Picture of the Honeywell RTH9580WF thermostat, displaying its -Indoor Display Offsets- screen with a minus 1 degree temperature offset highlighted.

How to Calibrate Honeywell Thermostat Temperature RTH9580WF




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 tstat 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

How to calibrate Honeywell thermostat temperature RTH9580WF. Picture of the Honeywell RTH9580WF t-stat on same wall as a typical fridge freezer thermometer, used for temperature calibration.
How to calibrate Honeywell thermostat temperature RTH9580WF. Calibrating Honeywell RTH9580WF t-stat temperature, using a fridge freezer thermometer, with Both on same wall.

1. Get an Accurate Thermometer

For this demo, we used a fridge-freezer thermometer, which works pretty well.  But we suggest that you buy a glass thermometer that reads temps in the common household 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.

"How

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.

How to calibrate Honeywell thermostat temperature RTH9580WF. Picture of the Honeywell RTH9580WF t-stat, showing its -Main Menu- screen, with the -Preferences- button highlighted.
How to calibrate Honeywell thermostat temperature RTH9580WF. Honeywell RTH9580WF t-stat, showing its -Main Menu- screen, with the -Preferences- button highlighted.

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.

How to calibrate Honeywell thermostat temperature RTH9580WF. Picture of the Honeywell RTH9580WF t-stat, showing its -Preferences- screen, with the -Advanced Preferences- button highlighted.
How to calibrate Honeywell thermostat temperature RTH9580WF. Honeywell RTH9580WF t-stat, showing its -Preferences- screen, with the -Advanced Preferences- button highlighted.



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.

How to calibrate Honeywell thermostat temperature RTH9580WF. Picture of the Honeywell RTH9580WF thermostat, showing its -Advanced Preferences, Scheduling Options- screen.
How to calibrate Honeywell thermostat temperature RTH9580WF. Honeywell RTH9580WF thermostat, showing its -Advanced Preferences, Scheduling Options- screen.




4. Repeatedly Press Green  Next   Button Until you Reach the  Indoor Display Offsets   Settings Screen

See this screen shown next.

How to calibrate Honeywell thermostat temperature RTH9580WF. Picture of the Honeywell RTH9580WF thermostat, showing its -Indoor Display Offsets- screen, with the -Indoor Temperature Offset- buttons highlighted.
How to calibrate Honeywell thermostat temperature RTH9580WF. Honeywell RTH9580WF thermostat, showing its -Indoor Display Offsets- screen, with the -Indoor Temperature Offset- buttons highlighted.

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.

How to calibrate Honeywell thermostat temperature RTH9580WF. Picture of the Honeywell RTH9580WF thermostat, showing its -Indoor Display Offsets- screen with a minus 1 degree temperature offset highlighted.
How to calibrate Honeywell thermostat temperature RTH9580WF. Honeywell RTH9580WF thermostat, showing its -Indoor Display Offsets- screen with a minus 1 degree temperature offset highlighted.

6. Press the Red   Done   Button

Your t-stat then asks whether you wish to save your settings changes, as shown next.

How to calibrate Honeywell thermostat temperature RTH9580WF. Picture of the Honeywell RTH9580WF thermostat, showing its -Exit Advanced Preferences- screen, prompting for -Save Changes- confirmation.
How to calibrate Honeywell thermostat temperature RTH9580WF. Honeywell RTH9580WF thermostat, showing its -Exit Advanced Preferences- screen, prompting for -Save Changes- confirmation.

7. Press the Green   Yes   Button

The   Saving Changes   screen then briefly shows, as seen next.

How to calibrate Honeywell thermostat temperature RTH9580WF. Picture of the Honeywell RTH9580WF thermostat, showing its -Saving Changes- screen.
How to calibrate Honeywell thermostat temperature RTH9580WF. Honeywell RTH9580WF thermostat, showing its -Saving Changes- screen.

After the new temp offset setting saves, you see the next screen.

How to calibrate Honeywell thermostat temperature RTH9580WF. Picture of the Honeywell RTH9580WF thermostat, showing its -Preferences- screen, with the -Previous Menu- button highlighted.
How to calibrate Honeywell thermostat temperature RTH9580WF. Honeywell RTH9580WF thermostat, showing its -Preferences- screen, with the -Previous Menu- button highlighted.



8. Tap the  Previous Menu   Button

Then, doing so returns you to the  Main Menu  screen, as shown next.

How to calibrate Honeywell thermostat temperature RTH9580WF. Picture of the Honeywell RTH9580WF thermostat, showing its -Main Menu- screen, with the -Home- button highlighted.
How to calibrate Honeywell thermostat temperature RTH9580WF. Honeywell RTH9580WF thermostat, showing its -Main Menu- screen, with the -Home- button highlighted.

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 current 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 temperature.  This made up for that one degree.  So, the current temp stayed the same in this case.

How to calibrate Honeywell thermostat temperature RTH9580WF. Picture of the Honeywell RTH9580WF thermostat, showing its -Home- screen, after new temperature offset applied.
How to calibrate Honeywell thermostat temperature RTH9580WF. Honeywell RTH9580WF thermostat, showing its -Home- screen, after new temperature offset applied.

10. Done!

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.

Enjoy.



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References

Revision History

  • 2017-03-15: Originally published.