Honeywell RTHL3550 Owner's Manual page 7

Alternate Wiring (Heat Pump Only)
If labels do not match letters on the thermostat, check the chart below and
connect to terminal as shown here (see notes, below).
C
X
B
Leave metal jumper in place, connecting R and Rc terminals.
If your old thermostat had both V and VR wires, stop now and contact a
qualified contractor for help.
If your old thermostat had separate O and B wires, wrap the B wire in
electrical tape and do not connect.
If your old thermostat had Y1, W1 and W2 wires, stop now and contact a
qualified contractor for help.
If there were seperate wires on E and Aux, place both wires in the Aux/E
5
terminal.
4
5
L E AUX G
F X W
X2 W1
W2
Aux
L G
E
O
Y
F H
Y1
B M
O/B Y
7
R Rc
V R
VR
R Rc
2
MCR31275B