Latest Discussions : Electrical & Lighting


04:21AM | 02/01/05
Member Since: 01/31/05
2 lifetime posts

I am trying to install a new programmable thermostat (to replace the builder-installed one) in a brand new home. The existing thermostat has five wires connected to it. I marked the wires and their connections for the existing thermostat as follows.

White -> W

Green -> G

Red -> R

Black -> C

Orange -> Y

The new programmable thermostat has the following connections - Y, B, O, W, G, RC, RH. The thermostat says it is suited to five wire systems but I am not sure where to connect the wires since the letters don't correspond.

Can someone please help?

Thank you,



02:12PM | 02/06/05
Member Since: 03/20/04
24 lifetime posts
Ok, let's start with the obvious.

Below are the standard wire colors. Your installer may have used different colors.

white = Call for heat.

yellow = Call for cooling.

green = Call for supply fan.

red = 24V Power

blue = 24V Common

It looks like you have orange instead of yellow and black instead of blue.

On your new thermostat you may not need the 24V Common if the thermostat is battery powered.

Y = yellow (orange for you)

G = green

W =white

RC = red (cooling)

RH = red (heating)

The red should connect to both RC and RH (there may already be a jumper between them.

Tape up you black (24V Common) wire and try the thermostat.



02:51AM | 02/07/05
Member Since: 01/31/05
2 lifetime posts
Thank you Homer.

That's done it. Everything seems to be working now.


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