06-05-2025 01:04 PM
Hi, I am having trouble with heating, I use the Nest 3rd gen thermostat that is wired and connected to Heatlink (we are in Central Europe). For heating, I use a condensing boiler—Viessmann (supporting opentherm). After its installation (November 2024) everything was ok until just recently when the hot weather arrived. The problem is that I use Nest to regulate radiators, which worked perfectly fine; they turned on once the temperature dropped. But now, I realize that the radiators are heating when I turn the hot water on, for instance, while in the shower, the radiators turn on. Since then I've turned the autosense off; all smart features on Nest that I know of are disabled, and the temperature is set to 13°C/55°F, but from time to time I can still feel that the radiators are heating. I have no idea what to do. Any thoughts? Here is a picture of how the Heatlink is wired.
06-07-2025 05:22 AM
The first thing I would do is switch the system off NOW and get the installer back immediately!!!
Reason, cross polarity will NOT help!!! [See Picture] - Live Neutral round the WRONG way!!!
When they come back, ask them to put the cable inside the Heat Link rather than leaving the cores outside!!
You could also ask them to perhaps connect an earth wire, as the feed looks just a 2 core, but that could be incorrect on my part as I cannot see the cable 100%!
06-08-2025 05:19 PM
Hi MN74,
Thank you for posting in the community.
I understand that your radiators are heating up even when you only intend to use hot water, despite your 3rd gen Nest Learning Thermostat (NLT) being set to a low temperature and smart features disabled. I appreciate the important details of your installation you've provided and the picture of how the Heat Link is wired. No worries, help is here.
Thank you Frustratedddd for your contribution.
Before I start providing assistance, I would appreciate it if you could answer the following questions:
Please keep me posted.
Best regards,
Virna
06-08-2025 11:53 PM
@virnabAre you serious? Look at the connection polarity!!