ecobee3 Thermostat Displaying Wrong Temperature? Here is Why!

Ironically yesterday my wife and a reader had the same question on the exact same day prompting this really quick post about your ecobee3 and the temperature that it displays.

‘the ecobee is displaying the wrong room temperature no way is it 69 in here right now’

Of course my wife is NEVER wrong on anything, period and in this case she was also not wrong.

Yes the thermostat said 69 and it was not 69 in the room where my thermostat was installed it was actually a ridiculously warm 78. Is my ecobee3 broken? Is the ecobee3 flawed and reporting the wrong temperature? Is the ecobee3 installed in a really bad location?

No to all three.

The ecobee3 is doing exactly what it was designed to do because it has a remote temperature sensor attached to it installed in our bedroom. The bedroom sensor is also set as the control sensor so when I look at my thermostat it is actually displaying my bedroom temperature not the temperature in the rest of my house.

When I walk up to my thermostat it says 69 but it is in fact 78 and that makes perfectly good sense since in my settings I told the ecobee3 to use the bedroom temperature to control the ecobee. So my thermostat is overheating the home to try to heat a badly ducted bedroom.

Side Note: Clearly I do not want the rest of my house being 78 just so my bedroom can be 78 because that is just ridiculously warm. Remember that the ecobee sensors do not replace proper zoning nor does it correct poor furnace duct work which is my issue ( Read more on this topic : ecobee 3 Remote Sensor Fail )

The other option for the ecobee was to set it so that instead of it looking only at my Bedroom it will do the average between the bedroom and my main floor. That should make our bedroom more comfortable and also stop the crazy overheating that is happening right now.

Now my thermostat is typically reading 71 degrees. My upstairs bedroom is 67-69 degrees and my main floor is around 73 degrees on average. So again my thermostat is NOT showing the temperature at the stat it is showing the average temperature between the bedroom and the mainfloor where my thermostat is installed.

These settings are much more ideal but at times we are still a bit warmer then we would like to be so there is definitely more I can do. Normally the human body can not notice a difference of 2 degrees so ideally I want to try to get my ecobee3 sensors to read within 2 degrees of each other which is tricky since the sensors as cool as they are, do not have magic beans in them.  IE it wont replace zoning and can not overcome my horrible duct work which I consistently whine about.

Another thing I could look at is adding more sensors for more temperature averaging. One ecobee3 remote temperature sensor per floor to give a true operative mean temperature across all three floors. The ecobee3 wont try to heat to the worst condition it will simply average all three floors which would certainly work better then any other thermostat I have used.

Moral is simple. ecobee3 = best smart thermostat on the market. Use it right, know how it works and you will likely end up alot more comfortable then you were before.

Update: January 8ths 2013: As of a few days of running my thermostat using temperature averaging my home as a whole is much more comfortable. The mainfloor is 4 to 5 degrees warmer because of it but from a comfort standpoint its much better. 

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11 Comments

  1. Have you verified that the main unit is reading an accurate temperature? I’m having an issue where the main unit is throwing a higher reading when cooling due to the unit overheating from the current draw…i’m curious if you put one of the remote sensors close to the main unit if they both read the same…

    1. My unit is reading an accurate temperature. If it wasnt the really simple fix is to use the built in temperature adjustment to get it to where it should be.

      If you are going to do this make sure you are using a GOOD quality temperature device not a low cost remote sensor and certainly not a fridge thermometer as it wont be nearly as accurate as the ecobee3 sensor.

      Also as silly as it may seem its VERY important that the opening behind the stat is also filled in with insulation to prevent negative pressure pulling heat up onto the thermostat.

      Tks for the comment.

    2. I put my remote sensor next to the unit and it’s reading 2 degrees higher and I’m not sure why. I had the sensor placed downstairs and it was reading 5 degrees higher than the main stat, and I thought this was a little high but not really sure if it’s right or not. With the Follow Me mode enabled and the stat set to use the downstairs sensor during the day, I was wondering why my AC was running non stop. It just couldn’t pump enough cool air to the downstairs to ever get it down those 5 degrees. I’ve now turned off this feature and using the average. Thanks to the original poster of this article!

      1. The ecobee remote sensors will never replace bad ductwork but if you have reasonable ductwork the ecobee remote sensors are superstars at improving overall comfort in your home.

        Have you considered snagging a few extra sensors?

        You could put one in the basement, one upstairs and one on the mainfloor and they would work together to produce a better overall average temperature.

        In my own home the temperature difference between floors was obscene so in the winter time some of my rooms were literally ovens while other floors were ‘comfy’.

        By using averaging with more sensors I would suggest the overall effect would have been better.

      2. @MacGruber I had actually read your other article on sensor averaging just after posting (great article BTW really helped me understand what was going on). The issue I have is similar to yours and that is I simply don’t have good ductwork going to the area where I want to put the sensor. I could put more sensors around the house and I may purchase a couple more to test this out. However, the new issue I’m having is that the main stat temperature is reading 2 degrees higher than my old stat (I also tested the Nest and this matched my old stat) and I’m not sure why the E3 is higher. Note this is without the remote sensor activated. So for now I’ve got a -2 degree offset in place on the main stat and this seems to create a higher average when coupled with the remote sensor which is naturally reading higher because of the bad duct work. The result of course is longer AC run times.

        Right now I’m just trying to use the remote sensor for its motion capabilities so I can get the away mode working more effectively. That’s a whole other problem entirely!

  2. My new ecobee3 is not only reading wrong temp. It doesn’t drop as the room cools but when heat pump kicks on it drops 3 or 4 degrees to where it probably should be. Even when heating it doesn’t rise as quick as it should.

    1. Hey bob thanks for commenting a couple of quick things. First off make sure you are not checking the temperature with a $5 meat thermometer. The ecobee is a highly calibrated device and comparing temperatures across a low grade and a high end product is not going to give good results.

      That said the other thing you should check is that you do not have a GAP behind your thermostat. When your system starts up that temperature drop could be negative pressure pulling cold air across the thermostat. You may think ‘impossible’ but as somebody who works in the industry I also said ‘impossible’ and found I was 100% wrong and that what I described was the problem.

      Obviously BE CAREFUL I offer no warranty or guarantee’s of any kind and you can damage your furnace shorting wires while attemping to fill said gap.

  3. The black square is the thermostat which contains a sensor. The software lets you include – or not – that sensor in the average temperature calculation. The white sensor can be placed in any location (there is a distance limit from the black square) and the software can use that sensor (or not) in the calculation. You may use addition sensors, but obviously at least one sensor must contribute to the calculation.
    Hope that helps

  4. I’d just like to say that it’s not ironic that your wife and a reader had the same question on the same day. It is coincidental.

    By the way, while I have ecobee at work, not at home – the bedroom sensor would make more sense for us since cool temp at night while sleeping is more important than temps during the day. But ideally we could switch which was the control during certain time periods daily.

  5. I wish there was a way to override this functionality. I routinely ask Alexa what the temp is downstairs. when only the remote sensor is functioning upstairs, the ecobee does not report the correct temp at the thermostat. The web when you look at sensors does correctly report. Kinda a pain when you want to make sure downstairs does not get too cold in the winter.

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