Wiring Precautio

IIdentifying Thermostat Wires

(1)Meaning of thermostat wires:

You need to know the colours of some of the wires commonly used in
thermostats as well as their functions:
R(Red):Power Device-24VAC
RC(Red):Power from Cooling-24VAC
RH(Red):Power from Heat-24VAC
C(Black/Blue):Enables 24VAC Power (Common)
W(White):Primary Heat Call Relay
E(Brown):Emergency Heat Relay
AUX(White):Auxiliary heating
Y(Yellow):Primary Cool Call Relay
G(Green):Fan Relay
O (Orange):Change-Over Relay (Cooling)
B(Blue):Change-Over Relay (Heating)

(2)Determine whether it is a conventional system or a heat pump system:

Typically there are two sets of labels on the thermostat connector, one
for conventional HVAC systems. One for heat pump systems.
The wiring in the HVAC system consists of:R、RC、Y、C、W、G、Y2、W2
The wires in the heat pump system consist of:R、RC、Y、C、O/B、G、AUX/E、
L(The L wire can be used to power the indicator light on the old thermostat)
While it is possible for thermostats to have different wire colours, it
is sometimes possible to tell the type of system by the wire colour. For
example, thermostat connectors have O, B, O/B, and W markings: those with
orange wires usually indicate that you have a heat pump, and those with
white wires usually indicate a conventional system.
NOTE: Be aware that plugging wires into the wrong thermostat connector
during setup may result in system failure or damage.

II、Help with unlabelled wires:

If encountered there may be no connector label on the thermostat. Or the
label may have disappeared over time. You can use the colour of the wires
as a guide to compare the wires to the wiring on the system's control board
to find the meaning of the function to which the wires correspond.
NOTE: Most systems will not use all of the wires leading out of the wall,
do not connect these wires to your current thermostat without checking
the wire identification to prevent connecting wires that do not need to
be connected to the thermostat, to the thermostat.

III、Checking the system's control board:

1、Switch off the main power supply of the system at the breaker box
Turn off power to the system using the main switch on the breaker box.
This step is important for the safety of you and your home.
2、Test whether the power supply is off
If you can still feel the cold or hot air blowing out of the vents, or
if the furnace or fan light is on with the old light, then it means that
the main power has not been switched off, and you need to switch off the
main power before continuing.
3、 Remove the system panel
After the power has been successfully turned off, look for the removable
panel. It may have a handle or latch, or you may have to unscrew it. Be
careful not to touch any of the components inside the system. This is
because some HVAC units contain large capacitors, similar to batteries,
that store electricity.
4、Finding wire connectors and photographing wire wiring
After removing the panel, find the control board. It looks like a circuit
board and usually has a lot of wires attached to it. You should find several
sets of connectors on the control board with wires attached. You may see
connectors with R, W, G, Y, C, or O/B markings, and you will notice thatthe wires on the Philosophy System connectors are the same colour as the
wires connected to the thermostat, making it easier to handle the
unlabelled wires and do identification confirmation.
5、 Close the system panel
There are some systems that require the panel to be properly closed in
order to start. If the system does not start after the power is turned
back on, make sure the panel is closed and all latches are securely

IV、Understanding thermostat jumpers

In the connector of the thermostat, the two wires, RC and RH, are usually
connected together with a short wire (as shown in Fig. 1). Our thermostat
only supports the insertion of one wire in each connector, and it is only
necessary to connect the wires leading from inside the wall to the
thermostat to the corresponding terminals.




Picture: Jumper Wires

V、How do judgement B-line, C-line and regular line?

The wire labelled B should be plugged into the O/B connector of the
thermostat and serves to control the reversing valve of the heat pump,
switching between heating and cooling modes.
The C cord is the utility cord and should be plugged into the C connector
of the thermostat.
NOTE: If the utility cord is plugged into any connector other than C, it
may blow a fuse on the HVAC system and/or damage the thermostat.
Check for C connectors:
If the thermostat has a connector labelled C in addition to the B connector,the B and C wires are to be connected into the corresponding thermostat