topic Re: Lost connection from Thermostat to head link H71 in Nest Thermostats

Lost connection from Thermostat to head link H71

philLearmont — Sun, 20 Mar 2022 13:59:42 GMT

On of my two heat link/thermostat pairs have lost connection.

there is power to thermostat and heat link.

Heat link shows constant yellow and does the same on reboot

Thermostat will not connect and shows error message h71 (of which I can find NO documentation)

I have power cycled (physical disconnect) the heat link - no change.

Affected thermostat has limited options now which consist of show tech info (it is connected to the WIFI etc.) , retry connection (always fails with h71) or replace heat link (impossible as cannot get the heat link to flash blue).

Is it terminal or is there something I can do?

Re: Lost connection from Thermostat to head link H71

philLearmont — Sun, 20 Mar 2022 14:01:35 GMT

Type - meant "Heat Link" not "Head Link"... my bad.

Re: Lost connection from Thermostat to head link H71

philLearmont — Sun, 20 Mar 2022 20:43:51 GMT

From reading other threads there may be some info required on what the thermostat can see from its power settings. I have it free standing, plugged in.

Battery: 3.932V

Vusb: 5.06V

Vin: 0.00V

lin: 200mA (c)

Re: Lost connection from Thermostat to head link H71

DragosC — Tue, 22 Mar 2022 14:27:03 GMT

Thanks for letting us know @philLearmont,

I put in here some steps to help you connect back the thermostat with the Heat Link. The steps need to be fulfilled in this order only.

Before following these steps make sure of the following:

- The thermostat is connected to the base and to a power source and it's getting power (You can check in the "Technical info" option, and after that in "Power", the battery needs to be above 3.8 in order to maintain a constant connection with the Heat Link, however, if it's not, let it charge until it is).
- If you have the possibility (the thermostat is on a stand), bring the thermostat and the Heat Link as close as possible only for the pairing process, after that, you can move them anywhere in the 30 meters radius

1. Gather the 6-digit entry key located on the bottom side of Heat Link's case, near the screw that holds the case together.

2. Select the option "Replace Heat Link" on the thermostat (you will have a message saying that the thermostat failed to connect wirelessly to the heat link, you just need to continue and you will receive a screen with 4 options: check again, reset pairing, replace heat link and technical info, the correct option in the third)

3. Put the 6-digit entry key in there but don't confirm it. Just write it there and stop when you see the word "Connect" highlighted.

4. Press the "Nest" button on the Heat link and hold it for 45 seconds until you see a slowly pulsating blue light on the Heat Link. After that, wait about 5 seconds and press and hold it again for another 45 seconds until you see a slowly pulsating blue light on it.

5. Go ahead and press connect on the Thermostat's display and wait about a minute. You shall see the message "Heat link connected wirelessly" and the Heat Link's light shall be solid green. That means the devices are connected and working.

Re: Lost connection from Thermostat to head link H71

philLearmont — Tue, 22 Mar 2022 16:49:29 GMT

Brilliant, clear, simple instructions which worked first time - thank you.

I will gloss over the google help - unspeakably bad. HOWEVER....

After re-connecting and checking it was working by putting the heating on, within 5 minutes - the same H71 error!!!

Is my hardware shot? I only had it installed on the 25th November

Re: Lost connection from Thermostat to head link H71

DragosC — Tue, 22 Mar 2022 17:01:47 GMT

Thank you. If it connects the first time and then it disconnects, that might be because of the wireless interference in the house. Please read the following article thoroughly: https://bit.ly/3e9exao

Re: Lost connection from Thermostat to head link H71

philLearmont — Wed, 23 Mar 2022 08:06:43 GMT

Thank you. I repeated the exercise and moved the thermostat closer to the router. So far so good but going to keep the thread open for a couple of days to see if it holds.

your advice is greatly appreciated

Re: Lost connection from Thermostat to head link H71

DragosC — Wed, 23 Mar 2022 11:22:05 GMT

That's great news. Thanks for letting me know. Sure, no worries. Keep us posted.

Re: Lost connection from Thermostat to head link H71

DragosC — Fri, 25 Mar 2022 11:33:31 GMT

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

Re: Lost connection from Thermostat to head link H71

DragosC — Mon, 28 Mar 2022 08:17:02 GMT

Since I haven't heard from you in a while, 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!