If you’re going to have an attic fan installed, you’ll need a thermostat switch fitted to it. An attic fan can be a great addition to a home and removes much of the humid air in summer. It can even stop items that you store in your attic from becoming moldy. Intalling a thermostat switch is not a difficult job and you don’t need any special skills in order to accomplish it. Expect the work to take about an hour or so if you’re experienced in working with electricity.
Step 1 - Secure the Switch
Start by screwing the thermostat switch to the plywood frame that houses the fan. Place it so it’s facing in the direction of the air that’s being drawn out of the attic by the fan. Remove the cover of the thermostat to expose the black and white wires as well as the green ground screw.
Keep the thermostat cover off to one side as you’ll be needing it to finish the installation.
Step 2 - Power
It is essential that power is supplied to the thermostat. The simplest way to acheive this woulld be to run the power from a light fixture in the attic. Attach NM cable to the wires from the thermostat with wire connectors, screwing the ground firmly into the ground screw cavity. Staple the wire along the wooden beams at 12 inch intervals, hammering the staples in with the hammer for a frm hold. Leave ample wire near the light fixture so you can attach it more easily later in the task.
Turn off the breaker for the attic light. Allow the bulb to cool completely before proceeding. Turn on your flashlight and have the beam trained on the junction box for the light. Remove the bulb and the fixture so you have clear access to the junction box. There should be a knockout section on the junction box so remove it with a hammer and screwdriver before feeding the cable through.
You should have ample wire on the cord to work with. Strip the ends of the wires and attach the end of the black wire to the black wire, the white to the white and the ground wire to the ground wire. Cover each connection with electrical tape so no bare wire shows through. You can also use electrical connector block for this particular stage.
Replace the fixture and the bulb, screwing it firmly into place. Now, turn the breaker and the attic light back on. This will send current to the thermostat switch.
Step 3 - Temperature
You now need to set the temperature for the attic fan thermostat switch. To do this, screw the thermostat cover in place and use your screwdriver to set the temperature at 105 degrees. This is when the attic fan will kick in and start removing the hot air.
With the wiring in place, the thermostat switch should work automatically. Check later to see make sure the fan and thermostat are still working properly and kicking in at the proper temperature.