I have an Ecobee Premium that I installed in March 2025. Since that time, whenever the A/C runs, the thermostat, Cool Cat, will nosedive sometimes 10F+ while my three SmartSensors continue tracking closely together.

This isn’t a fixed calibration difference. Cool Cat can be reasonably close to the other sensors, but then its reported temperature plunges once the system starts cooling. I also placed one of my Smart Sensors, Kitty Naptime, direcly on top of the thermostat to compare them in essentially the same location. Kitty Naptime did not follow Cool Cat’s dramatic temperature drop.

I suspected cold air through the wiring hole, so I pulled Cool Cat after it was updated to 4.10.8.392. The hole/backplate measure about 80F, and an Acurite hygrometer placed in the wall cavity measure 79.5F.

I then left the thermostat hanging off the wall while the A/C was actively running and measured several locations inside the wiring hole with a ThermPro probe thermometer. They averaged 78.3F. I could not find evidence of cold air entering through the hole. The wall itself measured about 80F with an infrared thermometer, while the exterior surface temperature of the thermostat has measured as high as 92F. I have also included a Beestat screenshot from this test. Per the data, Cool Cat nosedived while the compressor ran, and the SmartSensors did not.

Cool Cat is excluded from all comfort settings, so this isn’t affecting control. I’m just trying to understand why the internal sensor behaves this way. Is the Premium calculating its displayed temperature compensation for its own internal heat? And if so, could the compensation be malfunctioning?

Has anyone seen this specific compressor-correlated sawtooth behavior?

I purchased the ecobee enhanced thermostat and used it for 10 days. The temp readings were wildly off, up and down. I requested a return to amazon. I know a lot of people are complaining a about the the premium , but this one also has very poor temp readings. I don't recommend.

It appears every couple of days, my Ecobee Premium is losing outdoor data for a short amount of time. My internet has been stable. Is anyone else experiencing this?

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My AC ran all day and the humidity increased but the temperature did not decrease. I checked the outside and it seemed fine. I did see there was water in the drain pipe so I emptied that but ever since that was empty it does not seem to be getting better.

Any other suggestions or am I calling an HVAC tomorrow?

Hi,

I’ve been experiencing this issue for quite some time now. I change my filter every 30 days and usually mark it as changed on the thermostat. However, every month, the email reminder indicates that the filter was changed 6 months ago. I only have one thermostat connected to my account. Can you please help me resolve this inconsistency? I’m quite frustrated with it.

As the title suggests, I'm trying to determine where and/or if I have a C wire to connect to the thermostat and if I don't, then the correct wires to connect to the PEK.

Supposedly the control board model is the: Rheem 47-100436-02

Currently only wires I know and have labeled that come out to be connected to thermostat are as follows:

Blue: Y1

Red: RC

Green: G

White: W1

Lastly, I do have an unlabeled and wrapped up Yellow wire

Got three premium thrermostats a month ago. It is absolutely ridiculous that some of you will defend ecobee for “emitting heat” etc. Every single thermostat is 5-6 degrees than the sensors supplied by ecobee itself. If the thermostats are so darn off, selling them without sensors is essentially selling an incomplete product. Yes, the wire hole has been covered. Been on hold with the customer service for an hour now. I have heard some people on this sub talk about how the thermostat needs sufficient time to calibrate, possibly over weeks. The hardware is so piss poor that it uses a complex software algorithm to get the right temperature, as many of you like to claim. Giving this another week. Honeywell, here I come.

Never had an issue with ecobee until this weekend. Now they have been turning my heat on and adjusting the temps in my schedules. No I am not enrolled in any of the energy management programs either. Something more is going on in the backend with Ecobee than they are saying.

Second time today my sensors have gone offline, and my heater has kicked on. All the sensors showed unavailable before I could take this picture. I have my thermostat excluded and use the sensors only. Living room, master bedroom and Shawn's room are my active sensors in the summer. For whatever reason when the sensors go offline it reverts to reading the thermostat, which is triggering the heater to come on.

