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Nest thermostat won't connect to heat link

Community Member

I've read so many threads on this topic, and have done everything to reset the heat link and thermostat but the two will still not connect.  I've had the system for several years and its been fine and found the app said that the thermostat was offline.  It was however working from the thermostat itself but the app refused to recognise it, so I removed the device from the app, reset the thermostat and the heat link.  The latter is blinking blue but no matter how much I try with "replace heat link" and "reset pairing", nothing works with the repeated H71 error.

Please can someone help?  I've read about wiring it to heat link and then afterwards the wireless works but what cable do you use ?




Community Specialist
Community Specialist

Hi @tycariadus , thanks for reaching out here. I would be happy to try and assist. 


It is great to hear you already tried a lot of troubleshooting. 


A few extra things to try, if you haven't already, is to move the thermostat with the base connected to power closer to the Heat Link. Additionally turn off any Wi-Fi enabled device, including the router, and anything that could cause interference.


Make sure to reset the Heat Link 2 times, one after the other, by pressing and holding the button on it for 25 seconds. You should have a slowly blinking LED on it after. 


Try and go through all the options you receive after the H71 message one more time. Also before trying that, try and restart the thermostat by pressing the display for about 10 seconds. When it turns back on it will try and connect as well.


You can use a wired connection to form a setup and then remove it to have it wireless, that is true. You can use any single core wire with a maximum diameter of 2 mm. The connection between the thermostat and the Heat Link, using wires over the T1 and T2 terminals, only carries 12 V DC, so it does not require any heavy cables. 


Should you do this, have the thermostat connected over the wires, perform a factory reset, go through the setup and make sure that both wired and wireless connections are established and then remove the wired connection. Do make sure to stay safe if you are comfortable doing this and turn off the power whenever you do anything on the Heat Link wiring. 

Community Specialist
Community Specialist

Hi there. Just checking in. Do you still need our help?

Community Specialist
Community Specialist

Hello again. It's been a while since this thread was last updated so I'm going to close it. If anything comes up, feel free to open a new one.