How easy to DIY replace a Nest Heat Link?

Bendy_House

Yes, there's a cable from the heat link, tho' I'm surprised it's visible? Anyhoo, that cable will just be the control wire to the boiler to tell it to come on. It doesn't mean it's getting MAINS power.
I've just looked at a YouTube vid about setting up the Nest, and it shows 2 of AA batteries inside the heat link, and no provision for 'mains'. This will be so it can handle '2-wire' installations as well.
Look it up, pull off the cover (after cutting the power to the boiler), and check the batteries.

pinkteapot

Ah, from a Google it looks like it's the Nest E, not the Nest, where the Heat Link has batteries. I suspect ours is mains-powered because we have a power switch for them (like a switch for an immersion), and when you turn it off the Heat Link goes off (lights go off, stops working). We have one power switch covering both Heat Links, as they're next to each other in the airing cupboard. 

I have found a Heat Link repairer on eBay we can send it off to. They fully refund if they can't fix it so nothing to lose. When I try to remove it to send it off I will however double-check there's no batteries inside.

Next question... I'll obviously kill power at the fuse board before attempting to remove the Heat Link for repair. However, while it's away being repaired I'll want to turn power back on to keep the second Heat Link running. As I said, it's one power switch that powers the pair. But that means I'll have the wire loose that normally goes into the dead Heat Link and that wire will have power to it. Guessing I can't really leave it lying around like that for a week or so?! 

For interest, this is the setup (dead Heat Link is the one with no light): 



And there's a few generations of Nest which probably all look the same, but our Heat Link does look like the one in this video: https://www.youtube.com/watch?v=_GB1u3Z3xHg 

Bendy_House

That's great info, Pinkie. And I thoroughly enjoyed that YouTube video, as I'm sure you did

The miscreant component is a diode, then - I wonder if that's true of all the failures?

Your Heat Links are not like the ones I expected, which are the wall-mounted types. Yours are definitely mains-powered, and one of them does, indeed, appear deed.

You would be wise to also turn off at the fusebox, but that 'Heating programmer - leave on' switch should be enough to isolate it. Do you have means of checking mains voltages? Test screwdriver? What I tend to do is to turn off the power, remove the cover, test for a 'live', and then turn the power back on and check again. If a 'live' clearly shows when on, and disappears when off, you can be 99.9% sure it's all good.

Yes, you'll have bare wires when you remove the unit, and these will need making safe. The best way is to get a terminal strip where each wire can be attached and kept secure. Wrap in tape. Better still are Wagos, as these are fully covered and simply 'clip' shut. Tootstation do them in small quants, so perfectly affordable; https://www.toolstation.com/wago-221-3-way-compact-lever-connectors/p43878

Bear in mind that there will be a FEW wires for you to disconnect - I suspect at least 4, 2 of which will be the 'mains'. So, take photos, and label them if not colour-coded. A quick sketch is also good.

Please let us know how you get on - you seem to understand very clearly what you are doing.

coffeehound

Bendy_House said:

That's great info, Pinkie. And I thoroughly enjoyed that YouTube video, as I'm sure you did

The miscreant component is a diode, then - I wonder if that's true of all the failures?

Doh yes diode.  Bigclive has a way with words doesn't he?  He has done a second Nest repair and that was the same fault so it certainly looks like a weak point.

Swasterix

Skimmed the thread, so not sure whether it’s resolved, but see my thread from earlier in the year;

https://forums.moneysavingexpert.com/discussion/6320403/nest-thermostat-packed-in-boiler-help#latest

-Try calling Google first. Mine packed in earlier this year, and they sent me a new one free of charge, next day delivery, even though it was out of warranty. Think it’s a common problem. Worth a try!

pinkteapot

Swasterix said:

-Try calling Google first. Mine packed in earlier this year, and they sent me a new one free of charge, next day delivery, even though it was out of warranty. Think it’s a common problem. Worth a try!

I'm in shock!! I take back all my moaning about the Nest, and thank you very much for your story, which did prompt me to trying ringing Google...

Despite ours being out of warranty, they are sending an engineer free of charge to replace it! They've moved on from sending out parts and reimbursing fitter costs, to partnering with a heating repair company to come and do the repairs. Which suggests to me they do have a widespread issue with the Heat Link...

