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Craig Muccio

About "Ask the Energy Expert"

Craig Muccio runs FPL's Conservation Research & Development Program and crunches the numbers to figure out how you can save by managing your energy use.

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A/C fan switch – “on” or “auto”? Which saves the most money?

By Craig Muccio

Asked on: August 28, 2014 by Beverly H., Weston

Which A/C fan setting costs more, “on” or “auto?” My friend believes the “auto” setting uses more electricity.

That’s actually a common, but important question. The on/auto fan switch on your A/C thermostat will affect the price you pay to cool your home. The A/C fan circulates the cooled or heated air throughout your home. Setting the fan switch to “on” will make the A/C fan run continuously, 24 hours a day. Choosing the “auto” setting will cause the fan to shut off with the rest of the cooling system as soon as your desired temperature on your thermostat is reached.

Fan “on” costs more
Advice from friends can be helpful, but in this case your friend was mistaken to think that the auto setting used more electricity. Let’s assume your air conditioner normally cycles off 30 percent of the time. In this example, turning the fan switch to “on” will make the fan run over 200 extra hours a month. For a typical size central air conditioner, that would cost you about $8 more each month. Keep in mind, a fan that runs all the time may also wear out sooner.

Another reason to keep it on “auto”
Setting your A/C fan to auto also helps provide better dehumidification. Have you noticed how moisture from the air condenses on the outside of a cold drink on a humid day? Your A/C unit captures moisture the same way, helping your home feel more comfortable. When the fan cycles off using the auto mode, moisture has a chance to drip from the cold cooling coils into the condensation pan and then drain outside. However, when the fan runs all the time in the “on” setting, less moisture has a chance to drip and drain outside. Instead, some gets blown back into the air again.

Some people prefer the feel or sound of the fan running all the time. If that’s you, at least now you know how much that choice will cost you.

Learn how to save even more
During Florida’s hottest months, we want to remind you that you can save five percent on your monthly cooling costs for each degree you turn your thermostat up. Also, our top summer tips can help you save even more.

You can also take our Online Home Energy Survey to get a personalized savings plan filled with energy-saving tips and recommendations. It’s easy, and can save you up to $250 a year.

Did you find this Ask the Expert column helpful? Get more expert energy saving advice by following our Ask the Expert column monthly and remember you can submit your own question.

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Comments [212]

  1. Mike Roberts

    When my fan is set to the on position it only runs at 10% of normal speed when compressor isn't running, this keeps air moving through the electrostatic filter keeping the filter working longer, cleaner air! My thermostat has a humidistat and when humidity goes above the preset point the compressor comes on and fan runs at half speed to reduce the humidity quickly. Cleaner air, controlled low humidity, makes it more comfortable the at a higher thermostat setting. It is a programmable unit to raise the temp when no one is home, while continuing to control humidity.

  2. brland1020#gmail.com

    Is it economical to leave ceiling fans on a low speed when leaving the house for weeks at a time?

  3. Winston Ebanks

    In the summer what is the best setting for my AC

  4. Elia

    At work, we have the A/C on "auto", but the office is still extremely humid. What else can we do?

  5. Maryanne

    I have pushed up the thermostat from 78 degrees to 80 degrees and my bill is higher this month. In fact it is almost $80 this month. . Yes, I know it takes time but why so long?

  6. Maribel

    Is it better to turn off your ac when you are leaving the house. And if so, if you are leaving the house for up to how many hours?

  7. SanDee

    I own a pied-à-terre (home away from home) in Miami and get a chance to stay there only 3-4 times per year. What temperature setting do you recommend I should leave the A/C?

  8. Bob Kreppel

    we live out of state and visit 4-5 times a year....when not there, what should we put the thermostat at??

  9. shannon

    Fpl says it cost 5 to 7.00 per month per ceiling fan also, so i shut off 6 i have for a month and a week, and my bill went still higher and one teenager was out of town, so i think they bill whatever they want sometimes!

  10. Jerry L. James

    I was told by the company that installed our heating/AC system in Dayton, OH, that lettting our low-speed fan run continuously to provide constant air flow was more economical and easier on fan wear and tear than having the system cycle continually all the way on and off. Are you arguing that point, or did you fail to consider a low-speed fan?

  11. john perez

    very helpful and informative.

  12. Rebecca Erickson

    I am sure that a couple of months ago I read on this FPL site that it was more efficient to run the fan on the AC all the time because it kept the air moving and while the fan was drawing electricity the compressor ran less often. At that time, I put my fan on run rather than auto and the house feels so much more comfortable all the time--not having "warm and cool" spells. Did I imagine I read that on your site? I am sure I didn't make it up but now you say fan on auto for efficiency. Please advise.

  13. Nancy

    You say turn off the fan when you leave the room. How long do I need to be gone from the room for it to be good to turn off the fan? What about when the a/c is on? I always thought ceiling fans were good to have on to keep the cool air circulating.

  14. chris

    what about the the hot air transferred from the attic thru the duct work? fan switch ( on ) poss.

  15. Todd Robinson

    On the first point, you neglect to take into account the possible shift in cycle time from leaving the fan going. This would depend on placement of the thermostat and if you experience hot spotting to any degree. Its quite possible the constant fan keeps the air mixing and therefore a slower overall temperature shift during the 'off' cycle of the compressor which draws far more power than the fan does. It may only take a 5% shift in additional 'off' cycle time to pay for the additional 'on' fan time. Unfortunately you can only calculate what the break even point will be, but each home would have to be evalutated for the functional effect of this. Could be + could be -. On the second point, air moving across the coils is what makes water condense on therm. When the fan cycles off there is no more air going across the coils to pull condensate from, so no more dehumidification. Also, when the fan goes off, so does the compressor and therefore the coils no longer stay cold (Ok, maybe for a minute), so again, no more condensate and no more dehumidification. So, the only reasons for keeping the fan on are that you either like it, or it helps keep hot spots from getting hot so fast (with possible extended 'off' time on the compressor). In the latter case a ceiling fan may be more efficient.

  16. Mariela

    What is the best formula to have less humidity and more cool in my apartment? I have tried auto/20 mts and auto/40 mts for the A/C fan but even though the temperature seems to be fine, during the nights it gets extremely hot. I think it is because of the humidity that raises during the night time.

  17. Merwyn P. Reaves

    Thanks for the comments on the ON vs AUTO fan settings. The comment about the humidy was a very good point that was news to me! Thanks

  18. John

    I think this misses the point of keeping the fan going. Obviously it increases energy use by keeping the fan on all of the time. The question is, will the home be just as comfortable with the temperature set to a higher temperature due to having the fan always running and if so, can the temp be raised enough to offset the cost of running the fan?

