Tag Archives: 24v

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.

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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