After speaking to them, you end up being emailed a case number to use when booking your engineer visit, which you do here: 
https://www.boxt.co.uk/boilers/boiler-repair

For future reference by anyone who finds this thread, you need to: 

1. Phone Google. This is the UK Help Centre link: https://support.google.com/googlenest/?hl=en-gb#topic=7029097 - go through thermostats, fix a problem, and keep clicking next and ignoring their suggested help pages until you get a 'call us' option and it will show you the phone number. 
2. They'll want your Nest serial number. It's on the back of the thermostat - the long number printed above a QR code. 
3. They'll take your details then ask you questions like "Have you turned the power off and back on?". They check you've tried everything on the Help site. 
4. While on the phone, they'll email you a case number. You need to write that and today's date on a piece of paper and take a photo of it next to the back of the thermostat (showing the serial number) as proof of ownership. You reply to the email, sending that photo, while on the phone. They want to see this before they'll authorise a free repair.
5. They then reply to you with the booking link above. 

Ta da!

I will reserve final judgement until we've been repaired, but I absolutely can't fault the service so far. Didn't have to wait to get through on the phone, and they offered to fix it with no argument. 

Genuinely curious now about how many of these Heat Links are dying... 

Anyway, thanks again! I was happy that I'd found a £30 repair service, but I'm even happier to be getting a free replacement! 

Thanks too to Bendy_House for the electrical tips. I now know what to do if I end up with an exposed bare wire in future.

Bendy_House

Promising result! Thanks Swasterix.

Google is, of course, doing what they should be doing. And they undoubtedly know the consequences of not doing so as well.

Cynical? Moi?

Swasterix

pinkteapot said:

Swasterix said:

-Try calling Google first. Mine packed in earlier this year, and they sent me a new one free of charge, next day delivery, even though it was out of warranty. Think it’s a common problem. Worth a try!

I'm in shock!! I take back all my moaning about the Nest, and thank you very much for your story, which did prompt me to trying ringing Google...

Despite ours being out of warranty, they are sending an engineer free of charge to replace it! They've moved on from sending out parts and reimbursing fitter costs, to partnering with a heating repair company to come and do the repairs. Which suggests to me they do have a widespread issue with the Heat Link...

After speaking to them, you end up being emailed a case number to use when booking your engineer visit, which you do here: 
https://www.boxt.co.uk/boilers/boiler-repair

For future reference by anyone who finds this thread, you need to: 

1. Phone Google. This is the UK Help Centre link: https://support.google.com/googlenest/?hl=en-gb#topic=7029097 - go through thermostats, fix a problem, and keep clicking next and ignoring their suggested help pages until you get a 'call us' option and it will show you the phone number. 
2. They'll want your Nest serial number. It's on the back of the thermostat - the long number printed above a QR code. 
3. They'll take your details then ask you questions like "Have you turned the power off and back on?". They check you've tried everything on the Help site. 
4. While on the phone, they'll email you a case number. You need to write that and today's date on a piece of paper and take a photo of it next to the back of the thermostat (showing the serial number) as proof of ownership. You reply to the email, sending that photo, while on the phone. They want to see this before they'll authorise a free repair.
5. They then reply to you with the booking link above. 

Ta da!

I will reserve final judgement until we've been repaired, but I absolutely can't fault the service so far. Didn't have to wait to get through on the phone, and they offered to fix it with no argument. 

Genuinely curious now about how many of these Heat Links are dying... 

Anyway, thanks again! I was happy that I'd found a £30 repair service, but I'm even happier to be getting a free replacement! 

Thanks too to Bendy_House for the electrical tips. I now know what to do if I end up with an exposed bare wire in future.

Excellent! Happy to help and glad you are (hopefully) sorted!

Google do come in for some stick at times, and it’s often warranted! But fair is fair, you can’t fault the way they are handling this issue (even if it is a common fault). 

Swasterix

Bendy_House said:

Promising result! Thanks Swasterix.

Google is, of course, doing what they should be doing. And they undoubtedly know the consequences of not doing so as well.

Cynical? Moi?

Absolutely agree, they are doing what they should be doing! But out of warranty, they don’t have to do it. Fair play to them I say, but I do share your cynisism!!

Sadly I’ve been having the opposite experience with Siemens over an ongoing issue with a washing machine… I’ve found that companies rarely do anything outside of their legal obligations. One for another thread though!

pinkteapot

Yep, absolutely credit where it's due to Google, as we're out of warranty so they didn't have to do anything. 

They must be really desperate to win the battle to become the dominant smart home device provider.