Why is Nest calling for heat when room temp is much higher than temperature set on stat - 2

[bob_a_builder]

A follow on thread from 
https://www.googlenestcommunity.com/t5/Nest-Thermostats/Why-is-Nest-calling-for-heat-when-room-temp-...

I have not received the email from DragosC, which he referred to in the last post on the previous thread
Spam and Junk folders have been checked

I also never received the email he referred to in a earlier post,
i.e. this one
"Your Google Support Enquiry: Case ID [6-3486000031999]


 

[CristianC]

Hey @bob_a_builder,

I checked your case and Dragos sent you an email yesterday. Have you received it yet? 

[bob_a_builder]

 No - I haven't !

[CristianC]

Thanks for the details @bob_a_builder. If I understand correctly, your issue is that the thermostat starts heating ( to reach 9 C ) when it's not supposed to. Based on your Energy History, it looks like expected behavior. What is the temperature in your home when this happens? 

[bob_a_builder]

Its not the behaviour I'm expecting !

If you look at the earlier thread of the same title 
https://www.googlenestcommunity.com/t5/Nest-Thermostats/Why-is-Nest-calling-for-heat-when-room-temp-...

You will see that there was also a screen shot of a graph of that rooms temperature.  which shows the room never ( well once ) goes below even 17c let alone 9c
I set it to 9c  at 22:30 to effectivity turn the heating off for the night

So once the 9c setting comes into force @ 22:230, there should be no further calling for heat 
Yet every other night or so you will see a bar indicating that the Nest HAS called for heat after 22:300
I can see no reason why that would be the correct/expected behaviour ?

Still no email recieved from DragosC  BTW




So the room has been heating to 21.5 since 19:00

[CristianC]

Hey @bob_a_builder. Checking your Energy History, everything is as expected. Your thermostat turns on the heating so it doesn't reach 9 C. Turning off True Radiant will resolve this - your heating will only start when the room temperature reaches 9 C. 
 

[bob_a_builder]

"Your thermostat turns on the heating so it doesn't reach 9 C."
Sorry that doesn't make sense to me  - the room is already at 21 C  and now I've asked for a 9c at 22.30 
I can understand True Radiant ( in the morning) calling for heat early to ensure the room is at the required temperature at the set time requested  - So it can 'learn' how much earlier it needs to start heating to achieve the required setpoint.

I really can't understand why True Radiant would call for heat when the target temperature is way below the current temperature 
Why has it not 'learnt' that to achieve 9c from an existing room temp of 22c , (in the case of my room)  it needs to do nothing for a very long time, but instead decides to call for heat a few minutes after the 22:30 set point   - Thats my point  - and to me that sound like a 'bug' in the system

You may be able to see more clearly defined data points than the Energy Monitor screen shows us users.  But from this chart, to my mind the calls for heat after 22:30 are un-necessary 

[AlexD]

Thank you for the extra information @bob_a_builder . Would you mind also taking a picture/screenshot of the schedule you have? This way I can get a better idea of the expected temperatures across the day and their times. 

[bob_a_builder]

My schedule is as follows (every day)

19.5 deg C  @ 07:30
21.5 deg C @ 19:00
9 deg C  @ 22:30

[bob_a_builder]

There is more related info in the 1st thread on this subject
https://www.googlenestcommunity.com/t5/Nest-Thermostats/Why-is-Nest-calling-for-heat-when-room-temp-...

[AlexD]

Thank you. I see that each day the thermostat starts and ends with the same temperature. Of course in the morning as the 19.5 degree setpoint is approached it would be expected with True Radiant active that the system would activate before the setpoint. 

You do point out correctly that when looking at the energy history it shows the 21.5 range dot and then the 9 degree one for when that setpoint is reached. Since the location was maintained at 21.5 once it switches to 9 you would expect the history to look like on Thursday 24th for all days.

Any orange bars after an orange temperature bubble in the history would generally indicate an activation for that temperature, in this case 9. Since the location should have been kept at around 21.5 until then of course it would generally not be expected that the temperature would just drop suddenly under 9. 

Just to confirm, the thermostat is not close to a window, door or some source of cold air correct? 

[bob_a_builder]

Yes - I can see the TrueRadiant function working well in the morning as room goes from low to high - I have time limit set to 1 hour and I can see variable start times prior to 7:30 within that 1hr window - so it would be a shame to have to switch that feature Off to fix the current issue 

Position of  sensor :  It depends on you definition of close - but its about 2 metres from nearest window

And as you say it would be highly unlikely for the room to cool that quickly (minutes) after being at 21+  to trigger a call for heat to maintain 9c

[bob_a_builder]

This shows the reading for the temp in room - sensor at same position as nest

A longer term view - the lowest temp recorded in the graph below  is 17c

[DragosC]

Thank you. We've sent the case to our senior support team. We'll be right back with you. 

[DragosC]

I'm back from the consultation with our senior support team and they've advised us to kindly ask you to try a few steps and answer to a few questions so I can document the case and send it to our engineering team:

• Restart the thermostat from Settings > Reset > Restart 
• Nest app version from your phone's settings :
• Mobile device make & model?
• Mobile OS version?
• Mobile service provider?
• A picture from the thermostat's settings > Technical info > Network
• A picture from the activity history from the Nest app 
• A picture from the Detailed Energy History from the Nest app 
• A picture of an internet speed test next to the thermostat with the results

[bob_a_builder]

1. Restart the thermostat from Settings > Reset > Restart - DONE
2. Nest app version from your phone's settings  - 5.68.0.12
3. Mobile device make & model? Mobile OS version?   Oppo A72,   Android 11 
4. Mobile service provider?  Lebara  which uses the Vodafone network
5. A picture from the thermostat's settings > Technical info > Network - See next post
6. A picture from the activity history from the Nest app - See next post
7. A picture from the Detailed Energy History from the Nest app - See next post
8. A picture of an internet speed test next to the thermostat with the results See next post

[bob_a_builder]

Note : Todays detail history doesn't show any good examples of the issue - please refer to the previous posts for better examples

[DragosC]

Thank you very much. I'll add this information and consult with the engineering team. Once I've got word from them, I'll let you know. Have a good one! 

[DragosC]

Hi there. We've seen that the case is being handled by a senior support agent. In this case, I'll have to close this thread. Should anything else come up, please open another thread and we'll take it from there. Have a good one and stay safe!