In this post, we show how to calibrate Honeywell thermostat temperature RTH9580WF. Now why would you wish to calibrate the temp reading on a thermostat (t-stat)? Well, perhaps your Honeywell t-stat reads warmer or cooler than the room feels. So you’d like to bring the t-stat temp reading more inline with how it really is.
Or, maybe you put your t-stat on an extra warm wall in your home. If so, the rest of the house may feel too cold in winter, and too warm in summer. Or vice versa. That is, if you place the t-stat on a cool wall, then the reverse may happen. The rest of the home might feel too cold in the summer, and too warm in winter.
Now the t-stat reading may simply be wrong. Or the reading is right. But the t-stat sits in an extra warm or cool place in the home. To solve these problems, calibration of the t-stat will likely help.
Calibrating a t-stat is a simple process really. So long as the t-stat you have has a temp offset setting, setting it the right way is easy. Honeywell does in fact, have this offset setting in its 9000 series RTH9580WF internet controlled t-stat. This is the t-stat we use in our home. So, we’ll discuss next, how to set this offset for better comfort control from this t-stat.
Note that this post applies to the other series 9000 Honeywell t-stats as well.
How to Calibrate Honeywell Thermostat Temperature RTH9580WF
The calibration process has two main steps. First, you figure out how far off the sensed t-stat temp is from real room temperature. Then, you set the t-stat temp offset parameter to account for that. Simple, right? Right!
Find Honeywell Thermostat Temperature Offset
1. Get an Accurate Thermometer
For this demo, we used a fridge-freezer thermometer as a reference, which works pretty well. But for best results, buy a glass thermometer that reads temps in the temp range from 50 to 90 degrees. Not only does this thermometer read more accurately, its scale is often larger. So, it’s easier to see.
2. Place the Thermometer Near the Thermostat
Put it as close as you can. We hung our thermometer on the same wall as the t-stat. See the picture above.
3. Allow Temperature Readings to Stabilize
Let the thermometer hang for twenty minutes to a half hour. This allows it to accurately read room temp.
4. Read the Thermostat and Thermometer Temperatures
In our case, the thermometer read the room at 76 degrees F. But the t-stat read it at 77 degrees F.
5. Compute the Temperature Offset
Now assume that the thermometer reads the more right of the two. Then, the room temp reads 1 degree less on the thermometer than what the t-stat reads. We need this figure in the next task.
Calibrating Honeywell Thermostat Temperature Offset
Many Honeywell t-stats allow setting the -1 degree temp offset we found above with the thermometer. Here, we show how to do it on our 9000 series RTH9580WF Wi-Fi thermostat. You start at the Home screen, as shown next.
1. Tap the MENU button on the Honeywell Thermostat Home Screen
This brings up the t-stat’s main menu, as shown next.
We then scrolled down using the arrow buttons, to bring the Preferences item into view.
2. Tap the Preferences Button
Find this button pointed at by the pink arrow in the last picture.
The Preferences screen then shows, as seen next. We then scrolled down using the arrow buttons, to bring the Advanced Preferences item into view.
3. Tap the Advanced Preferences Button
This shows the first in a series of advanced settings screens then; the Scheduling Options screen, as shown next.
4. Repeatedly Press Green Next Button Until you Reach the Indoor Display Offsets Settings Screen
See this screen shown next.
5. Adjust Indoor Temperature Offset
Use the UP and DOWN arrow buttons to set the indoor temp offset. So we circled these in pink, in the last picture.
Recall that we found -1 degree F for our temp offset. Thus we tapped the DOWN arrow once to enter -1 degree, as shown next.
6. Press the Red Done Button
Your t-stat then asks whether you wish to save your settings changes, as shown next.
7. Press the Green Yes Button
The Saving Changes screen then briefly shows, as seen next.
After the new temp offset setting saves, you see the next screen.
8. Tap the Previous Menu Button
Then, doing so returns you to the Main Menu screen, as shown next.
9. Tap the Home Button
This completes then, the temp offset setting routine. The Home button returns you to the t-stat’s Home screen, as shown next. Note that this screen appears as it did before we changed the temp offset. E.g. The temp still reads 76, and so does the set temperature. But our place now feels a little warmer (one degree warmer, in fact). Now had we made a bigger change, such as -4 degrees, then the current t-stat temp would read lower.
But since we changed ours just -1 degree, the furnace had enough time to raise the room temp. This made up for that one degree. So, the current temp stayed the same in this case.
Finally, your HVAC system will now, for negative temp offsets, keep your place a little warmer. Further, for positive temp offsets, your home wil stay a bit cooler.
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- 2019-04-11: Removed ad code and shortened post URL. Added tags.
- 2019-01-27: Adjusted key phrase targeting, and added some tags.
- 2017-03-15: Originally published.