  19. RICHARD

    WHAT ABOUT THE NEWER AC SYSTEMS WHICH HAVE VARIABLE SPEED FAN MOTORS AND CAN BE SET TO CIRCULATE AIR OCCASIONALLY AT A SLOWER SPEED - WILL THEY INCREASE OR DECREASE ELECTRICAL CONSUMPTION?

  20. v allum

    At what speed should I set my ceiling fan in a bedroom that faces west and is very hot even when I set the thermostat at 74%?

  21. freda

    should celing fans be left on all the time to save energy? Live in south fl. and when away leave temp on 80.

  22. DEBRA PARKES

    I do have a question regarding slow cookers. how do they compare with microwaves,stovetops, & ovens? does it matter if you run on high r low settings? I use all of the above but would use the cheapest means first as long as it doesn't effect my cooking. The bbq is a great alternative.

  23. Lynda Barosi

    My husband puts the air on 81 - 82 when we leave the house, and when we return he turns it 78. This is our first full year living in FL, our neighbor said your conditioner will run more to cool it back down, plus you will get mildew or possibly mold. Is this true. She said, leaving your temp at a constant temp of 79 would save money and no mildew.

  24. Nick

    Your analogy is fine for peak or close to peak cooling conditions but does not necessarily apply for fall and winter months or even for overnight conditions. Also, my experience has been that the worst situation for motors is stop /start activity.

  25. joseph j bruno

    if I put a fan in my attic will that help with any savings

  26. TINA

    My AC will not cool past 80 degrees in my home. My landlord had a "ac guy" come and clean the coils and supposedly added refrigerant. And there are no leaks. While the system blows A LOT better, it still is not cooling. I called the "ac guy" again, and he said that he added a little more refrigerant and that there were still no leaks. Why add anything then? He stated that he told my landlord that a new unit was needed. I think he is just trying to get money out of him. The outside works great as does the inside. It is not blowing cold. Just cool. Any advice?

  27. veronica penate

    your comments are very helful we learn a lot.

  28. E McGurk

    I was advised to set the AC at a lower temp while away most of the time. This is costing me a great increase. What temp do you recommend so that mold does not form? The condo is rarely in use. Thanks.

  29. Michael

    But running the fan at all times will keep the house cooler when the compressor is off, hence the compressor will run less time. So there is a savings of electricity because it costs less to run the fan than to run the compressor. Also if running the fan reduces compressor use the compressor will last longer, and it will cost less to replace the fan motor than to replace the compressor. Am I correct?

  30. Carolann

    Two of my neighbors, who use their condos as vacation property, called frantically, stating that their must be something wrong in their condo as their FPL bill was sky high last month. Higher than when people are in the unit. They had me let the A/c repair in to both units. Nothing was wrong. Why was their bill so high if no one was using it and the a/c is running properly.

  31. Geoff Grant

    does leaving my thermostat at 74 degrees 24-7 & not changing it have a benifit to setting it lower at night when I want to be comfortable sleeping & higher when away during the day?? cost wise

  32. Patricia H

    Thanks so much for the information. Super stuff to know! -Patricia

  33. Clemencia Acosta

    Fan on or auto. This is an interesting topic however I am confused at my business we have a 15 ton unit and I was told that I must keep the thermostat set with the fan "on" as this will cool the units compressor and keep it from over heating. I was told that I must do this for commercial ac units to work properly to never use the "auto" setting. Is this correct?

  34. JJ

    What happens if you have a/c turned off & turn the fan on...will it act like an attic fan or is it bad for the unit?

  35. MARY SULLIVAN

    are overhead fans more reasonable to run than AC

  36. Edward Sotomayor

    Hi, My question is related to the amount of BTU that I will need for an apartment of 1000 SF. I have received a number of two tons for my apartament. However, my apartment does have catedratical celings throught the Apt excep in the two bathroom. The hight of the ceiling average about 13/14 foot to the lowest about 10. My apartment is also on the second floor which has concrete tiles and probably the lowest insulation used in the 1997. What will be the correct size of the A/C unit thta I should puerchase to replaced my old unit from 1997? Thank you very much for your feed back. Edward

  37. James Woods

    I appreciate knowing that setting fan on auto will improve dehumidification. Would the expert care to comment on difference between "fan on" and "fan auto" regarding 1. fan motor wear and tear 2. power usage.

  38. Ray Deien

    My daughter has been living with us for about 3 months. She believes leaving all the lights on the time is not costing me money. Can you please respond... she believes on running 15 lights throughout the house is normal. Not to mention every TV in the house. Please write me something I can show her to prove my point. She is very bright but doesn't believe she is truly costing me. I am on budget FPL. Last year this time my average FPL bill was $187 and now I am up to $225.00

  39. Wardo

    Does Florida Flicker and flash actually believe this is information is useful?. Duh, If I leave a motor and compressor run 24hrs a day or let it run 6-8 hrs a day like mine at 73 degrees. Or burn up the system like F,peel And low would like to run up your bill. Currently mine is 120 a month in August

  40. Randy Shipley

    Does having a dark roof result in a higher energy bill than having a white or light-colored roof?

  41. Richard Minster

    What if my air conditioning never reaches temperature I set it at? Richard

  42. Leo Oas

    Is it cost effective to replace my humidistat and thermostat with a programmable unit to control temperature and humidity. I have been setting the humidistat at the away setting of 60%, and the temperature at 80 degrees. We are snowbirds and are in Florida from Thanksgiving to the middle of April.

  43. C. Dupree

    I do both. When the Unit reaches the desired temp. The fan will cut off. The coil is still cold and so is the air in the duct work. I have metal duct wrapped with insulation. I think that I can still use the cold in the unit and the duct. The unit is in the hall in a vertical position. Cold air is heavier so it begins to fall back down through the unit. The thermostat is in the hall near the unit. I think it keeps the thermostat artificially cooler longer so the rest of the house doesn't get cooled off when it drops below the desired temp.

  44. Ernesto

    how much does it cost for an FPL technician to inspect my home for A/C leaks around windows and doors? How about to check for possible leaks in air ducts in ceiling space?

  45. Paul Cannefax

    I heard... I believe for your chat line "THAT" you should have your thermostat turn on your AC 2 hours before you get to 72 then once up have it raise to 78-80 T / F ?

  46. sandra musser

    Is it cheaper to close the ac vents in unused bedrooms or leave them open? Thanks

  47. RICHARD BALLENGER JR

    VERY HELPFUL.

  48. Rob

    I DISAGREE WITH YOUR ANSWER REGARDING CLOSING AIR VENTS TO UNUSED ROOMS. PLEASE SEND ME THE ARTICLE.

  49. Kadir

    Thanks for this explanation. However, I do have a question about this: Did you take into account the fact that the fan running may keep the house cooler a little longer and therefore allowing for the AC unit not to 'turn on' as often? Would that be possible? Thank you

  50. Katherine Callahan

    How often should the air filter be changed? We are snowbirds and are not in Florida except Jan. thru April. While we're away - we set the A/C up high, but we are not there to change filter.

