jJim McLaughlin wrote:


red-white-yellow-green are actually rather standard.

red - power to thermostat
white - heat
yellow - air conditioning
green - air circulation fan

For example connecting red and white gives you heating.

blue - could be several things, like the other side of 24V if needed for
control power for electronics or clock.

Without looking it up, the Honeywell stat probably labels the terminals
with wire color - R, W, Y, G.

Any letters at the Trane t-stat connections? Or letters at the
furnace-end connections? Or as Jim said, look for a manual for the stat
or furnace.



The chances that any body reading on this goup has the exact
two thermostat models you are asking about in hand approaches
zero as an upper limit.

Assuming that the presently installed Trane worked correctly at some time,
get out your Trane manual for the Trane unit and find out from
the manual what the *function* of each of the terminals on the Trane
unit is or was. Write those down, e.g. Terminal 1 Blue = heat on,
Terminal 3 Yellow = AC on, etc.

Then look in the manual for your new Honeywell and find out what
functions go with what terminals in the Honeywell. Write those down.
Then match up the functions with the correct color wires.

Consider labeling each wire for its function befre disconnecing
the Trane, and keep those labels on each wire after connecting up
the Honeywell.

If you don't have a manual for Trane, google for their web site, find
a manual, download and print it out.



dancensound wrote:
I am tring to replace a Trane BAYSENS008B thermostat That has 5 wires as
follows Terminal #1 BLUE,Terminal#2 RED,Terminal#3 YELLOW, Terminal#4
Green, Terminal#5 White,with a HONEWELL RTH7500 on what terminals do
place
my existing wires on the new thermostat?