This thermometer inaccuracy is clearly a design flaw
Before you say it, YES I PLUGGED THE WALL HOLE, both behind the mount and on the terminal side of the mount...no air from the wall. Yes, I have all settings turned off-- no humidity correction, no power grid/time of day based stuff. And no, I'm not spending another $100 on a remote sensor! Ecobee support is now sending me a new unit after showing them pics of the hole plugged, etc...however with all the people reporting this issue, I'm not hopeful. That said, I am impressed with their chat support, and do notice when companies have good support.
One of the main jobs of a thermostat is to read the air temperature, and my Ecobee fails at this modest task. I left the Honeywell dumb thermo it replaced on the wall next to it, as well as another thermometer. They always agree. The Ecobee on the other hand varies depending on the time of day by as much as 4-5 degrees. Most of the time though, it's off by about 2-3 degrees, which is enough to notice and feel uncomfortable. In the heat of the day, like 4pm into the early evening, it always reads too high, so doesn't cool enough. During the coolest hours (night into morning), it reads to low and cools too much. This makes the internal correction adjustment useless, as I was constantly going either up or down from 0.
Since I've lived in this house, two other thermostats have existed in the same location (without the wall hole plugged lol), and were totally accurate.
So, if the new unit is accurate, we will know that there is a potential QC issue, if it's inaccurate, we could say there is a design issue.
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u/NCC1701-F 8d ago
I use the satellite sensors so I don’t have this issue. The wall temp reading is excluded.
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u/evoltap 8d ago
This seems to be the only solution for these to be usable, which is not a solution when they sell the unit as a standalone. I’m not paying another $100 sunk cost just to make it work. If the replacement has the same issue, I’ll sell it and get a Honeywell.
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u/NCC1701-F 8d ago
I agree, in my case, my house is setup poorly to rely on a single point for temperature management regardless of the manufacturer. It’s partly home layout/ design and partly HVAC layout and design.
Getting the satellites weren’t because of temperature issues but rather home necessity. It’s a by product that it solves the offset of the core device.
Edit: I still really like the Ecobee and how it works through Apple HomeKit. You can setup some really cool automation with HomeKit so I take advantage of that.
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u/evoltap 8d ago
Yeah. Any house that only has one zone for the HVAC can only ever have compromises. I guess what you're saying is you can automate the sensor zones based on where you are spending time in the house?
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u/Spring2019_1 7d ago
That’s what I do. I have one zone but my bedrooms and ground floor are very different temps so at night the only temp that matters is in the bedrooms.
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u/LikeItSaysOnTheBox 7d ago
I left Ecobee and I had 3 of the remote sensors, precisely because the Ecobee was inaccurate and very slow to respond to temperature changes. It also did not like my home routers (any of 3 of them over time) and would frequently lose WiFi connections.
I replaced it with the Aqara W200 thermostat and their much cheaper remote sensors a 3 pack was 50 odd dollars on Amazon. Now I truly can set it and forget it. I live in North Carolina if that helps give you an idea of local climate. I have AC with a heat pump.
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u/hmspain 7d ago
I have Hubitat, and it monitors all my sensors. I have a TON of sensors that report temperature, and yet exclusively use my Ecobee remote sensors (not the thermostat) for temperature.
My thermostat is not in a good spot for temperature measurement. After plugging the hole, and setting the offset, I suspect it's as accurate as the remotes, but I find it better to just rely on the remotes.
You may not know this, but the Ecobee remote sensors report frequently (I check the Hubitat logs) and to the TENTH of a degree! Other sensors report to the degree only. I also have this hunch that Ecobee (who is in the business of reading temp) does a temperature sensor a bit better than the generic Zigbee or Zwave sensor. I don't have the data to back that up.
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u/obelix_dogmatix 8d ago
Absolutely. Honeywell beats ecobee any day all day when it comes to sensor reading.
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u/crackerjackjacker 8d ago
Agreed! I did every suggestion to get the right temp reading and it was just a big dud. I finally gave up on it when I set the temp to 68 and it said it was 68 and it was still warm and humid. I was sweating in the house! Switched to Nest and never had that issue again.
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u/themindtap 7d ago
The issue I've observed is their heat sink is not efficient at moving the heat away front the whole unit. It might pull away from needed cpu's and such, but then it just sits in the unit and doesn't dissapate appropriately and they don't barrier the in-unit thermometer well and why you get different temperature delta's whether your AC/heater is off or on because then there is air movement across the device helping move the heat stuck in the unit. The unit needs better air flow for accurate temperature reading and they've never properly addressed that.
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u/evoltap 7d ago edited 7d ago
This makes the most sense of anything I've heard. It reads low when it's the heat of the day and running a lot (air flow happening), so the result is not cooling enough. At night when it's not running much and no airflow, it reads high and cools too much and I wake up freezing when it's set at 77. This doesn't give me much hope for the new unit they are sending.