  51. Robert Golden

    Being and air control eng I whole agree with you on the part of the RH factor .But I do run it on fan when we have extra people in our home but 75% of the time it's left on Auto.I am sure the most did not know about the moisture point.

  52. Kenneth Streisand

    BUT - running the fan continuously will keep the temperature in the house more uniform. And if the home is two stories, where the thermostat is on the upper level which is usually warmer, the AC will be switched on while the people downstairs will be uncomfortable cold.

  53. Barbara Kessler

    What temperature should I set the ac at if I am away from the house for a few weeks?

  54. Michael Del Sordo

    I am a new resident of Florida and I had my condo renovated. The contractor replaced my thermostat with a digital. There was also a dehumidifier thermostat that he removed when he replaced with the new digital thermostat. My question is should the humidistat been replaced or is ok with the new AC thermostat? He said it was ok, that I didn't need it with the replacement. Please advise.

  55. Jean

    My dad, who worked in heating and air conditioning, always taped the fan switch in the "on" position in our house. He said that starting and stopping was harder on the motor than the continuous "on."

  56. Bernie

    What on your thoughts on humidistats

  57. Nicola

    Thank you for sharing this information. I had it wrong.

  58. tom

    I believe that the start up of motors like engines in cars is actually when most oh the wear and tear takes place and that keeping a motor turning requires a small fraction of the power as compared to the start up. Has your conclusion actually been field tested in Florida, including the fan life?

  59. Alan DeVincentis

    Interesting take, but I would add that the 8.00 monthly to run the fan is a small amount compared to the cost of circulating air that should be left static after being cooled. If you are constantly circulating that product, it is picking up the heat from the ceiling, walls, and even the floor, and causing your system to cycle even more often than it would if allowed to stop. Then, multiply the smallest duct leak by about about 2.1 times, if you cycle on at 30%, and you are just cooling the outside air. And also the smallest duct leak puts your house under a negative draft, causing much more intrusion than had it just been static.

  60. MADAME Homes

    Live in a one bedroom apartment and have a central air unit that constantly goes on and off. Bedroom is hot while living room is cold unit is constantly "clicking" and switching off. My bill is increasingly higher. What setting or environmental tools, ideas, can assist me in decreasing my costs and increasing efficiency. Thank you in advance.

  61. John Forte

    Read your column about continuous air conditioner "on" use. What about air conditioner in the temperature "HOLD" setting?

  62. Don Sylvester

    I enjoy your advice very much. I especially studied your article on how to control humidity when away from your home for an extended period. I do have one comment on your current article. I believe that in some cases you might be able to feel as comfortable in your home by leaving the fan on continuously if it allows you to turn the temperature up a degree or two. This is because it keeps the air circulating during the period of time that the compressor is not running. What do you think?

  63. Sol steadman

    Would a renai type hotwater heater be less expensive then a gas water heater?

  64. V

    thanks for the tips, now I have a question...what if you turn your A/C up while you are out for the day and perhaps leave a fan on in one room - what is the relative use of a ceiling fan? Thanks!

  65. Michael Radd

    To further the A/C fan on/auto discussion, let's include paddle fans. A home with 2000 square feet of living space. Three bedrooms, family room, living room with paddle fans operating 24/7. Five paddle fans total. Which scenario is more efficient and cost effective. 1 - leave the A/C fan in the auto position and allow the paddle fans to operate. 2 - Do not install or if installed do not use the paddles fans and circulate the air with the A/C fan in the on position.

  66. ronnie baker

    very useful info.

  67. Russ Radcliffe

    I understand your numbers if I only have one fan speed,high, but what are the numbers when I have three fan speeds available, [low, med, high] and I only use the low speed?

  68. R Foutz

    For folk with 2nd homes in FL. Pls note this is a Fl answer. The condensation problem does not exist in VA. For FL U R correct. When our FL hs is vacant, we leave therm on 90% with fan on to circulate air to avoid mold etc. It has worked fine since 2006. Up "North" we do not run the fan in winter, only summer.

  69. David Good

    I have an air conditioner that switches to DC power when ON after conditioner shuts off moving air through the house and filter. The electric filter stays off but moves a nice flow through the house.

  70. FORTUNA BABANI MENDEZ

    I HEARD THAT FPL HELPS INSTALL INSULATION IN THE ATTIC TO CONSERVE ENERGY. HOW CAN I FIND OUT INFORMATION ABOUT THIS?

  71. Robert S

    I believe the answer is partly correct. The way I use the fan setting is to personally monitor the climate of my home while I am there. in my house I have a basement and there is a lot of cool dry air down there. when I turn on the fan for a couple of hours it recirculates all the air in the house and keeps it cooler and somewhat dryer without running the compressor. It is not wise to leave the fan running 24/7 you will be using more electricity and potentially shortening the life of the fan bearings and motor.

  72. bob

    I have heard it said that keeping a fluorescent light on for several hours is less expensive than turning it off and then on several times. Is this true?

  73. Diana

    All I know is FPL is outrageously expensive, no matter how you try to save. A total monopoly considering it hasn't any competition from surrounding states. Up in NH my bills were so reasonable compared to the Sunshine state. Rather go with a little less sunshine and way lower bills!

  74. august bucci

    Question: I leave my thermostat on 80 when we leave the house. My wife says the savings get wiped out when we return and the AC has to "work" harder to get back to 77 degrees where we usually keep it. I think we save by not having it maintain 77 while we are not home. Who is right?

  75. Yvon marcil

    Just to Know more about humidistat. Did they réduce à lot electricity Bill ? At what pourcentage? Yvon

  76. Robert Riegel

    We are snowbirds and our A/C guy told us to leave our dehumidifier off when we are in residence. Why?

  77. Kay Moore

    This question and its obvious answer are so very basic that is impossible to think someone would have asked it. Running a fan non-stop, 24 hours a day, when it is not needed, is absurd. Just think about it!!!!!!!!!

  78. Ron Gelb

    Don't waste your money. Warm water is free in South Florida (particularly during the summer months) why pay for it? Unless there is a specific need for hot water keep those single lever or knob faucets at the "Cold" position most of the time. Any other position infuses cold water into the hot water heater causing the heater to turn on. This wastes electricity because by the time hot water travels to the spout the faucet is usually turned off anyway.

  79. sara glenn

    my husband closes the air condition around 8:00am when I leave for work, he then turns it on around 4:00pm just before I get home. He thinks it saves electricity, however I do not agree because the house get so hot and it takes a long time to cool the house, which means the air condition keeps working a long period before it rests. I suggested to keep the air on 80-82 all day, and when I come home to lower it to 78. which way is the best one?

  80. Ray Karosas

    Helpful article.

