Nest Compatibility with my boiler?

chrestomanci

Hi,

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?

plbs76

Did you find a solution? Have the same Saunier Duval F 35e boiler and looking at a Nest.

chrestomanci

Nope. Sent it back as my 30-day returns period was close, but still trying to figure it out. My area doesn't have Nest Pro people I can call out, so I'm just relying on the Internet.

Nest themselves are useless - because the person they sent said 'no', they refuse to double check - even though he barely took off his jacket!

On a separate forum, someone told me it *would* be possible. I tweeted SD and they said the Nest should be compatible. Maybe your experience will be different. Please do update me if you try!

matelodave

I'm not an expert but I've wired a few boilers and built my own interface units and as far as I can see from the Saunier manual there's nowhere to wire in an external thermostat. The boiler has it's own wireless thermostat/controller which is dedicated to the boiler.

I'd agree with the fitter from Nest - the manual does not give sufficient information to grovel about inside the boiler to find any interface points and untutored poking can cause very expensive damage to the internal control board. IMO he made the correct decision

Unless Saunier can provide you with an external interface device or information which allows the connection of non-Saunier devices like controllers or thermostats then it looks like you cannot have a Nest or anything similar. Perhaps Saunier themselves have a remotely accessed controller similar to a Nest or Hive

Try speaking directly with Saunier or their distributors to see if anything can be done. You'd need a circuit diagram or actual details of the interface connections.

plbs76

Completed a Contact Form for both Saunier Duval and Vaillant (SD's owner) but never heard back. So phoned Vaillant who were pretty clueless. After waiting on hold for ages, the reply was "We don't do NEST so can't advise. But providing thermostat is 24v then that's ok".

The Heat Link (HL) is the unit that's directly wired to the boiler, whilst the Nest can either be plugged into the HL via USB or wirelessly talk to the HL (the latter option means it needs to plug into mains). Slightly confused as to if HL voltage converts down to 24v for boiler. And as matelodave says, not sure how you connect up anyway given the boiler has its own built in wireless interface.

Does the wiring diagram on page 31 of the F35e manual from the OP help anyone who can advise?

Had my boiler serviced a couple of weeks ago and engineer said it was possible. I'll go back to him and see if he can shed some light on this.