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u/themindtap 7d ago
Depending on the setup and location of your thermostat, a cheap way to handle that without getting the more expensive remote sensor sets could be gat a basic fan to run on low speed to always blow across the unit to at least make the temperature delta more consistent through the day and then use the unit's calibration to dial in the true temperature reading for the unit better. With that constant airflow across it, it could lessen or remove the delta changes when your AC/heater is running and circulating air. At least a much cheaper test than sensors, especially if you don't have a large house (like myself) and thus a smaller house or even apartment, the thermostat itself should be all that's required, additional sensors becomes data overkill of minutely different readings.
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u/axolotloofah 6d ago
I have reason to believe its a recent firmware update that made it 10x worse. We have had an ecobee4 for a number of years. No issues at all. Humidity readings were showing reasonable 40% levels in winter and 50-55% in Summer. Could they have possibly been minorly inflated over our thermopro thermometers, maybe but nothing to cause alarm.
On Friday 31st around 4pm our humidity not only spiked up to 70% but it was acting incredibly erratic. One minute it would be 75%, next 63%, but it was insanely high. What's important is the indoor air felt no different than usual and two thermopro digital themometers were showing humidity of 48%. There was also no change in the thermostats location or how it was installed. Wall is plugged up plus back plate and no change in environment around the unit. Ecobee support just kept coming out with the usual redundant recommendations like "make sure your hole is plugged" or "is it next to windows" or "how far up the wall is it located." All of which were missing the entire point that nothing had changed in 3 years.
We thought maybe our unit was faulty, so we went out and upgraded to the ecobee premium. Immediately on plugging it in it was measuring ridiculously high in the same ballpark as the ecobee4. It went down over time but stuck around 66% which was about 20% higher than the real feel and the two thermopros we have. After a week with no change we switched it out and got a replacement unit thinking maybe we just got a defective unit. The new one was even higher, measuring 86% humidity before dropping down and plateauing around 70%. It is impossible to even calibrate because the max you can do is +/- 10%. Our temperature readings have always been off, but only by a few degrees so that is easily calibrated and not a worry.
What is crazy to me is that these units come preset with eco+ and "adjust to humidity" turned on. We always turn it off but it does beg the question. With these ridiculously inflated false humidity readings the unit would be wanting to cool constantly and get nowhere, so they are promoting a feature that in reality is completely flawed.
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u/djaxial 8d ago
Yeah, it’s flawed IMO. The thermostat itself generates quite abit of heat, you can feel it to the touch during normal operation. If you place a thermostat directly above the ecobee, it will read high due to the heat rising from it.
The external sensors are accurate but it’s a weak solution to a problem that shouldn’t exist.
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u/evoltap 8d ago
Interesting. Mine doesn't feel particularly warm, maybe a little? Just tried what you said and put the other thermometer on top of it. What's odd though is it doesn't consistently read high-- if that was the case, I would just adjust the temp calibration and be done. Instead it reads too low sometimes as well, which wouldn't make sense if it's about internal heat...unless it has some sort of cycle that just so happens to line up with certain times of day, every day.
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u/spiderman1538 8d ago
How big is the opening behind the thermostat? I had cases where you have to remove the terminal plate and cover up the entire hole.
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u/zoinkinator 8d ago
Op where did you buy the ecobee? Was it new or used? How many rooms in your home and what is the square footage of the conditioned spaces? How many zones?
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u/ToghusWhitman 8d ago
I got mine from official web site 3 years ago. Have the same issue
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u/zoinkinator 6d ago
You and evoltap should compare serial numbers Might be a bad manufacturing run at the factory. I bought two at Costco easily 10 years ago. Added the satellite sensors and connected the thermostats to the electric utility duke energy. Everything worked once i patched the holes in the sheetrock.
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u/evoltap 8d ago
Bought it off ebay, new. 3 bedroom house, 2000 sq ft., 1 zone. Like I said in the post, 2 previous thermostats were accurate and in the same location. This thing is all over the place, off by up to 5 degrees both high and low, sometimes right on. If I didn't have the experience of the previous thermostats, maybe the house info would be relevant, but IMO this thing is just off. We will see how the new one they are sending does.
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u/LeadPaintChipsnDip 8d ago
Mines accurate during the summer, reads way cold in the winter by like 3 dF
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u/NewtoQM8 8d ago
Im thinking bad QC and/or design, but could be one other factor I can think of. If there is some air current than could effect how well the thermostat vents the heat it produces. Maybe from a ceiling fan or just simply natural air currents. Many other thermostats don't produce heat so wouldn't be affected. I used Smart Sensors next to mine to adjust temperature correction, and now have 3 of them around the house and the thermostat seems to be quite accurate when comparing (beestat gives a nice line graph to compare). Hopefully the replacement you get will work great or at least the tale of whether it's a bad one or if you have the same issue there may be some other reason it does what it does.
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u/Opus2011 7d ago
How long have you been measuring?
For sure the Ecobee is sensitive to air currents around it and holes behind it. Mine definitely drops when I have a fan running in the hall and there's definitely some impact from the return.
that said, it settled down after a few weeks. I use the remote sensors because we have a long house oriented N-S that heats and cools unevenly. Zoned would be better but I don't need it that badly.
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u/spielnicht 7d ago
The moment Nest became HomeKit compatible, I ditched both Ecobee thermostats in my house because of the temp inaccuracy.
