Google Nest Thermostat H73

[WillemBraem]

Dear Community,

I have a friend were I helped installing the Nest learning thermostat Gen3, it has worked for over a year without any issues. It's connected through opentherm and the heater is a Remeha Calenta (Oil).

Since last week the thermostat is giving the error H73 saying that it's unable to communicate with Opentherm device. I have checked the heater and its not giving any error code and is functioning normally (needless to say but it's powered on as well).
Here is a list of things i have already tried:

• Complete reset of heatlink
• Switched off the power for the heatlink and heater for half an hour
• Complete rewire of the heatlink to the heater and thermostat display
• Installed the old Remeha thermostat again and this was working fine without any issues.
• A certified installer for the remeha heater has stopped by and has confirmed that there is nothing wrong with the heater.

I'm at a loss here and don't know how to move forward with resolving this issue.

Any help would be greatly appreciated.
Thanks in advance.

Kind regards,

Willem

[AlexD]

Thanks for reaching out here @WillemBraem and thank you for all the details. I'm sorry to hear your friend is facing difficulties with their thermostat and I'd be happy to try and assist. 

You are correct about the H73 message. That indicates that there is a connection between the Heat Link and the display but the OpenTherm connection is not detected. 

The steps to try in this case would be:

1. Ensure that power to the boiler is still present.
   1. Turn on Manual mode. Press the button on the Heat Link and you should see 2 additional LED lights come on
   2. If power is present on the boiler, restart the Nest thermostat Heat Link. Press and hold the button on the Heat Link for 10 seconds and let go.
   3. Should this fail, power cycle the boiler at its On/Off switch. Which seems you already tried.

If you went through all these steps let me know and if so, would it be ok if I reached out over the email attached to your account here? I'd want to create a case and have a chat with our senior colleagues on this. 

[WillemBraem]

Hi Alex

Thank you for your response!
I will try these steps again to make sure we have this covered. afterwards i will get back to you!

Definitly OK to reach out through my email address in case you already want to move forward there as well.

Thanks.
Kind regards,

Willem

[Paul_R]

I have just sent you that email @WillemBraem . Let me know when you completed the steps from Alex and also when the form from the email has been submitted.

[WillemBraem]

Hi Paul

This sunday i will stop by my friends house to check the steps again and will get back to you!

Thanks!

[LarisaL]

Hi there! We'll be waiting for your message!

[UanaC]

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

[WillemBraem]

Hi there!

I just stopped by my friends house and filled out the form with the details. it's filed under # for reference.
I have also tried the steps provided again but with no luck.

How will we go forward from here?

Thanks!

[TudorL]

Thanks for letting me know. If it's good for you as well, we can continue the conversation by email. I'll send you one where you can reply right away.

[AlexD]

Hi, I wanted to check in. Did you receive my colleagues email? 

[WillemBraem]

Hi Alex,

Yes i'm in communication through my friend (case logged throug their email).

Thank you for checking up.

kind regards,

Willem

[AlexD]

That's great to hear. If anything else comes up that I can try and assist with, make sure to let me know. Have a great day ahead! 

[Paul_R]

Hi there. I'll have to close this conversation for the moment, but if anything else comes up, please feel free to reach out. Have a good one and stay safe!