Honeywell CT3400 Programming And Installation Instructions page 8

and wrap them separately using electrical tape;
do not wrap them together . Place the wires
where they will not interfere with the operation of
the new thermostat. Record the colors and ter-
minal designation labels of the remaining wires.
Six or more wires?
If there are six or more wires (excluding clock
wires attached to terminals), you most likely
have a variation of a heat pump or multistage
system. The thermostat is not compatible with
such systems so return the product to the place
of purchase.
Three thermostat wires?
If you have three wires for heating only and can
operate the fan using the fan ON switch, this
thermostat will work with your system. However,
some hot water (zoned) heating systems have
three thermostat wires. The thermostat will not
work without installing an isolating relay on these
systems.
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