My tendency would be for the fan to only run while the AC is on, but there is an option for continuous fan operation. Is there more to this function than I realize? Or does it just waste electricity?

Mine has a circulation mode as well where it runs about 1/3 of the time... I keep it on that setting cause I don't like stale air.

It might not do anything but a blower motor doesn't use all that much power anyway.

I’ve wondered about this myself. I’m interested in the responses.

Straight up on a standard system it is a waste of electricity. A variable speed blower should keep the house more evenly as they run at lower speed for longer helping to keep the air circulating.

I have the switch ON in hotels for white noise. At home...AUTO. But I do run 2 ceiling fans the entire time I'm in the house...

^^^ Good point about ceiling fans. I keep two going too. I prefer not to have the breeze in the bedroom though.

FWIW, I have mine set to auto and not constant run at this time.

Still interested in other's thoughts.

I use circulate as it keeps the temperature more even in my 3 story townhome. When circulate comes on the fan runs at a lower speed. I also use manual on my thermostat as it is easier to adjust.

If your relative humidity is high enough that your evaporator coils are condensing water then you definitely do not want your fan to run all the time because it’ll just recirculate that moisture back into your duct work and the rest of your house when your compressor isn’t running.

I’ve thought about using it at night when outside temps do not make the AC run much. The bedroom can warm up a bit with two people and a dog while the rest of the house is cooler. We do have a circulate mode but it doesn’t move as much air. Our unit has a variable DC motor I think.

At the risk of getting blasted by other HVAC pros here, the HVAC guy who installed my Lennox AC in 2018 advised me to have it set to “on” and not “auto” when I’m running it 24/7 like I do here in PA from June to September

Awhile back, had to get a new AC. Told the AC guy what I needed temperature-wise from a new unit here in Las Vegas, NV, with it's extremely low humidity and extremely hot summer heat 24/7. Was told it would work for the size place I have. Nope; it kept freezing up at the max heat of the day. Was told it needed greater airflow than my old unit. Put the fan on manual so it runs all the time; that combined with a large attic fan going 24/7 to blow heat out, and no more freezing up and the temp stays where I want it.

quote:

Originally posted by thumperfbc:
Mine has a circulation mode as well where it runs about 1/3 of the time... I keep it on that setting cause I don't like stale air.

It might not do anything but a blower motor doesn't use all that much power anyway.

Same here, on new system installed in April. I also use the Circ mode, but do not draw in fresh outside air.

Running the fan at my house raised the humidity like crazy. If the fan isn’t allowed to shut off when the compressor stops, the air moving across the wet A coil sucks up the moisture before it has a chance to drain out the condensate line and dumps it back into the house.

I put mine on continuous and have for 20 summers. 160 year old house with a 30 year old system that utilizes much of the old ductwork.

About the only way to keep the upstairs reasonably cool is to keep moving the cool air back upstairs.

I run two ceiling fans and the a/c is on Auto (fan runs when it’s cooling) it’s set to 74° all the time until fall when it’s not 100° or more here in central Texas

Like erj_pilot, when I’m in a hotel I put the fan on ON, to make noise-as the cycling awakens me.

quote:

Originally posted by Largefarva:
If your relative humidity is high enough that your evaporator coils are condensing water then you definitely do not want your fan to run all the time because it’ll just recirculate that moisture back into your duct work and the rest of your house when your compressor isn’t running.

^^THIS^^
You are just returning moisture back into your house that should be draining outside!
Use other fans to move air and NOT the “On” setting for the AC.

Pros for running the fan continuously:
Space temperature tends to be more even
Air is being filtered.

Cons:

more energy
Moisture carry-over on off cycle ( IMHO minimal, engineering improvements as in sloped pans has improved the issue )
Note: Possible issue with negative space pressure from leaking duct work, compounding space humidity.
If you observe that your humidity increases with the fan on continuously, you may have a negative pressure issue pulling in the humidity from outside.

Keeping it on helps even the temps in the rooms without the thermostat.

If you are running the fan continuously, the vents and the dampers are not balanced correctly. I spend a ton of time balancing all the vents and rooms when I move into a home. I’m not talking about opening or closing down the register, but the dampers that are put on each trunk at the octopus in the attic.

Once the rooms are balanced the circulate mode should be more than plenty.