  81. Edward Miller

    Your answer is a good one, but you have neglected to talk about the refrigerant cooling cycle. The compressor uses much more electricity than the evap fan. When the unit shuts down the evap coils retain coolant within and this is wasted as the tstat reaches temperature. With the fan on not auto the remaining cold refrigerant that has already been produced by the compressor in the evap coil is then ot wasted causing the extra cooling to be produced by the fan only. This can be a considerable savings.

  82. Howard Laucella

    Leave that fan on. Fan starting and shutting off wears the fan out. For me the difference of 10 years compared to using auto just 4 years fan life.Fan off fan on wears the unit.

  83. jenny

    Hi, I am always freezing that's why I just turn on my AC "on" late at night when I am going to sleep. So, the AC runs for about 10 hours at day. Because I don't like the sound of the unit going on and off about every 10 minutes I put it on "on" instead of "auto". Will this make my bill higher? Thanks!!

  84. Jennie

    Hi, my question is does this apply for window units as well? I live in a small apartment, one unit in bedroom and one in living area...I was also wondering why, if I have had the same routine of electric usage does my bill continue to increase each month since I moved in and is that just normal? Thank you..

  85. martin a koliner

    what is this less energy ceiling fans or air conditioning?

  86. Carolyn Fischer

    Shade trees around your home lower the cost of AC. We have 2 houses, one with shade, the other in the direct sun all around. The difference in cost is $100 in season.

  87. Derek Fitton

    We are not in our condo from April to October, I set my A/C thermostat to 76, and the humidistat to around 55%, I was told that if the humidistat senses high moisture, it will kick the A/C in, and the thermostat may go down to 72 or what ever it needs to be based on the humidity. Are these settings okay / correct. Thanks for your help and insight.

  88. Wade Kane

    Would from a home well spraying the external coils of a window unit make it cheaper to operate?

  89. Dean Loring

    So, what if the circulation in an apartment is very poor, even after FPL vent cleaning. My living room and kitchen get most of the cooling. The main bedroom less but not bad and the 2nd br, my office that I spend a lot of time in, is a hot box with the hallway between a equilateral bubble, with the ac running. I have started using two tornado type fans to send cool air at the floor level down the hallway to be directed into that room. I could not imagine turning off the fan when I'm in there which is a lot.

  90. La Gallagher

    Does this Also Apply to 'WINDOW" A/c's ???????

  91. Roberta Rome

    People in my building are paying less per month on their bill than I am and they also have their A/C on 24/7. What is the reason for this?

  92. Patrick Carrington

    My understanding is that when the switch is on "on," the fan is running all the time, but not the compressor. So it draws less electricity, because it is just circulating the air in the house. When on "auto" the compressor and fan come on, and circulates cold air until the thermostat causes it to stop when it reaches the temperature set. Am I wrong?

  93. Steve price

    Good info!

  94. Stan Smeltzer

    Your answer makes sense to me. However, I have a Geo-Thermo system for Heating and AC. Since I don't have an outside drain pan or coils like a conventional system, everything works in the two 350 water wells that provides the heating or cooling pre-temperatures for my HAVAC system. I was told by the technician to leave the Air Handler run constantly so the Air Handler motor will last longer and help with filtering the air in the house. Can you check if this is true? Thanks!

  95. Rudy Yarbrough

    Your example may be true if you just leave the fan switch in the on position all of the time. But what we do is during the times when the house is cool, like early in the morning we run the fan in the on position because the temp is cool but there is no airflow. By running the fan only, the compressor does not have to cycle on as often and the house remains comfortable. Once the inside temp rises to the desired temp we change it to auto. At night we set it to auto because we use ceiling fans to keep us cool without having to lower the A/C temp so much. So to me there is good times and bad times to use the "On" position.

  96. Walter Kraslawsky

    "Auto" is not necessarily correct for multi-level homes, especially with a variable speed fan. When an AC on the lower level cycles off, keeping the fan "on" keeps an average temperature uniform on all levels. With "auto," if the fan cycles off, summer heat can build up on the top level without being recognized by the lower level thermostat. That can force the homeowner to waste money with a cooler thermostat setting not needed on the lower level just to ensure a consistent comfortable temperature on the upper level.

  97. Jean Carbonneau

    I would like to know, wat,s his the best way when i leave my condo in april untilnovember, i am a snow bird and in my condo i have a desumidificateur control and my A#C control. Some on told me to put the desumidificateur at 62 and the A#C at 75. Do you thing it,s the good way???? Thank you Jean Carbonneau

  98. Bryan

    A couple of months ago you had a suggestion not to close off vents and doors in rooms you were not using because it would increase you electric bill. Please be corrected. I followed your advice and my bill increased by around $100 in one month. Closing doors and vents in areas of the house where you are not using will cause a higher velocity of cool air to be gelicered to the open vents thus coolin the rooms faster and the a/c is running less.

  99. Ed Plaggemars

    I'am not in Fl. all summer, what is the best settings for me to set my temperature and my humidity ? Thank-You; Ed

  100. Bard

    Do digital thermostats save more energy than the older mercury ones? Also if a room is used only a few hours a day is it better to turn off the AC or just set the temperature higher for tha time?

  101. Jim Sutton

    In the early 70s, I was setting up a computer system for the Marine Corp, in Yuma MCAS. This discussion came up, Fan ON or Fan Auto. We ran an experiment, using a humidity recorder. As a result, I had empirical evidence of what you just explained in your article. With the Fan in the On position, the humidity bounced all over the map. With it in the Auto position, it was consistent. I witnessed it and never knew the reason. Now, I know. Thanks.

  102. Lloyd Johnson

    My A/C blower fan control has 4 settings, off/auto/man/cont. If "CONT" is selected the blower fan runs at a preset minimum speed(just fast enough to barely move air from the registers, the blower fan control is independent of the thermostat, the blower fan runs all the time) when the temperature in the plenum above the "A"coil is greater than 73 degrees. As the temperature above the plenum falls the speed of the blower fan proportionally increases until it reaches a max speed. I noticed a slight decrease in my utility bill and a big increase in the comfort factor in the house (More even temps and humidity). I also have to change the filter more often. This A/C unit was installed 10 years ago and this control was an option that came with a higher quality blower motor. Is there any advantage to a system like this?

  103. Eric Koskoff

    The answer assumes that the temperature setting remains the same. I often turn off the A/C or raise the temperature setting by several degrees but will run the fan continuously for periods of time. I have tracked my energy usage closely and often save $10 to $15 a month with this approach. Too bad the answer doesn't mention this option. Since compressors use significantly more current than fans this is not a bad choice for some users.

  104. Janice McBride

    I use the 'auto' setting all the time and never on 'fan'.. I also set the a/c temp higher when it is hot outside. Thank you for the tips you enlighten us with.

