Nest Wiring Help Please

[Nibber]

Hello
I have a secure 302 channel wireless receiver connected to my boiler it just fitted over the standard backplate when I removed the old programmer some years ago, it is paired with a wireless thermostat, I think I linked two connections together in the central heating wiring centre but can't remember which ones, so everything work ok at the moment but I want to replace the thermostat and receiver with a Nest to control Heating And HW

This is from the receiver manual

This is what I have when I remove the old receiver above

So if I move the L N Wires to the correct L N on the heatlink and link L to 2 and 5

No 4 above is Heating and No3 HW

So yellow no3 above goes to no6 and blue no4 goes to no3 is this correct?

I want the Nest to connect via Wireless to the heatlink is there anything I am missing here

Thank you for reading and any advice
Nibber

 

[stem]

It's a while since I saw one of these, but assuming that SSR302 'Channel 1' is controlling the central heating and 'Channel 2' the hot water, what you propose looks correct to me.

There is very limited space inside the Nest Heat link, for wires, but you are lucky, in that there is a metal back box (make sure it has an earth connection) already in place. I would terminate the wires in there, fit the Heat link over it and then just bring the required wires to the Heat link terminals. If you are going to use terminals T1 and T2 to power the Nest thermostat, the Heat link will also need an earth connection made to its earth terminal. [Even if powered from the Heat link, there is still wireless communication between the Heat link and thermostat]

As the SSR302 is already working in conjunction with a wireless thermostat, there is no additional wiring modification to be made. You already did that when the SSR302 was installed.

 

[Nibber]

That's great, Thank you

 

[ianmcd]

Even if powered from the Heat link, there is still wireless communication between the Heat link and thermostat]

Hi @stem , I too always thought tha, but there was apost a while back on here about this and someone posted a doc from nest that said when the thermostat power is taken from the heatlink,the coms are wired and no longer uses wireless to communicate, tried to find the post but too many nest posts, the doc was nest advising to do this if the wireless connection kept dropping out, as said was a new one on me too

 

[stem]

Ah, interesting. My conclusions were based on. This diagram in the Nest manual that when discussing and showing the WiFi connection, shows it both hard wired wired and communicating wirelessly to the Heat link at the same time.

T1 & T2 are simply marked as a 12v DC power in their diagram.

I guess because part of my work is writing bespoke technical manuals, I'm a bit fussy that drawings are correct, clear and unambiguous. And it's not like Nest have to write a new manual for each installation.

Also, I once fitted an early gen 3, with the thermostat wired to T1 & T2 it worked fine for 6 months then the user (software engineer) told me he had been loosing communication between the Thermostat and Heat link. The Heat link had replaced a old programmer in the kitchen, and his wife had moved their large metal microwave directly in front it. He told me that moving the microwave had solved the problem. So even though hard wired, it still seemed to be communicating wirelessly.

However, if someone has a obtained an answer from Nest directly then that will be correct of course.