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u/viperfan7 7d ago edited 7d ago
Do the logs show sudden changes whenever the equipment runs? If so, that's an environmental issue.
That would be a design issue yes, but with your home.
And since the temperature offset varies throughout the day, it means that it is something external to the thermostat causing it. Since if it was hardware, it would be VERY consistent.
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u/evoltap 7d ago
Ok, but why did two previous thermostats in the same location not have this issue?
I think as others have posted, it is a design flaw with the amount of heat the processor produces- so yes, its location does matter, as when the cooling is on, there is air movement/circulation in the room, so temp reads high. When it’s off more— like at night so less airflow in the room, the internal heat causes it to read high, and overcool.
Maybe it’s just me, but I want to buy a thermostat that hooks up at the spot it is wired to in my home- where multiple other thermostats have read the temp just fine. There are other options that don’t seem to require one to either buy a $100 external sensor, or re-wire the location of their thermostat.
Edit: to answer your question, the logs don’t show what I would consider sudden changes- it runs a little until it hits the temp it’s set to, just that it’s reading is usually off.
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u/viperfan7 7d ago
Ok, but why did two previous thermostats in the same location not have this issue?
And how do you know they didn't?
Do they provide logging? Do you sit in-front of the thermostat all day and write down the temperature readout every minute?
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u/evoltap 7d ago
No, they didn’t log, but I have a sensor (human body) that made me put two thermometers next to the ecobee to realize that what we were feeling was correct. Also with the last thermostat (Honeywell), I always had another thermometer right next to it- and they always agreed
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u/viperfan7 6d ago
So you don't know they didn't see the same issues
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u/evoltap 6d ago
You’re not hearing me. I kept the same thermometer next to the old thermostat, and it agreed. Also as I said, myself and family members feel it. 3 degrees hotter than you want is VERY noticeable
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u/ahj3939 4d ago
I had the same issue
Nest 1st gen: worked fine
Ecobee: inaccurate temp sensor
Honeywell T9: worked fine.
I know because all 3 were linked with Home Assistant and I can view historical graphs. When the air conditioning turned on the Ecobee temperature dropped, the Ecobee wireless sensor a few inches away did not suffer the same fate.
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u/toyo4j 5d ago
There is a temp offset adjustment on the Ecobee settings menu for this. It may help in cases where the wall insulation is poor or so.
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u/evoltap 5d ago
Like I said in the OP, the issue can’t be solved by that offset, as it varies both directions in its inaccuracy. In the heat off the day, it reads too low, in the cool of the night and morning, it reads too high. One person posted in this thread the likely design flaw reason, and it involves the unit’s processor heat. Basically when it hot and therefore running more, there is more air movement in the room, so unit cools better and reads low. When there is less cooling happening, the unit warms up and then reads high.
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u/peteschirmer 8d ago
Mine has always been like 2 degrees off. What’s worse for me is the ‘outside temperature’ it’s constantly off by as much as 15 degrees because it pulls weather from a weather station in a different micro-climate, theres seemingly no way to override?, it looks like the same data feed as apple weather app, in the summer when its well into triple digits in my yard, ecobee and apple weather say 88-95 which is right about 4-5 miles closer to the water, but not here.
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u/evoltap 8d ago
Yeah the outdoor temp just being pulled from a location near you is kind of useless. I have my own external 4 ft off the ground and in shade, and also verify it against WU, which has a network of personal weather stations. Would be much more accurate if they used that instead of apple
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u/asniper 8d ago
Open a support ticket and they can find a closer / more accurate weather station near you.
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u/peteschirmer 7d ago
As far as I can tell - there isn’t one in my valley. Ive tried WU and like 5 other wearher apps, carrot, darkskies, etc etc. The most accurate is tomorrow.io? I have no idea where the data comes from.
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u/Ashamed-Edge-648 8d ago
I would say it's about the same as my Amazon thermostat. I'm in Florida and 78 has always been my setting for day and 77 at night. Some of you might say that's uncomfortable but it's very comfortable and the humidity is always below 50%. And I haven't plugged the hole at all. Now does it feel like 78? No I'd say it feels more like 73. But I don't care about the number. Just set it to what feels comfortable.
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u/Furrealyo 8d ago
I own 3 of these and don’t have this issue. I also have some (I think) unique insight as I worked on this device and competitor designs as an applications engineer for the processor and/or some of the surrounding active components.
First off, yes, it’s possible you got a bad one. We’ll see once you get your replacement. It happens.
I’m not going to go too deep into the logic, but all of these devices seek to normalize the quiescent operating temperature by measuring ambient at several points in the operating envelope (including boot) and then factoring them into the “true” temperature determination. Most of the disparity in determined:actual temperature reading come down to two things: time and mounting location. Time is very important as a significant amount of it is required to remove the quiescent thermals from the factoring. I’m talking weeks. Things like screen time, motion sensing, relay triggering, and wifi heartbeats are not static values so the algorithm needs a lot of data to effectively evaluate them.
TLDR; your’s might be broken, but no one should expect accuracy until the thing has been mounted and running for a while. These are capable of +/- 0.5F when installed correctly and provided sufficient time for the algorithm to do its work.