Nest Learning Thermostat isn't accurately registering temperature

[Chasfliesu]

Very frustrated...my nest target temp is 20.5 and it's showing the ambient temperature to be 21...two other thermometers sitting less that two feet from the Nest are registering 19.5 and have been now for over half an hour and Nest has not turned the boiler on.  The Nest is and the other two thermometers are effectively in the same place and Nest is not being affected by any other potential source of warmth that the other two aren't.  How can I calibrate it?  

[AnaM]

Hey @Chasfliesu,

I'm sorry to hear about this issue. The temperature difference you mention is at the limit of the expected difference in the temperature readout. The Nest Learning Thermostat (NLT) 3rd Gen and the Nest Temperature Sensor can differ in temperature readouts as much as 2 degrees Fahrenheit (one degree Celsius). You should only consider the temperature difference as unexpected behavior if the difference is 3 degrees Fahrenheit (1.5 degree Celsius) or more. However, we can try a few things and see if we can improve the readings.

First of all, please give me a picture of the power readings found on the thermostat in Settings> Tech Info> Power. 

Restart your thermostat by going into Settings> Reset> Restart. Monitor it afterwards and check if it reads a more accurate temperature.

[DragosC]

Hi there. I'm just following up on our last message. Do you still need our help? Keep us posted. 
 

[Chasfliesu]

I am still puzzled by what seems like 'mysterious' operation of the Nest thermostat...I sent the photos that Ana had requested from my phone but never got a reply from her.  Yesterday we were out most of the afternoon, the thermostat was set to 17 degrees from 12:00, we arrived home just before 17:00 and the heating was on, even though it was still set to 17 degrees and not supposed to increase to 20.5 degrees until 18:30.  I'm worried this Nest is going to have us using MORE energy than we used to when we had a simple Salus programmable thermostat.  As I said in my reply to Ana, I've switched off the Auto-Schedule function and it still is behaving as I've programmed it.  

[DragosC]

Thank you. Could you tell me please if you have any case number in our system? Did you send those pictures to her on the email? 

[DragosC]

Hi there. I'm just following up on our last message. Do you still need our help? Keep us posted. 
 

[Chasfliesu]

Hi Dragos, thanks and sorry for the slow response...just been a very busy couple of days and I've been away from home a lot of the time.  
Yes, the Nest Learning thermostat is still sort of doing it's own thing...it still seems to be coming on whenever it feels like it and it also doesn't seem to 'sense' when we're away.  On Saturday, we returned a little before 5 PM and the heating was on when we arrived home and it wasn't set to come back on until 6:30 PM.  Any suggestions you can make would be greatly appreciated.  there just doesn't seem to be any logic to it.  The only thing that seems to be working correctly is it does switch off the central heating when the it's supposed to go to 17 degrees...it's just when it decides to switch itself on that is a worry.  I'm afraid using it is going to wind up using more energy than with the old manual Salus programmable one we had before.  

[george_t]

Hi @Chasfliesu, thanks for the details. Can you please tell me if my colleague has created a case for you? Where did you send the photo with the power readings?

[Chasfliesu]

Hi George...so far no one has created a case for me...I just replied to Ana's first message, but had to reply from my phone because that's were the photos were and it was easier to attach them from there...but then I dropped them onto my desktop and tried to send them from within this chat to Ana, but it gave me some error message.  

[george_t]

Got it. Can I use the email address on your page to create a case for you?

[Chasfliesu]

Yes please!  

[george_t]

Thank you. I just sent you an email. Please check to see if you receive it. 

[Chasfliesu]

I did and just completed the form.  Cheers!

[DragosC]

Thank you. Could you tell us please when did the situation start occurring first and when was the thermostat installed? 
 

[Chasfliesu]

Hi Dragos,  The thermostat was fitted on the 21st of March and immediately I noticed that it was registering a higher temperature than the old Salus thermostat which is directly above it and a portable weather station that I placed right next to it...it was recording 1 to 1.5 degrees lower than the other two.  
From the beginning, it was also turning on the heating anywhere from 30 minutes to an hour or more before the time I had set for it to come on.  The other night, the weather outside had been warm and sunny and about 8:30 PM I suddenly was aware of feeling VERY warm...discovered the heating was on, the temperature on the Salus and weather station was 23 degrees and on the Nest it was set to 20.5.  I'm ready to revert back to the old Salus, but I'd have pay someone to come to fit it!    As I have said, the Nest switches the heating off on time, but it seems to have a mind of it's own when it comes to switching it on and I'm worried that it will increase my energy consumption as a result!

[DragosC]

Understood. Thanks for the explanation and the details. Could you provide me please with a picture with them one next to another? 

[CristianC]

Hi there. Just checking in. How's it going with your thermostat?

[Chasfliesu]

Hi Christian, It's pretty much the same...but harder to tell right now because temperatures have generally been warmer, so the heating hasn't been activated very often in the last two weeks or so.  What is consistent is that the temperature recorded on the Nest is inconsistent...compared to the two other thermostats/thermometers that are effectively sitting next to the Nest.  Sometimes they register the same temperature and sometimes not...this morning, the other two were showing 20 C when I got home from the gym and the Nest was showing 20.5...sometimes they show temperatures that are warmer than the temperature shown on the Nest...does this thing calibrate itself or is it random?  Thanks for following up, but I'm still not confident that the Nest is reliably going to regulate the temperature in my flat in such a manner as to reduce my energy consumption...but I'll patiently wait to see how it goes for now.  

[CristianC]

Hey @Chasfliesu, Each thermostat calculates the temperature differently so a difference of 1 - 2 C is expected. If you see higher discrepancies in the temperature readings, please share a photo. The thermostat does recalibrate the sensors after a restart. You can do it from Settings > Reset > Restart. I see that the main issue with your thermostat is that it turns your heating on randomly. Can you check if you have True Radiant enabled? ( Settings > Nest Sense > True Radiant ). This is a pre-heating feature that turns your heating on earlier than scheduled and it might seem that it turns on randomly. 

[DragosC]

Hi there. I'm just following up on our last message. Do you still need our help? Keep us posted. 
 

[Chasfliesu]

As Cristian suggested, I turned of the 'True Radiant' feature...I had no idea from the documentation that was how you turn of the 'pre-heat' function.  We'll see if that helps.  I'll also try his suggestion to reset>restart to see if it recalibrates.  I do get it that there can be differences between thermometers/thermostats, but 1-1.5 degrees C is not insignificant when it comes to turning the heat on and off...and since my experience is that it's 'inconsistent', so it's not like I can adjust the settings to accomodate for a difference of 1 -1.5 degrees since sometimes the diffeence is higher and sometimes lower than the readings on the other two thermostats which are consistent with each other...

[AnaM]

Hey @

I understand your point of view regarding the difference in temperature readouts, but as we said, it isn't a sign of concern when it's less than 2 C . However, we'll try to help you get more accurate readouts, so for now, monitor the thermostat for a few days and let us know if the situation improved. 

[DragosC]

Hi there. I'm just following up on our last message. Do you still need our help? Keep us posted. 
 

[george_t]

It's been a while since this thread was last updated so I'll go ahead and lock this thread. If you're still experiencing problems, please feel free to start a new thread and we'll be happy to help.