expected on an ecobee.
Should you change the differential?
Usually there is no need. Nest manages its band itself and says it balances your comfort against wear on the system. On an ecobee, the thresholds are set automatically unless "Configure Staging" is switched to "Manually", and ecobee suggests you contact its support first if you are not familiar with what your equipment can handle. On Honeywell Home and Sensi models, the differential follows the cycle rate chosen for your equipment type.
If one room never reaches the target at all, the differential is not the cause. That problem is covered in why a room never reaches the set temperature.
Frequently asked questions
- What is a good temperature differential setting?
- Most manufacturers do not publish a recommended number for you to type in. Google Nest adjusts its maintenance band automatically, and Sensi sets the differential through its cycle rate, recommending Medium for most ducted systems. ecobee says to contact its support before changing thresholds if you are unsure what your equipment can handle.
- Can I change the ecobee differential from the app?
- No. ecobee says threshold adjustments can only be made on the thermostat itself, not in the ecobee app. You also need to switch "Configure Staging" from "Automatically" to "Manually" before the individual thresholds can be edited.
- Why does the room get warmer than my setpoint before cooling starts?
- That gap is the differential at work. In Google's Nest example, with a 70°F target and a 1°F band, the thermostat cools to 69°F and then waits until the room reaches 71°F. On an ecobee, the gap grows by another 1°F during Away periods.
- Does my Honeywell thermostat have a differential setting?
- Not one you set as a number of degrees on the T-series Pro models. Honeywell controls how tightly the room is held through the cycle rate, and says its thermostats are designed to hold temperature to within about 1°F either way. The "Auto Changeover Differential" option is a different setting.