Need advice from a sparky (Nest Thermostat)

16
Found 7th Jan 2016
I need a sparky to shed some light on this situation..

I bought a Nest, and went through the website to book a Pro Installer to come fit it to my boiler. After an hour or so of tinkering, he explained that the Nest was incompatible with my boiler, suggested I return it and left. A couple of minutes later, he sent the following email:

"Saunier duval combi boiler has its own plug in wireless thermostat. No connection for external control on boiler apart from a 24v connector but nest requires 240v. Did not want to try as could blow pcb"

Perhaps someone more versed in this area can explain this a bit better... surely the boiler is connected to mains (240v), correct? My boiler is a 'Isofast Condens F35E' (manual with tech spec available here: http://www.ultimatehandyman.org/PDF/Saunier-Duval/Saunier-Duval-Isofast-Condens-F35E-Installation-manual.pdf).

Is it *really* incompatible?

16 Comments

Original Poster

dkl_uk

Go here and ask again:http://www.ultimatehandyman.co.uk/



Thanks, will do! Never heard of the site, so I've bookmarked it for future use.

It can be done but with an external relay and new feed , but of messing about , but it can be done.
I would expect him to be on a fixed fee per unit installed so not really in his interest sadly to go beyond what he's paid to do.

There was a thread on there with a similar issue. Short story is the boiler instructions suggested nothing should ever be plugged into the external wiring but it was resolved within a day by someone with sufficient knowledge.

Original Poster

peacehavenowner

It can be done but with an external relay and new feed , but of messing … It can be done but with an external relay and new feed , but of messing about , but it can be done.I would expect him to be on a fixed fee per unit installed so not really in his interest sadly to go beyond what he's paid to do.



Hmm. I wonder if it's worth bringing someone in. Shame, I already paid Nest for their Pro Installation service.

Nest doesn't require 240v, you could try putting it into the 24v but i'd be amazed if it worked (it won't do any damage). Are you sure the boiler doesn't have a switched live on the PCB (it will normally have a link wire from it to the permanent live).

The boiler manual is really crap, hardly suprising given its a Saunier Duval X)
Edited by: "themorgatron" 7th Jan 2016

Original Poster

themorgatron

Nest doesn't require 240v, you could try putting it into the 24v but i'd … Nest doesn't require 240v, you could try putting it into the 24v but i'd be amazed if it worked (it won't do any damage). Are you sure the boiler doesn't have a switched live on the PCB (it will normally have a link wire from it to the permanent live).The boiler manual is really crap, hardly suprising given its a Saunier Duval X)



No choice re: boiler, I'm afraid! :P

Not sure what the boiler has and doesn't have. Was not here when the Pro installer came to see it, and not really sure where to look in the boiler (can't even remove the cover to see where the wires are!).

Would love to try and set it up myself (it's sitting in a box waiting to be collected by UPS tomorrow to be returned back to base), but not sure where to begin!

qwertymz

No choice re: boiler, I'm afraid! :PNot sure what the boiler has and … No choice re: boiler, I'm afraid! :PNot sure what the boiler has and doesn't have. Was not here when the Pro installer came to see it, and not really sure where to look in the boiler (can't even remove the cover to see where the wires are!).Would love to try and set it up myself (it's sitting in a box waiting to be collected by UPS tomorrow to be returned back to base), but not sure where to begin!



Ignore the possibility of a switched live, reading the manual again the mains cable has to be bought from Saunier themselves so it's obviously a strange connector to the PCB. I'm guessing the 24v will be a special connection also.

Original Poster

themorgatron

Ignore the possibility of a switched live, reading the manual again the … Ignore the possibility of a switched live, reading the manual again the mains cable has to be bought from Saunier themselves so it's obviously a strange connector to the PCB. I'm guessing the 24v will be a special connection also.



i.e. incompatible with the Nest?

qwertymz

i.e. incompatible with the Nest?



I would connect it up to the 24v side of the boiler, I can't see why it won't work.

Original Poster

themorgatron

I would connect it up to the 24v side of the boiler, I can't see why it … I would connect it up to the 24v side of the boiler, I can't see why it won't work.



I would try... Expect I can't find any wires. All the guides point to 'behind the thermostat', but as the boiler has a wireless thermostat, I'm guessing it's housing wires within it... somehow!

(Thanks)

Original Poster

So - I've had a couple of PMs since this thread asking about what happened. The Pro came, looked at the boiler, sniffed that it was incompatible then left and issued a refund. Undeterred, I spent 8 months researching different installers. A local guy just came and installed it for me - it took him over 2 hours, but I'm finally Nested up!

how did he manage to get to 12v wires and where are they located

I'm in the same dilemma, hooked up the next using a socket plug that comes with it but ideally want to hook it to the room thermostat that has 240v live wire, how did he get the 12v live wire

Please help, will really appreciate it, thanks in advance

Original Poster

I have no idea. He ended up wiring the old thermostat controller into the boiler system.
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