Nest Gen 1 unresponsive and not connecting to heat link

[Mukid]

Hi. I have an old Nest Thermostat that was installed about 6 years ago. I think its s Gen 1 product. In the last few days it suddenly became unresponsive and wouldn't wake on approach. After a bit of fiddling with the turn wheel it eventually seemed turned on but lost he connection to the heat link device. I've tried resetting both the nest and the heat link and they just won't pair neither will the nest connect to any wifi network. I did notice a low battery error when I went to settings and when I unplugged it from the base the unit shutdown straight away. The base is obviously connected to a charger that is mains powered so the unit does have mains power but I'm wondering if the problems I'm encountering are due to an end of life internal battery that doesn't hold its charge any more ? If this is the case then is my only option to replace the nest and the heatlink or could I just replace the nest and keep the existing heatlink? Are there any other recommendations to help get the existing unit working again ?

I have tried resetting the nest and the heat link multiple times and this doesn't seem to help.

Finally there is a button on the heat link, does this turn on both the hot water and the heating ? Is there any way to use this button to manually turn on just hot water ?

[Frustratedddd]

You need to know which model you have to start with, but an easy way to find out. Does the plate that holds the display have a blue or yellow spirit level? The 3rd Gen came out about 2015 you may well have that model.

[Mukid]

Hi. The base plate has a blue spirit level.

[Frustratedddd]

You have a 3rd Gen thermostat in that case,

I assume you have the display on the wall and powered from the Heat Link and not on a stand? What voltage is the battery saying currently in settings?

The battery can be changed, but it's a little tricky if your not that way inclined. Try plugging a micro USB in the back of the display for an hour or so, see if that helps.

You can buy a display on it's own, and the pair the new display with the Heat Link.

The button does turn on both, and that lets the system run 24hrs, which means you only have manual control, but would get the boiler fired up. Just to get the H/W working, I would drop the connection out of terminal 3 and make safe, then just the water will run. Assuming it's standard wiring.

[AlexD]

Thanks for reaching out here @Mukid and for all the details. I am sorry to hear you are facing difficulties with your thermostat and I would be happy to try and assist. 

You mentioned the base is connected to mains power. If the thermostat mounted on the wall and wired to the Heat Link, mounted on the wall but connected to power using a USB cable or mounted on a stand?

Thank you for the input @Frustratedddd , always appreciated. 

[Mukid]

Hi.

The thermostat is wall mounted to the base plate and this base plate has be connector on the back end which is plugged into the mains. The heat link is not wired to the thermostat so the connection between this and the nest is wireless. 

I've tried to go back to factory settings and re-initialised the heat link 6 digit code but this does not help and the unit just cycles trying to connect then eventually gives up. When doing this I have ensure the heatlink is in pariing mode and there is a blinking blue light when this happens. If I hold down the nest botton and get it to restart it does sometimes connect to the heat link and the light on the heat link will turn green, but within a few minutes the connection will drop and I'm back to square 1.

[AlexD]

Thank you for all the details. Usually this kind of behaviour is caused by some form of interference. It has been installed for some time so it is possible that things have changed in the environment. Did you add any electronic devices in the area that could be causing interference? 

Also, it has been some time, but do you happen to remember if originally the thermostat was paired next to the Heat Link or from the location it is on the wall at the moment? 

Also after all the options to try and pair back the display, do you see the Tech info one? If so access it and go to Power. Let me know what the battery and Vusb/Vin reading are. Low battery readings can also cause connectivity difficulties so if we can it is best top check for them.  

[Mukid]

Hi,

Nothing has changed in the environment that would cause this behaviour. The wifi router has been in the same place for the last 6 years and all the other house devices including this laptop are connected and working fine.

The heat link was installed by a qualified engineer as part of the new heating system we installed at the time so this was always a wireless link. It was not paired locally to the next to my recollection and the distance between them is just a few metres in any case. The themostat is in the dining room and the heat link is in the utilisy room next to the boiler.

The battery readings are as follows :

Battery - 3.658V

Vsub - 5.15V

Vin 0.00V

Lin 200mA (i)

What is your opinion - Anything else we can try to get this working or is it a case of replacement ?

[AlexD]

Thank you for the information. The battery level seems very low. Usually we expect to see it around 3.8 V at least. This is most likely the cause of the behaviour if nothing else changed in the area.

