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HVAC Thermostat wire color code #186108 04/17/09 09:51 AM
Joined: Nov 2001
Posts: 75
B
Bill39 Offline OP
Member
I know the NEC doesn't do color codes but is there an accepted (traditional) color code for HVAC thermostat wiring?

+24V=
0V=
Heat=
Cool=
Fan=
Etc.=

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Re: HVAC Thermostat wire color code [Re: Bill39] #186109 04/17/09 10:10 AM
Joined: May 2005
Posts: 984
G
ghost307 Offline
Member
I don't know what it is, but every thermostat I've wired has little letters next to the screws for the black, yellow, green, red wires. If that's cast right into the plastic, it must be following some color code standard somewhere.


Ghost307
Re: HVAC Thermostat wire color code [Re: ghost307] #186110 04/17/09 10:37 AM
Joined: Jan 2005
Posts: 5,316
renosteinke Offline
Cat Servant
Member
Well, let's see ...
The red seems to always be the 'power in.'


Saturday - I've edited the daylights out of my post, because it was simply ... wrong.

Last edited by renosteinke; 04/18/09 09:55 PM.
Re: HVAC Thermostat wire color code [Re: renosteinke] #186112 04/17/09 12:16 PM
Joined: Oct 2006
Posts: 745
E
EV607797 Offline
Member
I've always seen:

24V common: Red
Heat: White
Cool: Yellow
Fan: Green
Blue: Second heat stage
Orange: LED for aux. heat
Brown: LED for emerg. heat


---Ed---

"But the guy at Home Depot said it would work."
Re: HVAC Thermostat wire color code [Re: Bill39] #186120 04/18/09 03:35 PM
Joined: Mar 2002
Posts: 7
K
klein man Offline
New Member
Here, Im an HVAC Controls Tech. This is a complete diagram for different systems. Ive added Gas, Electric furnaces and heat pumps. I can add water source HP's if desired.

(R) Red - Power
(W1) White- Heat
(W2) Blue- Second Stage Heat
(Y1) Yellow First State Compressor
(Y2) Jumpered (Board Controls Second Stage Compressor)
(O) Orange- Reversing Valve (Heat Pump Only)
(B or X) Depeneding on Manufacture will be Common (Heat Pump Only)
(Brown and Pink) Outdoor Stat (Heat Pump Only)
(G) Green - Blower Relay

Aux Heat for heat pumps no longer is hooked up, the fuel master does it for the unit.

I could add a lot more, but start with these


Last edited by klein man; 04/18/09 03:40 PM.

Crozz
Re: HVAC Thermostat wire color code [Re: klein man] #186137 04/21/09 01:03 PM
Joined: Mar 2005
Posts: 1,213
S
SteveFehr Offline
Member
As klein man pointed out, there's common practice but no real standard so it unfortunately varies from brand to brand. Google is your friend, and will answer your questions for your particular unit smile


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