Furnace fan blows immediately when heating, when it should warm up

[richardc]

I have a forced-air gas furnace for heat.  I connected the Nest thermostat to W1, G, C, and Rc. When I turn on the heat from the Nest, the fan starts immediately. My previous thermostat ignited the gas first, then turned on the fan about 30 seconds later.  I noticed that the Nest had "Electric" as the equipment energy source, and I changed it to "Gas," but the fan still comes on immediately.

How can I set up the Nest to delay running the fan until the furnace warms up? 

@Wellcraft19 put a good description of the warm-up process in this reply. I don't recall how I set up "should the fan activate when calling for heat," but I think it should  be "Don't activate."  How can I retroactively check and change that setting?

[richardc]

The Nest and furnace are playing nicely together now. When I tested the change to the "Gas" energy source by raising the thermostat temperature above room temperature, the fan turned on right away.  When the room temperature went below the thermostat setting, the furnace started the gas first, then turned on the fan later, as it always has. Case closed.

[Jeff]

Hey richardc,

I'm happy to see that you got this sorted out. Before I mark this as resolved, is there anything else you might need or any other questions you have?

Thanks,
Jeff

[Jeff]

Hi all,

As we got our resolution here, I'm going to mark this one as resolved in the next 24 hours. Thanks to all who helped and contributed. If anyone has any other needs, please feel free to let me know before the lock.

Thanks,
Jeff