2 thermostats, 2 heat links - 1 thermostat controls both heat links

[SebastiaanOr]

In my 2 zone home setup, I have 2 separate Nest Thermostats (3rd gen) both connected to a dedicated heat link (2 heat links in total) - each controlling a zone via Honeywell hub. All worked well, until switching power off and on for installing new lamps. 

Issue now is: one thermostat is triggering both heat links (the other thermostat seems to be ignored)

The thermostats connect to their heat link via wire AND wirelessly; wireless-only setup can't be configured somehow due to my frustration. My assumption is that both thermostats are connected via wire to their dedicated heat link, but that one thermostat is connected wirelessly to both heat links (and the other thermostat has no connection wirelessly).

Does anyone have a tip on how to enforce the thermostat to connect wirelessly to the heat link it is connected to by wire - or how to disable the wireless connection?

[Frustratedddd]

A quick easy fix is to fit one thermostat on a stand, but that's not the real answer.

I don't understand how the wired connections are doing this problem. The wired connection should only give you power to the display, not control of the system. You are correct, you should have a twin cable running from the heat links T1 & T2 to the base plates of your displays. This connection is just power for the display.

Check in Settings - Technical - Heat Link, on both displays, and see if they are the same Heat Link number.

Try to upload a picture of the connections on both heat links if you can.

[SebastiaanOr]

My assumption is that the wireless connection is the issue (1 thermostat connected wirelessly to 2 heat links).

Double checked the connections for both thermostats:

- Thermostat 1 (assumably controlling both heat links) is set to wired and wireless, and gives me details for 1 (!)  heat link

- Thermostat 2 strangely is (now) set to wired only - and does not give me any details for a heat link (only access hash)

@Frustratedddd if what you are stating is correct (wired connection is only for power), than thermostat 2 should not be able to control any heat link - though it is not 'complaining' that is does not have a connection; only that it is not able to 'update' the heat link with any firm updates if it is only connected via wire.

[Frustratedddd]

Assuming you have T1 & T2 connected at the heat link, that is correct and gives power to the display.

Thermostat 2 is your issue, as you should have an entry key there for the heat link. You can see the entry key on the heat link cover or by the left hand fixing screw for the number you need..

Check in Settings - Equipment, and see if you are able to connect wireless, see if it gives you an option.

Failing that, I think I would restart thermostat 2, and if that does not work reset thermostat 2.

Can you upload a picture of the connections for both heat links?

[DragosC]

Hi there @SebastiaanOr,

Thanks for reaching out and thanks for the detailed description. Thanks for your help, @Frustratedddd. 

Just to clarify on the matter, one thermostat cannot connect to 2 Heat Links, and same for the other way round. We'll need to check on them thoroughly. Also, a picture of the both Heat Links' wiring would be a really good starting point. Let me know when you've sent them. 

[SebastiaanOr · Accepted solution]

Thanks @DragosC and @Frustratedddd for your replies. Both thermostats showed different access keys for the heat links.

Followed @Frustratedddd process (more or less), by first trying to establish wireless connection as well (fails), next I did a full reset (same situation) and finally rest the heat link connected to Thermostat 2. After the reset, thermostat 2 was only connected by wire, but whole system worked as expected (issue solved).

Attached screenshots of the thermostat's info, main diff: Thermostat is connected by wire + wireless, and shows more info for heat link (thermostat 2 only showing entry key).

Thermostat 1

---

Thermostat 2Thermostat 2Thermostat 1/2

[DragosC]

Thank you very much for your description. You can compare the Heat Link serial numbers and the weave number. You can find the pairing entry code for the Heat Link next to the little screw that holds the case together. If it's connected to a display, the numbers should be the same. Let me know please. 

[SebastiaanOr]

Codes match (now). Not sure if they didn't before resetting the heat link...

[DragosC]

Thanks for letting me know @SebastiaanOr.  There's a good chance they weren't before. Please monitor the situation and let me know how's it going. 

[SebastiaanOr]

I think there is a learning in conversations above: Thermostats can be connected with Heat Link via wire only - wireless is optional.

Wire is not only for power, but for data as well.

Was wondering if you also think this is a plausible statement, @DragosC , @Frustratedddd ?

[DragosC]

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

[DragosC]

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!