  105. Joseph Solomon

    You are correct that placing the fan in the ON mode will increase the energy cost and the fan maintenance. However, the ON mode also provides for better dehumidification and a more comfortable home. A properly sized coil does not allow water droplets from the coil to be blown back into the airstream nor would they cause the humidity to rise. The water droplets need to be evaporated to add to the humidity level

  106. Robert Watson

    However, you fail to note that the continuous airflow may allow a higher temp setting. Thus the compressor would work less. How about a comparison of compressor usage cost vs fan.? Isn't same principle why using a ceiling fan in one room w/AC on auto saves?

  107. Diana

    Does turning off your water heater through out the day and only turning it on before showering, help you use less electricity?

  108. David GRABEL

    Help! My wife keeps turning the fan to off when the house is cool enough and then when the house warms up, she turns the fan to "on"! in this case which costs more, keeping the fan on auto and letting the thermostat do rites work, or turning on and off the fan? Thanks for your help

  109. Monique

    A person who has a brick one story home, to save money on the electric bill is it best to turn the a/c completely off while at work 8-13hrs a day? Once I get home the temperature in my home is about 86 degrees and it stays on all night to cool doe to 78 degrees. Is there a better energy tips for a brick home?

  110. Lorraina H

    I have an electric water heater in my home. If we turn it off for the hours we do not use it does that save us money on the electric bill ? And is it a drastic savings ?

  111. JoAnn Turk

    I enjoy your helpful blog "Ask the Expert"

  112. jim y

    For homes that don't have adequate flow to a room, isn't it cheaper to leave the fan on circ rather than turning the thermostat colder?

  113. Ira Cohen

    What if you have an electro static air cleaner

  114. Don Leonard

    Will our chest freezer use more electricity during the summer if it is in a very hot garage or in the airconditioned house where it generates hot air from the compressorn that will increase our cooling cost.

  115. H Lewis

    We use ac for comfort. At night we leave the fan on "on" to circulate fresh air otherwise the air becomes stale and the humidity goes up when the ac cycles off. During the daytime we put the fan on " auto" so the fan does not draw the warm attic heat when the ac cycles off. Again we use ac for comfort but have you made a cost comparison. Give it some thought

  116. Ed Goldstein

    I would agree that a A/C fan operated in the auto position would be a saving. I wonder if your calculation included the added cost of the inrush current each time the fan is called for . I think it may be small however it is an item. I also think a variable drive and 3 phase motor could save a considerable amount over time. The investment could be paid back most likely in the first year. I would suggest that the speed be adjusted according to when the thermostat calls for cooling and when it commands a shutdown reduce the speed for comfortable air circulation.

  117. Paul Martin

    Is it cheaper to keep light switches on or turn them off when you leave the room,? If one enters and leaves the same room several times per day.

  118. ROBERT BROTMAN

    QUESTION Does leaving CEILING FANS on save A/C cost?

  119. greg

    My wife and I enjoy cool nights and warm days. I'm concerned that turning off the a/c during the day and allowing our place to warm up to 80deg and then at night turning on the a/c to cool to 70deg is costing more than allowing the a/c to run at 75deg day and 70deg at night... am I correct?

  120. Lenny

    Should I turn up temp of ac when leaving house?

  121. Brendan E. Cavanagh

    Does using a dehumidifier along with your AC running help lower the cost . I have to dump about 6 gallons of water out each day and air coming out of the dehumidifier feels warm.

  122. Thomas Hoag

    Would you please give some advice for snowbirds on recommendations for settings of humidistats and thermostats during the summer season?

  123. jeff

    Thou I feel auto mode generally works best the Idea is for the fan to not stop all together makes sense , so if it can ramp down and stay spinning very slowly it would save you money and wear on the fan produced by the forces of coming on hard. SO generally you are right but higher seer, ultra high end, money saving A/C will actually never shut down completely unless turned off.

  124. Joan Gonzalez

    I recently bought a "canopy" that fits over the pull down steps to my attic as a way to save energy. Do you think this helps conserve energy in summer and winter? Thanks

  125. Rita Gore

    This is a question: Do you save money when you turn the A/C off every time you leave the house and then turn it on again when you return? Or does it cost more to get the temp. down after you've been gone?

  126. Matthew Barbaro

    If I live in Florida year round, will keeping my A/C set on 82 continuously avoid mold related issues, or must I keep it set lower to avoid mold?

  127. saul heit

    How much more does it cost to put the computer on sleep mode as apposed to turning it off

  128. Michael Ingenito

    I live in a 5 story Condo,steel,block & concrete construction,I want to install impact resistant insulated windows (Basicly one pane of glass impact resistant,the other 2 panes,with an innert gas such as Argon) is it cost effective & can I get a rebate? the current windows,single pane has no insulating quallity,facing North,I get No Direct sunlight.

  129. Alan

    Have you ever compared the actual time the compressor runs with fan on auto vs. on? My theory (and one reason my fan stays on "on") is that keeping the air circulating keeps the temp a little lower in the house - it this can avoid even 15 minutes a day of compressor time, I should be about breaking even. Also, what about those folks who set their a/c fan to auto, but have several ceiling fans running??

  130. S. Kabani

    How much does it cost to use the A/C only to circulate the air i.e. A/C OFF and fan ON for 12 hours daily? can you compare that to the cost of normal operation i.e A/C ON and fan AUTO ? Thanks

  131. Vivian cohen

    E wich is the better degree for save Montly money?

  132. william poste

    In hot climates, with high attic space temperatures, running the fan in "on" will cause the supply duct rise accordingly, transferring the warmer air to the space and requiring the A/C to run more. In the Northern climates with basements, since most of supply ducts are in the basement, the running the fan in "on" will have little effect on the space temperature, but still use more electrical energy and fan motor wear.

  133. Al Burrows

    My air conditioner/heater guy said leaving the fan on all the time will help prevent repair costs as he said when the fan has to keep turning on and off (when set on auto), it wears it down more. What is the truth on that? Al Burrows

  134. Carol Geissler

    I never knew this. Thanks for the info.

  135. Victor G

    You kind of missed something with the Auto vs On question about AC fans. The point of "ON" is if you don't need to run the AC on cool or heat, but would like to have the air circulation. Then, the On setting makes sense. Although this is rare, in FL winters it might come in handy.

  136. Tony Arcuri

    Doesn't the fan being on Auto, cause hot spots in the house and therfore cause the compressor to stay on longer,m in effect using more electric to re-cool the area.

  137. Albert Palmer Short

    If they like the feel of a fan , why not install ceiling fans. I have three in my home. I go into a room turn on the fan, leave the room , turn it off. Simple and whole lot cheaper.

