Does leaving ceiling fans on improve A/C effeciency?

Question

Let me start with saying I know ceiling fans don't cool the air. My question though, is do ceiling fans help circulate the cool air from the handler in such a way that it would trigger the thermostat to less frequently turn the system on?

When we leave the house, we have the thermostat set on about 80. We live in Florida though, so the house has no issues hitting 80 and staying there basically 24 hours if we allow it; point being, the air is going to kick on throughout the day, regardless. I'm curious if ceiling fans will help it to kick on less frequently.

I guess the best option would be to set the thermostat at 82 instead of 80. But even then the question remains, do ceiling fans help lessen the time the unit is actually on?

Answer 1

A fan won't improve efficiency, rather the opposite (more circulation means more loss to the outside).

But it might improve comfort. Increased comfort can result in the occupants raising the temperature, and thus reducing cost.

Answer 2

The only thing a fan would do is it might increase the circulation or distribution of conditioned air. Also because moving air causes evaporation it would feel cooler to the skin. Lets call it chill factor, you know the weather man uses it and heat index all of the time. So if it feels cooler, you can actually set your thermostat higher by a few degrees and still feel comfortable. That would allow less run time for the compressor and energy savings.

In case you're wondering if I am a believer, I have a fan in every room in my house except for the kitchen and bathrooms.

Answer 3

Efficiency of your A/C unit does not change - it is just as efficient with or with out the fan.

With the Fans - you are circulating your hot air - some people use reverse air flow to pull hot air down others use forward flow - cool air upward - the difference is in where the circulation path is and of course ceiling dust.

What happens is that more of your air is being cooled in the home - so it feels a little cooler all the way around. It improves the overall cooling of the home for this reason.

Your A/C runs just the same except overall temperature is more homogeneous and so you can get away with a slightly higher thermostat temperature setting (about 2 degrees).

EDIT 9-2-2017

Don't set your thermostats at 82 unless you are comfortable at 80 degrees. The amount of time to re-cool the house down to say 76 or 77 will cause your ac unit to run for HOURS.

As for Ceiling fans they will run continuously ..how many?? One ceiling fan is like leaving your Air Handler Fan on ALL the time! More than one - multiply that.. Ceiling fans may help in that all the air is roughly at the same temp ; however they use electric and if your bottom line is $$ - that will not solve the problem, it will only aid in comfort and also preserve the AC unit a little bit.

If it boils down to dollars - you might have one of those big box Digital Thermostats - meaning it is probably a honeywell - generally the swing is .5 degrees . Get Rid of that thing and get a better t-stat - I had one of those and I can't comment without bashing it.

I had lived in O-Town 1700 Sq Feet Vaulted Ceilings through out, no trees for shade, with an East facing back Plenty of Large Open Windows and large sliding door. I used a LUX digital Thermostat and set a 2 degree swing When out of town I left it at 79 or 80 Degrees depending; in town I managed leaving it at 77 degrees with a 2 degree swing setting. The thing worked like a charm; with 2 degree swing set your temp 1 degree cooler than your 'I am ok but just a tad cooler temp might be nice'. . Your body will not notice the difference. My electric if I can remember the Highest bill I ever had I think was $140 (exceptional reason for that) .. but it usually hovered in the $100-$110 range. That was from the poorest performing AC unit the builder could install - I remember the energy tag with that arrow slider thing ...'Your Unit Annual Costs $$$$$ , all others much BETTER' - Installed by the builder!