what do the R C and W posts do? n260 c wire to relay

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wyreman

Senior Member
Location
SF CA USA
Occupation
electrical contractor
so I should know what the stat terminals do, actually i thought i did

i installed a 240v toe kick heater in our new bathroom
i source it from a cabinet w a 2p relay [24v coil]
Toe kick works great when you pick the coil closed

now i install the nest thermo stat
he starts to give me the n260 code
oh, he needs a common wire...

i only needed two wires to pick the coil before, but i added a 3rd wire for the common.
so now I have [lets call call ém tx1 & tx2]
switched tx1 at stat [in this case red] landed on the red post
steady tx1 at stat [in this case yellow] landed on the C post
steady tx2 at stat [in this case white] landed on the W post

I can pick the coil direct to the TX and the relay and the heater are fine.
Just too dim to see the smart switch in the stat :/ it no worky.

what do the R C and W posts do?
🥸
I thought
R was the switched hot which I have [TX1]
theres only R, not Rh and Rc

W was the return path for R [TX2]
and
Y is the steady version of the switched TX1 landed on the common post

thanks guys
 

hbiss

EC, Westchester, New York NEC: 2014
Location
Hawthorne, New York NEC: 2014
Occupation
EC
In addition, on a heating/cooling the thermostat there may be two R terminals, RH and RC to accommodate separate transformers in the heating and cooling systems. The "hot" from each transformer would go to the respective RH or RC with the commons together on C. If only one supply or transformer is used for both heating and cooling, you jumper RH and RC and connect them to the red lead.

-Hal
 

wyreman

Senior Member
Location
SF CA USA
Occupation
electrical contractor
I mean before I retired my answer would be
I’m a union electrician I work for the government and the HVAC guys just do a little bit of electrical wiring after the disconnect and I don’t do the HVAC because they are my brothers

but here I am retired I guess doesn’t matter anymore and I got called out here
Reportthere’s no power hvac said he doesn’t have it he’s running a three Legget dog

so I get here and I’m checking all the rooftop units and they all got three legs so thermostat is lit

and I call for heat andnothing
I go and I bump the contactors and they bump Just fine
It’s either a false report or I’m at the wrong address!

so long story short you’re right
It’s either a false report or I’m at the wrong address!so long story short you’re right



It’s either a false report or I’m at the wrong
Address

long story short you’re right
 

wyreman

Senior Member
Location
SF CA USA
Occupation
electrical contractor
You need to get acquainted with HVAC wiring.

View attachment 2558270
-Hal
So to your point with the control wiring
Of the low-voltage T1 and T2 you can basically jumper anything except the common wire
From RH or rc for a bump, for rotation

Can’t be more complicated than a hillavator
used to put them in a long time ago
 

wyreman

Senior Member
Location
SF CA USA
Occupation
electrical contractor
That’s not my job really here I just prove I got three phase power

so it’s a false diagnosis for HVAC or I’m at the wrong address
 

wyreman

Senior Member
Location
SF CA USA
Occupation
electrical contractor
You need to get acquainted with HVAC wiring.

View attachment 2558270
-Hal
printed thank you that was enlightening

the only thing about crawlspaces is while it is good for mobility, it is not so good for dignity

I remember the preacher saying, one thing in the story of the prodigal son, was at first that the father ran to see his son
But when he was yet a great way off, his father saw him, and had compassion, and ran,
because the father in those days was not going to be running, was not dignified

anyway, I ramble - just wanted to say thanks for taking the time to answer my question that was helpful
 
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