  138. Walter Waldman

    Once, when leaving home for two months, I left the A.C. fan on the "ON" setting in the hope that the circulation of air would prevent possible pockets of humid air in the dark corners of closets and other enclosures. Upon returning home,I found that mold and mildew had grown on the walls and ceilings immediately surrounding the edges of the air registers. I never left the fan "ON" ever since. Problem solved. The closets were OK, too.

  139. Fernand J. Cyr

    THANKS, for the info on the status of the A/C on or off. This has been a hard item for a neighbor to accept and he's wondering why he pays more for his service per month, his fan is constantly ON.

  140. Jon Haas

    Any owner of a two story home with central air will run the fan on all the time at night to ensure that cool air gets to the second floor. On auto, when the downstairs hits the set point, say 76, the upstairs cool air falls down the stairs. The upstairs will be ten to fifteen degrees higher as a result. Tough to fall asleep when it is 86 to 91 in the bedroom!

  141. Leonard Probst

    My comment is in regard to the question whether to have the A/C fan set to "auto" or "on". One thing you didn't mention was, when the fan is in the "on" position it moves the air around reducing hot and cold spots. If a hot spot forms around the thermostat, it will cause the A/C to come on when not needed. Also when the A/C and fan are off it can make some parts of the house uncomfortable (too hot or too cold). You'll notice in big building, the fans are always on because of that. I keep my fan in the "auto" position because it is annoying when on, i.e. condo with A/C in living area.

  142. Frank

    Is it better to have an Air Conditioning System that is on the "over design", that is if your home requires a 2 1/2 Ton unit would it be better to instal a 3 Ton unit for faster coolin or there is a down side to that option? What are the pros and cons of that option? Would it be more expensive or otherwise besides any other considerations? Thank you for your answer. Frank

  143. RL Paxia

    Is it more efficent to raise the temperature setting, turn the system off or leave the temperature setting to our normal setting (78 degrees) when leaving the office for the evening?

  144. sheryl dunn

    glad for that clarification , that same question always bug me.

  145. Persaud

    Years ago you had a great incentive to help with electricity. You offered assistance with insulating the attic. Do you still have incentives for your customers?

  146. John Cheraso

    Additional support for efficiency regarding "Setting your A/C fan to auto ". Another important factor to consider is convective heat transfer rates. The fan in the "on" position will circulate air past interior windows and walls / surfaces where (as in cooling a structure) this circulating air will pick up heat from the exterior. Since convection heat transfer is the most efficient way to transfer heat from hot to cold then it makes logic sense to reduce the convection i.e. air movement during AC compressor off times. Just some additional thoughts, John

  147. MaryAAmanti

    It was good to read that We are there in winter & leave our a/c on @ 85 & a humidifier on. Our bills there have been good. Mrs. Amanti

  148. Claudia

    Thanks

  149. Scott Smith

    My home has a Florida Heat Pump brand Geothermal heat pump. It is now over 35 years old. When I built my house, I believe the SEER was about 11 or 12. I know that many of the new units are more efficient. (SEER of 18, etc.) And a new unit will save me money on the electric bill. But I am hesitant to buy a new unit because so much of the "new" stuff is just not built to last. And if the new unit wouldn't last, then I wouldn't end up saving anything. I find myself wondering how many others in Florida feel the same way and have older AC units that still work OK. Can I ask the FPL "community" if this is so?

  150. Sergio Perez

    I am an air conditioning expert and have always advised my customers to use their systems on auto during the day and to use the fan in the on position at night. The reason being that the desired temperature setting will be better maintained with the system fan in the on position. This is specially true if the thermostat location is far from the bedrooms.

  151. Alan

    But is there no chance when you leave the FAN ON permanently, then the compressor (which is the big expense) may kick in less often? That is, because you are circulating the air (like house fans would), it takes longer for the temperature to rise, therefore taking longer for the comp. to turn on again. I would it think it's a wash at worst, or provide fair savings at best. Either way I like to turn everything off during a considerable portion of the day, but at night the FAN must be ON. If I allow it to turn ON, I have noticed that the temperature rises very quickly (or at least it feels hotter quickly)...

  152. Mercy Ibanga

    I believe the setting "on" cost more but setting "auto" comes on and off and cost less. My final answer.

  153. Michelle Rollins-Hall

    Along the same lines, my husband and I put the thermometer up when we leave the house for more than 4 hours, and we have 2-zone a/c. The upstairs a/c is set to 84 during the day and lowered an hour or so before we go to bed. Someone told me I'd be better off keeping it one steady temperature. Which way is best?

  154. John Wilen

    In South Florida, condensation builds up on AC vents when the compressor is working and the system is blowing cold air; we leave our fan on at all times to keep air moving through the vents to dry the condensation when the compressor is not running -- that prevents damp vents and pipes from giving mold a chance to start growing. I'll pay a few extra bucks a month to keep the vents dry and mold-free.

  155. Tom Ternus

    Your answer to the question "auto or on" is a bit simplistic. If the ac return and thermostat are located in an interior hallway it may not respond quickly to exterior room requirements. This may require the ac to remain on longer to compensate for higher temps in exterior rooms. At a minimum, the fan on "ON" should provide a more comfortable experience throughout the area.

  156. Charlene Wurtz

    I just had a new A/C installed 2 ton 13 Seer. On what temperature should I leave my thermostat when I'm home at night and out during the day? I live in an 850sq ft Condo in Fort Lauderdale on the west side on A1A. Is 13 Seer enough to cool my condo?

  157. Ronald Lemmon

    What a/c company and a/c unit would you recommend for a 2000 s/f two story town home.

  158. Minnie Holman

    Does running ceiling fans with a/c help? Does it run your electric bill up more?

  159. Robert Southwood

    I have three settings on my AC unit fan,auto and circ which is the best setting to use for the AC

  160. Gini Lee

    I have ceiling fans which have several speeds possible. Does the fan use less energy on the low speed than if it is on the faster speed? Or does it use the same energy as long as it is running on any speed?

  161. William Dobbert

    My Ac system has a 2 speed fan, when the ac system shuts down and the switch is set to "on", the speed is cut down considerably. I think that this setting would be best, since it still circulates the air, but not at high speed so the moisture on the coils will drip off and the moisture in the ducts will still be fanned so as to dry better in there. Is that true or would it still be better to set to "auto"?

  162. steve salem

    Having the fan run continuously keeps the temperature more even in rooms with windows or other heat sources. For me a little humidity also helps my sinuses

  163. Darla Joyce

    When I saw that question in my email from FPL I flipped! Been asking every man I know for years. They were wrong! Mine is on Auto now. Thank you!!

  164. Barbara

    I had a new 16 seer energy efficient Trane A/C installed but they NEVER put in a new thermostat inside the house or changed the electric box outside the house. I am ultimately going to end up in court. Is it mandatory for them to change those items with a brand New System? Thanks.

  165. alvin reitz

    Thanks for the A/C Article. What about during the heating season? On or Auto?????

