3
HOW TO USE THIS GUIDE
Before you disconnect the wires and remove your
existing thermostat, be sure this new thermostat, see the
CT70 wiring hookup diagram, will replace it and that you
understand how you will reconnect the wiring. To do that,
proceed as follows:

Step 1

Find the manufacturer of your heat pump in the Table of
Contents, and turn to the appropriate page.

Step 2

Expose the wiring on your existing thermostat (the
subbase) and check that the terminals on your existing
thermostat coincide with the terminals shown in the
second column (Existing thermostat wiring).
If they do, read and follow the installation instructions
provided with the thermostat.
If they do not, call Honeywell Customer Assistance toll
free at 1-800-468-1502, Monday-Friday, 7:00 a.m. - 5:30
p.m. Central time, to be sure you can safely use this
thermostat to control your heat pump.
Before you call, please have the following information
available: thermostat model number and date code, heat
pump model number and manufacturer, and number of
wires connected to the thermostat. The date code is
usually stamped on the back of the thermostat and is a
four-digit number; for example, 9346.