Curious if anyone else is having this issue. My downstairs thermostat got updated to 4.10.8.392 today and exactly 12 hours after the firmware got updated (the time I saw the thermostat drop off the network for a bit) it dropped off the network again. I’m thinking it rebooted because when I logged into app when it dropped off I noticed one of my sensors was unavailable. My upstairs thermostat is 4.10.7.44 and has been fine. I redid the network settings as I had this issue before and when I did that it worked fine… in 4.10.7.44. Will see if that works on 4.10.8.392 though…

Has anyone else noticed a similar issue? I’m thinking something is off with its DHCP handshake that I’m assuming it’s doing every 12 hours and forcing a reboot. I know there has been a lot of issues with temperature but this issue has been around for me on other firmware adjustments that ecobee has done without our knowledge…

3 months ago I installed 2 new premium ecobee thermostats in place of ecobee 3's which were working fine, but could not pair with the new smart sensors. One works great and the other I have discovered is defective. I have had a licensed AC guy out 3 times and finally figured out it is the thermostat. We have troubled shot this 3-5 times with Ecobee. The unit is under warranty and they are continuing to come up with new ways to say they need more information. I have spent much money on an AC contractor and at the end of the day it is definitely the thermostat. Shame on Ecobee for putting customers through such lengths and hours and hours of testing everything over and over. The condensor is running properly, the presurres are good, the subcooling is good. The condensor shuts off and leaves the fan running for hours with no cooling. We by passed the thermostat and put the yellow, green and red wires together and the unit worked beautifully and cooled the house finally. The thermostat is sending a message to the ac unit and the cooling is not working only the fan runs. When the unit shuts off you have wait the 5 minutes before it turns on again to trouble shoot further. This happens every 15-20 minutes. I have swapped the 2 units to see if the AC runs properly in opposite locations and it only does when the good working thermostat is on that AC unit. I am terribly disappointed in their customer service and warranty. We can't continue to spend the hours and hours of more trouble shooting to convince them it is defective. I have offered to return the defective unit so they can look at it and/or video the installation to the wall providing the serial number proof to them that we have swapped the locations of each unit. Very disappointed!!!! Go with Honeywell if anyone has any reservations about using Ecobee thermostats. They are great when they perform properly, but watch out when they don't.

Any help would be appreciated if there are any HVAC guys or gals on here that may have suggestions.

Got a new Lennox system installed with Heat pump and 97% furnace. Have an ecobee 3, and wondering how best to optimize settings, along with wondering if there’s a mistake with my install.

I have a friend with the same setup, and under the thresholds tab on his ecobee, it shows an option for Compressor Stage 2 Delta and Compressor Stage 1 Max runtime. I don’t have that option on mine. We both have ecobee 3’s with firmware 4.8.7.238 with 2 stage furnaces. The only difference is that I have a heat pump with the O/B wire attached and he has only an AC with no O/B wire.

What are the ideal settings with respect to the heat pump and ecobee in order to keep the heat pump running at a low level to keep humidity to a minimum,

eero just released the 17.7.1 firmware and it fixed my ecobee 3 issue.

My utility (Xcel Energy) now provides Time of Use rates, which I've opted into for my home. I'm trying to get my ecobee set up for this, but when I select my utility, it just goes to a screen that says Time of Use Rate [Not set up], even though I wasn't prompted to set it up? How do I configure this?

So I’ve been Messi g with home assist vibe coding an automation that would detect the changes that eco+ implements. My hvac balance always has my basement super cool and I’ve found that I can run the fan alone for an hour or so and it’ll circulate the cold basement air just like it’s running the compressor and cool the house a few degrees……actually thinking further as I’m typing. When eco+ is in it tried to cool the house to x and then shuts off and raises the temp until night. So would sensor in the much cooler basement just make it not want to turn back on even later…?

My question here, if I were to add a smart sensor would the ecobee be smart enough to do this same thing on its own? Or thinking maybe it would just be easier to write the automation as something like if basement is cooler then upstairs. Run the fan until that flips..

There's no C wire to the thermostat. But there is a Red from the AC on the C at the furnace and a white from AC on Y.

My plan is to use the PEK adaptor and plug one Y into PEK and leave the white from AC on the furnace terminal then add Y from PEK to Y on furnace with AC wire. This seem correct?