  166. GERSON BERGAMIN

    And about the other normal fans at the house? Should them be turned on all time for savings?

  167. Lborne

    Fan "ON" keeps the air fresher in rooms with closed doors at times of the year when the A/C or Heat might not kick on for many hours. Sleeping with your bedroom door closed can increase CO2 and decrease Oxygen in your room, but with fan "ON", you are getting fresh air.

  168. David

    I do not disagree with your answer. However those of us who have an electronic air cleaner on our cooling and heating systems have a different reason for keeping the fan setting "ON". The electronic air filter is inefficient if the air flow through it is intermittent. If is most efficient if the air continuously flows through the filter.

  169. George

    Leaving the fan on also continuously recycles warm air into your house from the ducts in the attic. On auto, you only get the small volume of warm air that is trapped in the ducts at those intervals.

  170. Richard Donnelly

    Agree that the ON setting uses more power and dehumidifies less than AUTO. What about some of the new HVAC systems that suggest keeping the system on AUTO and RUN the fan CONTINUOUSLY at low speed? Thanks

  171. Carol O.

    When we are away we set the temperature to 80 and the humidistat to 65 but the condo still seems to have high humidity causing a moldy odour. We have a ground floor unit. What should we set things at to reduce humidity but be cost efficient when we are away?

  172. kim

    Can leaving items plugged in even if not being used, like telephone chargers, televisions, computers, increase your bill/usage.

  173. James

    Your AC provides comfort in hot weather, how much comfort do you want? A continuously running fan keeps a more even temperature. I have window units and I have to set the thermostat on them 5 degrees cooler in auto mode otherwise the room becomes unbearable hot before the compressor will cycle on. Also the fan cycles on and off every ten minutes and at night the relay CLICK wakes me up.

  174. Ron Peter

    Interesting, I have always thought that an electric motor, like the furnace fan, would wear out sooner, due to the start/stop cycle.

  175. ANDREW CASCARANO

    very interesting

  176. Alexander Moir

    Your energy survey takes into account CFL bulbs as the highest energy saving bulb on the survey. I hate to be the first to inform you, but there are now LED bulbs now on the market and I was wondering when you will update your survey to include LED Bulbs and their cost saving factor? I have had them in my house for about two years, including replacing the fluorescent T-32 bulbs in my fluorescent fixtures with the LED tubes. Just wanted to know.

  177. Ken Gross

    I would argue that some conditions require the A/c fan being left on. In my primary residence in Michigan, with the A/C on, there is about a 4 or 5 degree difference in temperature between the 1st and 2nd floors of my colonial. This makes sleeping upstairs difficult and uncomfortable unless I lower the thermostat at night by 4-5 degrees. If I leave the A/C fan on, the difference lessens to about one degree. You have missed the point that the continuous recirculation evens out temperature differences from room to room or floor to floor. You might suggest that those differences should be dealt with by controlling the air flow to different rooms. However, there are limits as to how well the system was designed and how much can be evened out through the adjustment of dampers. I need to have the A/C fan on. In my Florida condo, we get the morning sun on one side of the condo and the afternoon sun on the other side. Without the A/C fan on we are too hot on one side for half the day and too hot on the other side for the other half. Again , the A/C fan on equilibrates things and makes it much more livable. I believe your assessment leaves much to be desired.

  178. Robert Frank

    I have a newer 2 ton a/c unit with a variable speed fan unit that has a DC motor. My a/c company advised that the motor requires the same amount of electricity as a 60w bulb. They also advised that the comfort level would also be equal and allow a higher cooling setting on the thermostat. This however, does not apply when in the heating mode. When heating and the fan in the on position you feel cooler when the heating ceases and the fan keeps running. Does this sound crazy?

  179. ORIN SMITH

    What is the "ideal" temperature to set your AC unit at bedtime for best sleep?

  180. Marcia Kendall

    I received the letter about the Surgeshield and I just wonder if this is legitimate offer. I am on a restricted budget and I don't want to put out the extra money unless it is basically absolutely recommended by you. With the return address being Duluth MN I question it. Thank you. Marcia

  181. Sue

    My question is in regards to A/C auto vs ceiling fans always running: Let's assume that my A/C temp is set to 78 and I have my ceiling fans constantly running. Which will raise my electric bill more? Would it be better for me to lower my A/C temp (with it set to "auto") and turn off my ceiling fans? Thanks

  182. Kirk Menzel

    Believe your approach and answer could be enhanced if you included in the analysis of the power on surge you are avoiding by keeping the fan on. It would be interesting to see how much of the savings gets removed if you included the cost of the powering up the fan from a cold start versus the fan being on the (slower) fan on mode. Thanks Kirk Menzel

  183. Kevin

    In my 2-story house, the 2nd floor is usually warmer than the 1st floor where the thermostat is located. The basement stays cool. Leaving the fan on 24/7 seems to keeps all 3 levels a more uniform temperature. Do you think the extra $8/month for running the fan 24/7 would be offset by the energy savings from: 1) not having to set the temp down a few degrees to cool the upstairs and 2) moving the cool air from the basement up to the living areas?

  184. Florin T

    While keeping the fan on auto may seem to save money in a perfect environment, this is not always the case. Depending on the sun exposure at different times of the day, not all the rooms are at the same temperature. If the fan is continuously on, the temperature in the house is better distributed and warm/hot spots in the house are reduced. In addition to better temperature distribution , just the constant air movement from the fan will give a cooler feel. As a result, one could keep the AC thermostat one or two degrees higher and still feel cool in every room. Therefore, while the fan would use $8/month more electricity, the AC will use significantly less electricity by cycling on less frequent. If one has a UV light installed in the AC duct, keeping the fan on will also greatly reduce the air quality in the house in addition to electricity savings.

  185. RAQUEL

    IT WAS VERY INFORMATIVE WHETHER TO HAVE THE FAN OR AUTO SETTING. I ALWAYS HAVE IT ON AUTO. BUT I ALSO NOTICED THAT LATELY MY BILL HAS GONE UP.

  186. Richard

    Savings could be obtained with leaving the fan 'ON' all the time if it is used in conjunction with increasing the set temperature (i.e. 76 to 77). The air moving around you will make you feel cooler than stagnant air so the slightly increased temperature would not be as noticeable. However, a ceiling fan running in the room you are in and only while you are there would be the best bang for the buck.

  187. marty lowell workinger

    Trying to find out how much per month the cost of running a oxygen concentrator 24 hours per day per month. The other place to pose a question states not able to answer. Please advise as able, I know you can not be exact, but in the range is fine. I am just curious. Thanks Marty

  188. Nelson E Zapata

    Having the air conditioner in auto means that every time the desired temperature is reached the fan turns off saving you a bit of money. However when the temperature increases, the fan draws more current until peak current levels are achieved thus making the bill go up. By leaving it on at least for the time you are at home it would save a bit of money by not drawing any more current that necessary when system comes on to cool the place.

