Tag Archives: wiring

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.

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)

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