Venstar T7900 - Manual (Page 78)

70
Installation Instructions
Remove and Replace the old thermostat
To install the thermostat properly, please follow these step by step
instructions. If you are unsure about any of these steps, call a qualified
technician for assistance.
•
Assemble tools: Flat blade screwdriver, wire cutters and wire
strippers.
•
Make sure your Heater/Air Conditioner is working properly
before beginning installation of the thermostat.
•
Carefully unpack the thermostat. Save the screws, any brackets,
and instructions.
•
Turn off the power to the Heating/Air Conditioning system at
the main fuse panel. Most residential systems have a separate
breaker for disconnecting power to the furnace.
•
Remove the cover of the old thermostat. If it does not come off
easily, check for screws.
•
Loosen the screws holding the thermostat base or subbase to
the wall and lift away.
•
Disconnect the wires from the old thermostat. Tape the ends of
the wires as you disconnect them, and mark them with the letter
of the terminal for easy reconnection to the new thermostat.
Additionally, we recommend taking a photo with your phone of
the connections for future reference.
•
Keep the old thermostat for reference purposes, until your new
thermostat is functioning properly.