  189. Barry O'Connor

    we keep the temp at 82 while we are not in the house as we are snow birds. We still get bill of up to $200 a month what can help us save money and use less electricity? Barry

  190. David Williams

    Is the an A/C fan that runs on very slow speed while on Auto?? If the cycles are long the house gets stuffy till the next cooling cycle.

  191. Gary Henderson

    I follow and agree with your analysis of a hypothetical situation to answer the question as far as you went. However, I believe you have neglected to consider at least one significant factor. The movement of air across the skin, unless it is heated to something in excess of one hundred degrees, tends to have a cooling effect. Therefore, it is quite possible to maintain the same comfort level by leaving the fan running and setting the thermostat at a slightly higher level. This results in the compressor and condenser motors running for a shorter time period each day during the peak season. There will be times during Spring and Fall where the heat gain from the exterior temp is not sufficiently high that the decreased run time of the compressor will make a difference.

  192. Harry Sultz

    I appreciate your comments very much in that it's nice to update your knowledge and correct misconceptions.

  193. Barry

    I have a new variable speed blower and it has an added feature on the settings. Auto Circulate On In the circulate mode it runs slow and evens out the temp throughout the house. Is this setting OK to use

  194. Rod

    I think the idea behind keeping the fan on all the time is the hope that it will keep the house cooler by circulating the air constantly rather than just when the auto setting turns it on. You only mentioned the additional cost in running the fan all the time. But, IS there actually any cooling cost savings from the fan running all the time? If so, that amount could well offset the extra $8 per month to run the fan.

  195. Mike

    Not only that Craig, but even though my attic and ductwork are insulated, the ducts still heat up a little. When my A/C cycles back on... pretty warm air comes out of the vents until the cooled air gets there. Leaving the fan "ON" would actually circulate that warm air into the house, causing the A/C to turn on more often. Just my observation.

  196. Thomas Jenkins

    Another benefit to running your ac on the "auto" setting is that by cycling the fan off you'll end up with less dust in your filter at the end of the month (or whatever interval you choose to change your filters).

  197. Owen Lavin

    You suggested that running your fan on auto will save money because of the electricity being used to power the fan. I have a three stage DC motor for my fan and it runs continuously on the lowest stage. This helps to evenly distribute the air throughout the house and keeps the second level much more comfortable. When the thermostat calls for cooling, it runs on the second stage for a few minutes and goes to the highest speed only if necessary. This operation has significantly reduced my power consumption over the long run.

  198. Leon

    Aftet upgrading my central unit auto cycles the fan between high and off with the compressor while on causes it to cycle between high and low. This new energy conserving low speed is not the same as off but it does circulate the air slowly. In the summer certain rooms heat up quite a bit before the thermostat activates and this low speed setting controls that. Im an engineer as well and im not contradicting anything fpl has stated but with my newer unit now running on slow instead of high the difference is probably $2 a month instead of $8. I normally activate this if I have guests.. probably 5 days a month.

  199. Kenneth Leber Jr.

    Re A/C fan on/auto. Are there not other factors to consider? For example, if you have a two story house with only one fan and one control system, the top floor normally runs warmer than the lower floor in summer. With the fan on continuously, would you not have better distribution of the air? Also in our Fairfax, Va. house our fan motor had to be repaired because the "Starter" switch went bad. After we began running the fan continuously it ran for 40 years without difficulty, and it was still running when we sold the house in 2004.

  200. Martin

    On the face of it, it doesn't take any real thought process to realize that running the fan all the time will cost more than simply letting it run when the AC needs it to run. I was told the same thing, that running the fan costs less than running the AC but with a twist. What I was told is that if you run the fan more often it will keep the house cooler requiring the condenser to come on less often. With that said, I believe the better question might be, does running the fan all the time, or at least more frequently (I might turn it on during times when it seems warmer than what is being reported) help to keep the house cooler and therefore require the condenser to come on less often? I'm thinking the answer in part is yes, my just turning on the fan would certainly use less energy than dropper the temperature to effective do the same thing.

  201. ernest olivas

    wall fans vs. central air, when you have both. Does running window A/Cs , especially during the heat of the day, save wear and tear on the Central unit and maybe save money by making it run less?

  202. Jim Hauser

    Running the fan continuously can lead to premature failure due to increased heat and friction. The bearings only last so long.

  203. Suzanne Southwell

    Another good tip is to pull the drapes, and/or put down the shades on the west side of the house in the afternoon. The amount of heat coming through the windows is significantly reduced, therefore lowering the a/c bill.

  204. Arie Strobel

    Thanks for that information. One time to leave the fan in "On" position is when you are using the system for heat. Many a/c systems will not work for heating in the Auto position. You know this is probably only necessary info for the Florida customers! Where I grew up we did not have central air let alone a/c units that provided heat!

  205. Scáth Beorh

    Old habits are hard to break, especially when a quarter decade has gone by under the assumption that money was being saved. But if we can't trust the professionals, who can we trust? Thanks for this. Will give it a college try and see what the bill looks like over a 3-month period or so.

  206. Roy

    But if you could leave the temp 1 deg cooler because the air is still circulating, then would it not potentially be a savings? Ceiling fans are suggested to save energy, so does this principle not apply to the a/c fan as well? My a/c fan runs at low speed when off cycle.

  207. Sharon Justice

    when the weather outside drops into the 70's and there's a breeze, is it more or less costly to open the door and use a small fan and turn the AC off?

  208. Bob Burke

    Is a "Circ" setting more efficient than "auto"? This setting turns on the fan up to an additional 30% when the compressor is off. The idea is to maintain a more even temperature presumably at a higher temperature setting.

  209. Roger pennington

    Thanks for tip

  210. Roxanne Duncan

    I just put in a brand new system air/heat the other still worked but was not the new r410 also had some duct work done, bills were getting higher, so I went ahead and updated now. SO my question is should I call flp and let them know I put a new systems in, will it give me any discounts or incentives, other than hopefully a lower bill. thank you Roxanne

  211. JANET JONES

    QUESTION - IS IT GOOD TO TURN THE AC OFF WHEN YOU LEAVE OR IS IT WORSE TO HAVE TO COOL IT DOWN WHEN YOU RETURN?? SHOULD YOU TURN THE AC UP BEFORE YOU LEAVE OR LEAVE IT ALONE??

  212. Dale Puff

    More recently, in 2002, the Integral Fast Reactor was elected the best nuclear reactor design in a Department of Energy report, even though there are no IFR in commercial use today. Does FPL have any plans to build one? Will why not? Since Windmills basically are not reliable, neither is solar. Since Nuclear is the best choice to eliminate all so called carbon pollution. Thank you