Wiring question

[kddickey]

EMERSON White Rodgers1F56N-444 Snap-Action Thermostat

I am getting a Nest Learning Thermostat tomorrow...I've been doing some research to make sure I'm ready. Everything makes sense except that the old thermostat has a wire connected to an A terminal. I did some research and found that the A terminal controls the fan to turn it on before the heat cuts on. Can I just ignore that wire and have the nest control the fan? I've seen that question asked on some of the Nest installation videos that I've watched. Thanks for any help you can provide.

[jb76]

Hi - not sure of that furnace but Nest will expect to use the following for a forced air traditional furnace:
W1 - White (Controls Furnace)
G - Usually green (Used to control fan for unconditioned air)
C - Usually blue (Common) wire to provide 24 V power to Nest - critical to ensure Nest thermostat has at least 3.85 V to control equipment and be connected via wifi.
Y1 - Usually Yellow wire (controls AC/Compressor)

Rh - Usually red - Power from furnace
J

[Markjosephp]

Hello everyone,

Congratulations on your new Nest Learning Thermostat! It's a great addition for energy efficiency and convenience.

@kddickey, regarding the A terminal wire, it sounds like it's connected to control the fan to turn on before the heat cuts on. The Nest thermostat is designed to control both heating and cooling systems, but it's essential to ensure compatibility.

In your case, you can't simply ignore the A terminal wire, as it serves a specific function in controlling the fan. The Nest Thermostat has a G terminal for controlling the fan, so what you can do is connect the A wire to the G terminal during installation. This way, the thermostat can effectively control the fan as needed. But to be sure, please share with us a photo of your old thermostat's wiring setup and tell us what type of HVAC system you have.

Thanks for the input, @jb76.

Warm regards,
Mark