Central air vs. window air-conditioning.

Discussion in 'Shop Talk' started by dlangland, Jul 19, 2005.

  1. dlangland

    dlangland dlangland

    Messages:
    827
    Joined:
    Jul 7, 2005
    Location:
    NW Iowa
    The last 2 places we have owned only had window air. Guys had told me with a window air unit, it needs to be shut off at night so the unit won't overheat. But now, my new place has central air. I am not mecahanically inclined, but people with central air seem to keep theirs running all the time during the heat and humidity streaks. Is that, I would suppose, because if you shut it off, it takes more power to get it back to where it was. I just can't understand that concept, and don't want to be wasting power. I dad one neighbor when I lived in town who went straight from furnace season to air season, only because their house didn't come with screen windows. Me, I enjoy having the windows open.
     
  2. foxtrapper

    foxtrapper Well-Known Member Supporter

    Messages:
    3,693
    Joined:
    Dec 23, 2003
    There's no need to shut a window unit off at night. They don't overheat.
     

  3. Dave in Ohio

    Dave in Ohio Well-Known Member

    Messages:
    130
    Joined:
    Jun 11, 2002
    Location:
    OH
    They may not overheat but sometimes window air conditiones will freeze up and I was told that is because the unit is too small for the area you are trying to cool.
     
  4. pcwerk

    pcwerk Well-Known Member Supporter

    Messages:
    1,961
    Joined:
    Sep 1, 2003
    Location:
    SE Minnesota
    I've heard that window units use more electricity than central units?
    Not sure about that though.
    james
     
  5. agmantoo

    agmantoo agmantoo Supporter

    Messages:
    10,854
    Joined:
    May 22, 2003
    Location:
    Zone 7
    Here in the south AC is more of a necessity than heat or so we seem to think. It is cheaper to set the thermostat on a central unit to an acceptable cooling temperatureand leave it alone. The higher the indoor temp that is comfortable is, you will save money as opposed to trying to operate like an igloo. You will get some dehumidifying as it runs intermittently and once the home is cool the unit will cycle whereas when you turn it off it will run constantly until it cools the home and the contents of the home. My thermostat remains at 78 degrees during the summer. I work outside during the day and I get too uncomfortable if it is excessively cool inside, the extremes are to much to adjust to. My total power billed for the last 33 days averaged slighly less than $3 per day for the house and my shop combined. Geothermal is hard to beat!
     
  6. mikell

    mikell Well-Known Member

    Messages:
    932
    Joined:
    Nov 7, 2002
    Location:
    South West MI
    I have a 5500 btu window unit that cools the whole house including the garage. It's drawing 786 watts by my "Kill-A-Watt" meter it's plugged into.

    mikell
     
  7. Daddyof4

    Daddyof4 Well-Known Member

    Messages:
    1,386
    Joined:
    Jan 4, 2004
    Location:
    GA
    We have a heat pump (Rheem brand) and boy is it junk. Our house is about 1,300 square feet and it won't do the trick. If it is a typical 95 degree Georgia summer day, you won't cool our house below 82 degrees max. We called a repairman out here because it was freezing up all the time and he said heat pumps are not designed to cool any lower than 15 degrees below outside temperatures.

    We eventually had to buy a 5,500 btu window unit to bolster it for the kitchen and the heat pump STILL freezes up. It is a little better but we are considering an 8,000 btu unit for the living room but it seems like such a waste.

    The opposite happens in the winter when it does actually get into the single digits here and the pump would stay on emergency heat if not for our wood stove.

    Our only good experience with a central unit was the old fashioned units from the 70s and 80s.
     
  8. Jack in VA

    Jack in VA Well-Known Member

    Messages:
    434
    Joined:
    Jul 24, 2003
    Mr. Daddyof4..........Find a better repairman, that one was an idiot. If the unit was properly sized, installed, and maintained, it should cool fine and not freeze up. It should drop the temp 15-20 degs. below the INDOOR temp.(Return air minus supply air) Odds are it was not installed properly and you are not getting enough air across the coils.
    And the proper way to use the T-stat is to set it at the highest temp you can stand and leave it alone. The exception would be if you have a setback T-stat, in which case you should set the unoccupied temp at no more than 5-7 degs. higher.Remember its easier to maintain a temp. than acheive it.
    And, yes, it can be a racket. But keep in mind, it's seasonal work, and they gotta make a years worth of money during a few monthes.
     
  9. Virg

    Virg Active Member

    Messages:
    34
    Joined:
    Oct 3, 2003
    Freezing up would be good eh? Kidding. Either the compressor is overcharged or the fan is not transferring the air [blockage]. Or the outside part [condenser] has no way of getting rid of the heat [blockage or bent fins]. Can you hear the pump kick on?
    Window units suffer from low voltage problems, because you can plug em in anywhere.
    REFRIDGERATORS go bad for this reason.
     
  10. Daddyof4

    Daddyof4 Well-Known Member

    Messages:
    1,386
    Joined:
    Jan 4, 2004
    Location:
    GA
    I appreciate the responses from those who know more than I do but I can tell you it was more than one repairman who has told me the same thing and they both said it cools the air 15 degrees colder than outside temps. Both repairmen have been in the business for years and years and come highly recommended by others. That doesn't mean they are right and you are wrong but one fact that even the electric company agrees with is that heat pumps do not heat and cool as quickly or powerfully as a standard central unit. But they make up for it by being more economical (except in our case).
     
  11. tyusclan

    tyusclan Well-Known Member

    Messages:
    4,484
    Joined:
    Jan 1, 2005
    Location:
    Florida
    A heat pump is no different in cooling than any other air conditioner. The difference is in heat mode when the reversing valve goes into heat.

