Tag Archives: rc840

map of nest thermostat location relative to gas heating system

16 Jan

Good evening to all,

I said in my previous post, since we have been talking a lot about wiring and electrical aspects…

at some point comes the “routing” of all those connections. Below you can see if my apartment and

the three key area of interest: the heating system location, the breakers box and last but not least my nest thermostat location.

A couple of comments:

  • all rooms are fitted with cast iron radiator
  • each cast iron radiator is fitted with a thermostatic head to the exception of the so-called “Bedroom 2” where the thermostat is located (for obvious reason)

the idea is to regulate the coldest room to whatever temperature I need and let all the other room (warmer in general) get settled via their individual thermostatic heads.

All I can say even before the Nest this setup worked pretty well – but the smartness of Nest is likely still to bring energy savings (hence dollars, Euros or whatever your currency is – I am flexible). the only issue I know with this setup, I will likely have is the auto-away feature not working well given the location of the thermostat (comments are welcome as usual).

nest thermostat appartment

Current plan:

– to wire my nest thermostat to the breaker box where the Aube RC840 unit will be located (this requires 3 wires, W/R/C)

– wire the aube RC840 to the Gas heater (this requires also 3 wires Ns/Ls/Lr).

Alternative plan:

– I may place my Aube RC840 right next to the gas heater (in case I struggle to add an extra wire – see my previous post)

– route W/R/C wires to the “breaker box” and then dispatch them to the nest location by means of proper “jumpers”

wiring nest thermostat aube rc840 heating system

I have full flexibility when it comes to the number of wires to be run from the green box (the breaker’s box)

to the Nest Thermostat, however, I am missing 1-wire from the green box (the breaker’s box) to the gas heating system (blue).

As a side comment, a Neutral/Line/Earth are also needed to supply the Gas heating system (hence the 6 wires needed)

talk to you guys soon, any feedback? questions? critics? candid feedback is always welcome!

missing 1 wire from my gas heater to my Aube RC840 to finish off Nest Thermostat wiring!!!

11 Jan

Dear all,

have verified in full my previously recommended wiring  earlier this week – having a 3-wire (220 240 Volts) cable running from my gas heater, to my RC840, and 3-wire from my RC840 to my nest thermostat.

While doing this, I have actually used this to let me Nest get fully charged, updated to the latest software, and exercised it a bit.

A few comments for those who go thru this process:

  1. it took a few hours to get my nest battery charged up to at least 3.7V
  2. note that in between it may (at least mine did) reboot a few times – realizing it does not have enough energy to run wifi (required to get the update done – have no idea about the size of the download by the way, do you?)
  3. 3.7V is critical as it is the minimum Nest needs to be able to launch software updates
  4. once update was done, an easy trouble-free process, I was able to fully control my nest via my Ipad

I live in an 1930s building, and our apartment got renovated to the current Electricity standard a few years ago (meaning I have a decent amount of extra wires running thru the various electricity access). Frustration rose when I realize I did NOT have a 220 240 Volts with 6-wires but 5-wires!

This means I can’t properly wire the Ns/Ls/Lr from my heating unit to the RC840T (I had planned to locate it near my fuse box – opposite from my heating unit).

So I have paused my installation – and – it looks like the only alternative is to change the heater supply cable and upgrade it to a 6-wires one.That’s assuming of course, I have room to retrofit it!! If you can think of anything else to do… please chime in now!!

In any case, I have updated and confirmed now that the diagram below is fully working.

nest thermostat 220v rc840

if you can’t figure out how is laid out the apartment and how the wiring has to run, I will draw up a schematic of the flat and the way the wire will be running thru.

buying a RC840T of Aube Tech via Smarthome’s website

6 Jan

Dear all,

I am going to briefly explain where did I purchase my five Aube’s Relay/Transformer RC840T .

in a previous post, I had mentioned the following:

#1 this product is not available in France and possibly not in Europe as it is not EC “stamped”

#2 Aube (North America) did categorically refuse to sell me a few units – probably for liabilities/warranties reasons.

I just want to make it clear I am not affiliated to Smarthome, but it turned out this is where I have placed my order for five units.

honestly, this turned out to be a smooth process (I even talked to their hotline at first), however it is worth pointing out that shipping costs were high – that’s also the reason why

I did  order five units instead of one as originally planned.

The RC840T acquired is located  here. I am under the impression those items are currently on sale as I post this message (!)

and I have recently posted feedback and rating which one should be able to read once they approve it.

for those of you interested, I am happy to share details of both shipping and taxes. I will post later…

the natural gas heater and its nest access

17 Dec

my heater is a basic elm leblanc acleis 23kw natural gas.
it works on 220 240 volts and is currently trigger by a 2-wire high voltage thermostat.

here is the front of the heater


with the cover removed


the Aube/ RC840 box will connect instead of the grey and black wires.
those are precisely hooked to Ls and Lr connectors.

it is worth noting that I will leverage from the Ns connector which on a high voltage 2 wire thermostat is not used.

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