Heat link Gen 3 failed

[TomBrock]

Hi my heat link gen 3 has stopped working, it has power when connected via the micro USB but when removed has no power and it will not connect at all to the thermostat nest.

I've tried holding the button in multiple times to reset the heat link with the cable plugged in. It wont connect to the nest with the nest directly next to it.

When I remove the usb connection it has no power at all.

I've had the system a little over a year and it was installed along with the Vaillant boiler we had fitted.

If there's anything I can try any advice would be appreciated.

Thanks

Tom

[AlexD]

Hi @TomBrock.

Yes, when connected with the micro USB cable the Heat Link will not connect to the thermostat, it is not designed to be powered by that cable. It requires the high voltage provided over the L/N terminals. Even if the LED lights come on, it will not work as expected when connected with USB power. 

If you have not already make sure to check all the breakers and switches at the location, no make sure nothing has tripped. Also check to see if the boiler has any separate switch or breaker, as sometimes they do. If it all looks good and nothing has tripped, cut the power to the Heat Link for a few minutes, if you're comfortable in doing so, then turn it back on. See if it has any reaction after when you press the button on it.

Make sure that the USB cable is disconnected when you try to power cycle the Heat Link. 

Regards, 

AlexD

[TomBrock]

Thanks for the reply, I've disconnected the heat link for a minutes and tried to button but got no response, no lights etc.

I checked the fuse board and nothing has tripped, the boiler itself is on I've tried turning that off and on. I don't think the boiler has a seperate breaker as it all the breakers are on and it's working. Unless there's some kind of internal breaker just for the heat link?

It looks like the boiler isn't providing any power to the heat link, once the usb is disconnected it turns off and wont turn back on. 

Thanks

Tom

[AlexD]

You can just check to see if the boiler has any display or LED that comes on. That would indicate that it is receiving power.

A few more things we can check:

1. Was the thermostat installed by a Nest Pro or by a regular installer?
2. Are you seeing any message on the thermostat and/or the app?
3. Have you had any recent power cuts in your area?
4. Have you recently had service or maintenance on your electrical, plumbing, or heating system?

[TomBrock]

The display screen on the boiler is on so that is working.

1. It was installed together with the Vaillant boiler by a Vaillant engineer.

2. The message I get on the nest is the H71 error message.

3. No power cuts that I know of.

4. It hasn't been touched since it was installed.

[AlexD]

Thanks for the info @TomBrock.

To investigate this further please fill out this form so we can gather your details securely, and let us know once you've done it https://bit.ly/3oVDg4g . Make sure to include the display serial starting with 09A, the email associated with your Nest account and your full post address. Make sure to include your forum username under the "Social handle" field of the form, without it would be impossible confirm which form submission is yours. 

[TomBrock]

Thanks I've filled that out.

[AlexD]

Thanks @TomBrock . Me or one of my colleagues will reach out to you over email as soon as possible.