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…

Electrical wiring of my previous 220 240 Volts (high voltage) thermostat to my gas heater

21 Dec

default wiring for high voltage thermostat

220v thermostat wiring dry switch

to all, above is a drawing of my previous configuration using a “2-wire” thermostat, high voltage that is 220 240 Volts, directly connected to my gas heater.

couple of key points:

#1 the thermostat had batteries internally used to trigger the “dry switch” (now on the drawing).

#2 upon “heat” command (ambiant temperature below target) the “dry  switch” basically closes the electrical path between Ls and Lr

#3 once Ls and Lr are connected together, this triggers the heater (gas + circulator)

#4 Ns connector is shown although not used in this configuration since thermostat operates from its own supply (internal batteries)

electrical schematic of nest thermostat with 220 240 volts heating system

19 Dec

nest thermostat 220v europe

nest thermostat wired to a 220V heating system

following request for clarification,

here is my understanding of how this works, and particularly what is the RC840-240T doing for you.

#1 RC840T-240T is overkill – this box is designed to drive directly an electric heater (2kW or so…). this means the relay in this box can carry a lot of current

#2 note this device is not approved in Europe, probably because of 50Hz and 220 240 Volts (versus 60Hz and 110 Volts), so a new certification would be required.

#3 and I Will pause here, I have a doubt about the need (or not) for the C wire to be connected honestly, so I will investigate and report back once I have a chance to spend more time.

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.

received my 5x units of 220 240 Volts 24 Volts converter (with relay built-in)

17 Dec

I had initially the “ambition” to build my own transformer/relay in a box…
it turns out that both work and family activities forced me to look for a plug & play system.

I have ordered 5 units of this Aube RC840-240. Note those aren’t certified to operate in Europe… so you cannot supposedly buy them in Europe (have discussed with Aube themselves via emails and they refused selling me those).

So, I ended up buying those units from a 3rd party shop in California, they have arrived this last week end.

yesterday evening, at least to verify the concept would work, I plugged my current 2-wire “high voltage” thermostat thru this RC840-240 unit… and it works great. Picture and block diagram to come soon.

essentially, I am one step away from having my Nest wired to my heater a ELM Leblanc (natural gas) unit. Note the system I have actually selected could work as well on Electric heater systems with some cautious calculation.

Stay tuned.



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