2nd Generation Nest Heat Link to Baxi Duo-Tec 28 HE

[PAUL HOGG]

Hi new to this forum and seen some good detailed posts on commissioning my Nest Heat link/thermostat.

I have carried out the following.

1. Removed existing link cable in Boilers terminal block - see attached picture
2. Installed and wired the Heat link to the mains (240v) and connected terminal points 2, 3 to the link cable i have removed in point 1
3. i installed and connected the thermostat and everything looks good.
4. if i modify the temperature either directly on the fixed NEST thermostat or via the linked smart phone i hear and see the Heat link click/flash
5. i assume this is the device recognising it should send a signal to the boiler an fire it up, it doesn't
6. if i put the link cable back in - ie disabling the NEST the boiler fires up fine.
7. After investigation i found that the existing setup had a 24 Hour Programmable Room Thermostat single channel connected (see attached).
8. again after researching the internet this is a primitive connection (RF/wireless) thermostat which has a receiving device connected to the boiler.
9. i made the assumption that this thermostat may overide and stop the NEST working therefore i removed the connecting cable from the fitted RF device to the system motherboard and removed batteries from thermostat,
10. i reconnected the nest and tried changing the temperature, again the Heat link reacted and i heard it click and the LEDs show that it was heating, but the boiler did not fire up.


Is there anything iam doing wrong or a way to test further.

Thank you in advance.

 

[Deleted member 267285]

Please post photo’s of boiler wiring, nest wiring and boiler front panel.

 

[PAUL HOGG]

Hi

Thank you for your reply.
Attached pictures as requested.
i have also checked with my neighbours boiler (same model) and attached the picture MY BOILER which shows there boiler with no programable thermostat.

if i replicate this with my boiler ie put connectors back as in my picture would the HEAT LINK work.( removing RF/wireless thermostat)

It would make common sense i guess as i previously had two thermostats in situe.

thank you in advance.

 

[ianmcd]

It would make common sense i guess as i previously had two thermostats in situe.

2 thermostats , was that one upstairs and one downstairs ?

 

[Deleted member 267285]

2 thermostats , was that one upstairs and one downstairs ?

I think it’s possibly more of a case of the old one was left in as well as the new one?

Not sure if this is relevant or why it will not work, on the photo at boiler it appears that the earth wire is being used as a neutral, yet nest end shows neutral wire and earth wire?

 

[PAUL HOGG]

HI

Yes i dont the power issue is the problem, i acknowledge that the installer has used the earth as a neutral.

So basically the call to heat is not working from the NEST heat link - they have used 1.5 flat twin and earth , solid cable rather than strand, would that cause an issue.

is there any further tests i can carry out ?

 

[PAUL HOGG]

And yes the old RF receiver was left in, i have removed it and re linked the blacks and isolated the Neutral and live, still no joy.

 

[Deleted member 267285]

You could try disconnecting the wires that were for the old receiver, if that doesn’t work, maybe place a link on two switching ports on Nest, if it fires up, probably a faulty nest?