    It is true that when the outside temperatures reach 95+ then your heat transfer on your condensing coil is not as good, so you're not removing as much heat from the house. If you can find some way to shade your condensor without blocking air flow it may help some. Another thing you can do is rig up a pvc pipe with irrigation emitters that spray a fine mist up on your coil as the unit is running. You can get a 24VAC solenoid to turn the water on when the compressor comes on. Then the water is pulling heat from your coil and not just the air.
     
  12. Jack in VA

    Jack in VA Well-Known Member

    Messages:
    434
    Joined:
    Jul 24, 2003
    So.....in Tucson, when it hits 115, it's a comfy 100 degs inside?
     
  13. tyusclan

    tyusclan Well-Known Member

    Messages:
    4,484
    Joined:
    Jan 1, 2005
    Location:
    Florida
    No. An air conditioner that is sized properly should lower the temperature more than 15 degrees below the outside temperature. But you have to remember that heat travels to cold. The refrigerant in the evaporator coil should about 40 degrees. If the air inside is 80 degrees, as it flows over the coil the 40 degree refrigerant can easily absorb the heat because of the temperature difference. The compressor then pumps the refrigeant to the condensing coil at a much higher pressure which also raises the temperature of the refrigerant. That's why the smaller high pressure line feels hot if you touch it. The condensing fan outside then pulls air over the coil to absorb the heat that has just been brought from inside and blows it out in the air. That's why the air feels warm over the condensing fan. If your outside air is 80 degrees you have a wide range between refrigerant temperature and air temperature and good heat transfer. But when you raise the outside temperature to 95 or 100 degrees, there isn't as much difference between the air and refrigerant temperatures and your heat transfer is not as good. Because the 95 degree air already the heat required to raise it to that temperature, the amount heat the air can absorb has been reduced by that much. By shading the condensing unit or putting the water on the coil you increase the amount of heat that can be transferred from the refrigerant.
     
  14. dlangland

    dlangland dlangland

    Messages:
    827
    Joined:
    Jul 7, 2005
    Location:
    NW Iowa
    Strange, even the window air of my SD house keeps the main 2 rooms at a consistent 76 degrees even when it is over 100 degrees real temp, not heat index, and the back side of the house, the kitchen and downstairs bedroom, around 80 even in a heat wave. Yes, I had it measured up for the proper BTU whatever. of curse, it doesn't do a thing for the upstairs, but neither does the central air at my new old house in Iowa. Lack of ductwork. going to be cold up their this winter, too, but my bedroom so downstairs, and I will only need to worry about the upstairs when my daugher is home from college on occasion. I was thinking of putting my window air in the upstairs open loft to use when she is there, but maybe I'll just make her camp on the sofa downstairs during the heat waves.
     
  15. fordy

    fordy Well-Known Member

    Messages:
    9,305
    Joined:
    Sep 13, 2003
    Location:
    Whiskey Flats(Ft. Worth) , Tx
    ...............I'm a firm believer in Window units ! My framed in living area is 16 x 40 . I use 2 , 6000 btu , 9.7eer , window units which usually last about 4 to 5 summers . When they crapout I just put'em in the dumpster and purchase another new unit . Beats the heck out of spending 2 or 3 thousand for central heat and air . Just this afternoon , I purchased a New , 6200 btu , 9.7eer window unit to replace the 8 yr. old unit that I use in my bedroom and I'm expecting IT to Crapout before the end of the Summer . This new unit cost me 128 plus sales tax at W\M . Had I waited till the end of August and my older unit failed my selection(s) would be limited to the Small units and the Very large units . I have learned the hardway way about NOT being prepared with a Backup unit . Here in Texas I will usually run my bedroom unit until the middle of Oct. or later just depending upon how long the heat hangs around . Trying to sleep at night in Texas during the Summer w\o airconditioning is darn near impossible . fordy.... :sleep: :eek: :)
     
  16. dlangland

    dlangland dlangland

    Messages:
    827
    Joined:
    Jul 7, 2005
    Location:
    NW Iowa
    Do you know what I most enjoy about this place? Every single question I have asked...I am thinking to myelf...this is so stupid...they are going to make fun of me, but everyone is so very helpful. But the fact of the matter still remains, as in my original concern, now I am supposedly the proud owner of central air. And it is very nice.When I am at that house, I enjoy that is so quiet, doesn't seem like it runs all that often...I feel spoiled. The window air of my other house...so noisy. Maybe it's just me, but I don't about central air. ( I sure know it' snice not to have o worry about...lets not run the air, make toast, plug anything in the kitchen, and don't you dare turn on the bathroom light, because that is the kind of wiring I had in my old houses. Woops. Let's pop a couple fuses in one afternoon.

    My dad tried to tell me it will cool the upstairs if I keep a window cracked....How, if I have no heat ducts in the upstairs. I know the old hot air rises theory...My dad is a very handy man, and I like to think he knows everything, but he has never central air either. I disagree with that statement.
     
  17. Jolly

    Jolly Well-Known Member

    Messages:
    5,511
    Joined:
    Jan 8, 2004
    Location:
    Louisiana
    Heat pumps?

    Most guys down here in this region of the Gulf South won't even fool with them.
     
  18. hollym

    hollym Well-Known Member

    Messages:
    2,314
    Joined:
    Feb 18, 2005
    Location:
    TX
    Dlangland, if you have good screens on the upstairs windows you can open them at night and buy one of those fans that have two side by side, one that blows hot air out, one that pulls cool air in. That, and a box fan on the person sleeping keep us comfortable, and we are in Central Texas. Now daytime is another story, lol, but we do sleep in a bearable temperature at night.

    hollym