NEST THERMOSTAT ONLY WORKING ON MANUAL MODE

[Knight2]

Hi all,

Help needed please! 

I've recently installed two learning thermostats as I have two zones in my house. The heatlinks work as I'm able to manually turn on the heating but that's all i'm able to do.

The thermostats won't work unless in manual mode - they say they don't have power and will shut down, however will boot back up and work continuously whilst in manual mode but the minute i turn it off from manual, it stop talking the boiler and loses power, then eventually switches off!! 

Does anyone have ideas as to what the problem could be?

Thanks in advance

[Frustratedddd]

A picture of your Heat link connection could help, as this may be a wiring issue.

Are you wired direct from the Heat link to the stat, or powered from a USB on a stand?

[Knight2]

Hi, i've just uploaded the pictures of the heat links. we are direct from heatlink to thermostat, We've used the same set up from the previous thermostat that wasn't smart and worked for 7 years

[Knight2]

[Frustratedddd]

Well from what I can see, unless the Grey or black wire is not live, you do not have a feed to the Heating contacts!

Where does the Grey wire go?

Where does the Black wire go?

[Frustratedddd]

Oh Dear!!!

Your displays are 12v ONLY, IF you have connected the Grey and black to the display, REMOVE NOW!!!

[Frustratedddd]

[Frustratedddd]

Can you tell me where the wires go?

The Blue and Brown are obvious, but where do the Black and Grey go?

[Knight2]

sure. the grey one is going into '2' and the black one is going into '3'

[Frustratedddd]

I can see that, but where do they go the other end??

[Knight2]

into the floor - we have all the wiring from the old thermostats there. They then feed to the boiler. The displays are wired with the following:

[Knight2]

the grey and black only go into the heatlinks - not the thermostat display

[Frustratedddd]

OK, let's start again!

Where does the Brown come from? - ie: Live Feed?

Where does the Blue come from? - ie: Neutral?

Where does the Grey come from?

Where does the Black come from?

Just remember the display is ONLY 12v, do NOT connect 240v to it. Should you be in doubt at present, turn of now until we get this sorted.

[Frustratedddd]

Where do those 2 cores go to?

The Brown and Grey at the display end?

[Knight2]

they were going into the base plate as power but it doesn't provide enough power for the unit to work

[Knight2]

bit annoying but i'm not sure - i had it installed by a professional plumber who has fitted nests and hives so i'm confident it was done correctly. i'm currently waiting for a voltage checker so should be able to check the wires this evening! Apologies i'm not much help on the wires

[Frustratedddd]

Put it this way, normally you would have a link from Live to term 2, but I do NOT want to suggest anything until you know the wiring. I need to know the connections 2&3 where they go.

Just make sure you do NOT get 240v to the display as that's expensive!!

[Knight2]

ok fair point - i will look into the wires and come back to this thread - it's defo not 240v as when they were connected to the base plate, the technical information showed that the power was 3.4v (google told me that it needs to be 3.8v minimum) 

[Frustratedddd]

Why is the Heat Link on the floor if connected by the plumber?

[Knight2]

I asked for it not to be connected onto the wall until i know the units work.. As the issues were happening straightaway

[AlexD]

Hi @Knight2 , thanks for reaching out here. I see you have been looking into this with @Frustratedddd , thank you for all the assistance!

You can have the display mounted wirelessly, powered with a power adapter and a cable or have it wired to the Heat Link. In that case you need to have wires from T1/T2 from the Heat Link to the thermostat base, it also has T1 and T2 terminals. This carries 12V DC. You can have a look here to see some different installations and wiring setups. 

Make sure to let me know if you need any further assistance after you check your wiring. I would be happy to try and assist. 

To add a little extra information. When checking the power on the display you would see around 3.8-9 V for the battery and either Vin of around 12V if it is wired to the Heat Link or Vusb of around 5V if using a cable and adapter. 

[OannaCG]

Hi there! Just checking in, did you manage to see our message above?

[UanaC]

Hey there, I haven't heard from you in a while so I'll be locking this thread. If you have any new issues, updates or just a discussion topic, feel free to start a new thread in the community.

Thanks, Oana.