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A/C Thermostat electrical wiring question

G

good drown

does anyone in here understand electrical wiring for thermostats? i got a new thermostat for my house, a nice touchscreen digital unit, as the old one is from 1988. i take the cover off and the wires are not like the book says. it say a red green and yellow, and a white. it actually has 2 whites a red, and a black. this is a old mercury thermostat, and there is 2 mercury tubes, so there is a white wire that connect them. i imagine that one will not be needed, so its just the 2 whites, 1 black, 1 red. any ideas?
i can take pics if that helps.
the new one has lables for each of the 9 wire slots.
X C X W2 AUX
X G X Y2 E
X Y X L
X O/B W
X RC
X R



tHANKS!!!
 
C

CaliRaised

Member
red to R (usually has jumper on it for r1,r1, leave it there), white to C AUX, both red and white 24V wires control the fan circuit if wired properly. yellow to Y, controlls ac, in your case this themostat can also control a 2stage furnace therefore you would put it on Y2, green wire goes to G. Hope this works...
 
G

good drown

CORRECTION!!!
the wires i have from my wall are 2 whites, 2 blacks, 1 red.
i am guessing the 2 mercury tubes are for one for hot and one for cold.
i have a heat pump with backup.
each mercury tube gets 1 white and one black. there is a white wire that connects the 2 tubes.
the red cable goes to something that connects to the top mercury tube.
 
G

good drown

here is a picture
cant wait to get this thing up, 7 day programming. you can set 4 different temp changes a day!
picture.php
 
Smokerman

Smokerman

Well-known member
Veteran
You still have the sub base on the wall. Take that off, and see what wires are behind it.
 
G

good drown

Smokerman said:
You still have the sub base on the wall. Take that off, and see what wires are behind it.
Click to expand...
GENIUS!
its labeld, but there is still a few wires i wont know, here is what i see, ill get a pic up later on.
R-red wire
T-brown wire
O-orange wire
G-green wire
Y-yellow wire
X2-black wire
B-Blue wire
W-white wire

i get where everything goes except the brown
 
the Rock

the Rock

Active member
you didnt get any paperwork with the new stat ? sometimes they have wiring diagrams that cross reference the wires back to older stats
that looks like a pretty custom stat(subase) if it will work for coventional heating and also for a heat pump
what do you have X2 going to on new stat
some of the newer stats only use 6 wires or maybe thats for newer heat pumps(heat bpumps are pretty rare where Im located)
 
G

good drown

it says this for units with heatpump

RC gets RC or R(so thats red wire)
R gets nothing, as there is a jumper to connect this and the RC
O/B gets O, H, or B(so i assume O, the orange cable)
Y gets Y(yellow wire)
G gets G(green wire)
C gets B(the blue wire)
L gets L or F(not sure what to use)
E gets X2(x2 black wire)
Aux gets W(white wire)

so it only leaves brown to the L. i just dont want to blow anything up. i can either connect it, or ground it with tape
should i try it?
 
Smokerman

Smokerman

Well-known member
Veteran
Try to get a picture of the terminal strip on the air handler or furnace, what ever you have.
 
G

good drown

im not sure where to find that, i went outside to the a/c unit didnt see anything.
i figure its a 50 50 shot. either ground the T wire(brown wire) or wire it to the L.
im hoping somebody can shed some light to this
 
Smokerman

Smokerman

Well-known member
Veteran
As near as I can tell, Blue=C Red=R Green=G White=Aux Yellow=Y Black=E Orange=O/B Brown=L
 
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