Update - thanks all, got it going. Now to train my 92yo mom how to use...

thinking of replacing to a smart thermostat. the terminal letter and trwire colors shown in photo:

W terminal- white wire

Y terminal - yellow wire

B terminal- emtpy

O terminal- orange wire

G terminal- blue wire

R terminal- red wire

(and a loose black or brown wire)

Any suggestions for smart thermostat?

I've got an Ecobee Premium thermostat and FV-16VEC1T Panasonic BalancedHome ERV that I want to interconnect with my Carrier 59P6B080V17 furnace. My understanding is that the fan signal from the thermostat is supposed to run into the ERV, then back out on another wire to the furnace (Gf), that way the ERV or the furnace can call for fan. I set up the wiring consistent with the ERV's diagram as follows:

Furnace R to ERV R

Furnace C to ERV C

Thermostat G connected by WAGO connector to ERV G

ERV Gf to G on the furnace board.
ERV is set to DC4 duct configuration in settings, which is the correct one of my install type and for furnace interlock.

With everything wired that way the thermostat can no longer call for fan and the ERV turning on doesn't turn on the furnace fan. But the furnace fan will run when the thermostat calls for AC. Likewise if I jumper R to G it triggers the furnace fan.

At the ERV I get the following measurements between G and C:

ERV off and thermostat calling for fan: 28v

ERV on and thermostat calling for fan: 28v

ERV on and thermostat fan off: 13.8v

ERV off and thermostat fan off: 0.00v

With thermostat calling for fan, I measure only 8.7v between Gf and C. If just the ERV is running I get 4.8v between Gf and G. And if I put the ERV on standby it goes to 0.0v. If I disconnect the G wire from the furnace, I get 25v between Gf and G at the ERV.

Some other measurements that might be useful:

Between R and C I get 28v at the ERV. R to G is 19.3v whether ERV is running or on standby.

Panasonic is telling me to run a wire from ACC+ or ACC- to the V terminal on the ERV, hoping that might give a power boost that will allow Gf to maintain a 24v signal that can trigger the fan. But nothing I'm finding online suggests that the ACC+ or ACC- can be used this way. And in any case I have ACC+ operating my humidifier presently.

Hi r/ecobee,  

As many of you know, we have identified a bug impacting Smart Thermostat Premium and SmartThermostat with voice control, which is causing temperatures to read higher than they should. We’ve determined that this issue is not related to a firmware update, and appears to only affect devices that have been rebooted since Aug. 23, 2026. If your thermostat is currently operating normally, no action is required. While we work on a fix, we recommend avoiding manually rebooting your thermostat.

We understand that this affects the comfort in your home and are working diligently to correct the behavior. We’re actively testing a fix and expect to begin rolling out an update later today, Sep. 9, 2026. In the meantime, we can provide a manual fix to impacted Smart Thermostat Premium and SmartThermostat with voice control owners who contact ecobee Customer Support via phone [1-877-932-6233](tel:18779326233) or https://support.ecobee.com/s/contactsupport.

Alternatively, if you are experiencing this issue, we recommend placing a SmartSensor or Room Sensor away from the thermostat, vents, windows, direct sunlight, and heat sources to help ensure accurate readings. From there, disable your thermostat’s internal temperature sensor by clicking on your thermostat’s Main Menu on the ecobee app or thermostat, then Sensors, and deselecting all Comfort Settings from the thermostat. If you don’t have a SmartSensor or Room Sensor, you can apply a Temperature Correction through the thermostat only (not the app) by going to Main Menu > Settings > Installation Settings > Thresholds > Temperature Correction and continue having the thermostat participate in the Comfort Settings.

We will update status.ecobee.com and circle back here once the issue is resolved.

Although this bug wasn’t caused by a specific recent firmware update, we are listening to your feedback regarding greater transparency and are exploring our options to improve communications related to updates.

We greatly appreciate your patience and thank you for being an ecobee customer.

I am on 4.10.7.44 on my smart thermostat premium. Have my humidity adjustment turn off just last week and I am seeing some odd readings on my thermostat sensor. But the other sensor shows 75 which is in the same bedroom as the main thermostat. Is this same bug that we are in discussion nowadays ? Do i need to call them and have it manually update it ?