Do keep in mind that external factors can also cause interference in some cases, like in an apartment building for example if a neighbour sets up a new router on the other side of the wall where the Heat Link is. Just something to keep in mind even if this is not the case here. 

As the battery level drops under the thermostat will first lose connection to Wi-Fi, to try and reduce power usage and maintain connection to the Heat Link and if it keeps dropping it will also lose the connection to the Heat Link.

There is something we can try here, that is to directly recharge the display and see how it behaves. 

So take the display off the base and locate the micro USB port on the back of it. Charge it using that port and a power adaptor for 90 minutes. Once done, place it back, let it turn on and see if it connects back. It is possible that it is just drained for some reason and a direct recharge, instead of using it on the base, can help bring the battery back to the regular values and maintain them. 

Hopefully it connects back and if it does, go to Settings> Technical info> Power and take the power readings again. If it does not connect, access the power option again and take the readings from there. 

Let me know how it goes. 

[Mukid]

Hi. 

I charged the battery back up to just above 3.8V but was still experiencing issues so put it back on the base plate and left it for a while. I just went to check it now and the voltage was 3.892V. I tried the reset proc6for the heatlink and to my surprise it connected straight away. I was able to turn the hot water on and it seems to be waking on approach as well. 

It seems the unit is very sensitive to the battery voltage and it needs to be around 3.8V or more. Not sure why the battery discharged but it could be that someone pulled it forward slightly and it came off the base connector so was not trickle charging and drained. 

[Mukid]

Meant to say the voltage needs to be around 3.89V at least

[UanaC]

Thank you so much for letting me and my colleagues know that everything is back on track. Is there anything else I can help you with?

[Mukid]

Hi - The unit is functional now and can control the water and hot water. The only thing is that it doesn't connect to the internet though and doesn't seem to be able to see any networks. I'm not too bothered about getting it to connect to the internet and can use it on the scheduled settings.

[UanaC]

Understood. Can you please tell me if you see any code message when you go to Settings -> Network on your thermostat?

[UanaC]

Hello there! Just checking in with you. Did you see my previous message?

[Mukid]

Hi - I missed your previous message. When I check the NW settings I get a message saying the network maybe too far away or hidden. However it is not hidden as my other devices are connected to this fine. It doesn't seem to be able to see any network. I tried manually entering the SSID and PWD but this didn't work either.

[UanaC]

Hi there! I'm sorry to hear about this issue. Can you please answer to the following questions:

1. Do you only have one Wi-Fi network, or are there a few? If so, do any of them end in _ext?
2. Has your thermostat ever successfully connected to your network?
3. Were there recent network changes like a new router, network name, password or a recent move?
4. Are you controlling your thermostat from your app? If so, is your phone connected on a different Wi-Fi network?
5. What is the distance between the router and the thermostat?
6. Are your router settings set to the recommended Wi-Fi network and router settings for use with Nest products? Learn more here: https://goo.gle/2MJZPrV
7. What is the make and model of your router?
8. Are there devices or appliances (such as baby monitors, microwaves, cordless phones, etc) near the thermostat?

[Mukid]

1. I only have 1 wifi network in my home, but I can see my neighbours wifi networks as well when I doa  search on my phone.

2. When it was first installed, but at various times I have had to have the heating looked at and the power switch off so I didn't bother to connect to the wifi after these events since the scheduled times were acceptable.

3. No recent changes to the network

4. No

5. Circa 8m

6. Not sure and I don't want to mess with my NW settings since everything else including my work laptop  and TVs are all connected fine.

7. It's a Virgin Media Hub 3 router. Says the manufacturer is Arris on the bottom but can't see a model number

8. No. The Microwave is about 6m away.

[TudorL]

Thanks for all the information you provided. Would it be okay to send you an email on the address associated to your Community account? 

[Mukid]

Hi - Yes please do send email.

[Vladut]

Hi there, just checking in with you. Did you manage to check our last message?

[Vladut]

Hi there, just checking in with you. As you haven't replied, I'm gonna go ahead and close the thread. If you need anything else, please feel free to start a new one. Have a great day ahead!
 

[Mukid]

Hi - Happy or you to close the thread.

[UanaC]

Hello there! Just checking in with you. Did you see my colleagues previous message?

[UanaC]

Hello there! Just checking in. Is there anything else I can assist you with?

[Paul_R]

Hi there @Mukid! I just sent you the email, please follow the instructions in it and then give me a message here when you're done with it, okay?