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why ac units use hot air, not re use cold air


trevor borocz johnson

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Does anyone know why air conditioning brings in hot air from outside instead of re using the air it has already chilled?

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Because the fan only blows one direction?

From the outside in?

Punchline imminent? :mellow:

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2 minutes ago, .ZZ. said:

Because the fan only blows one direction?

From the outside in?

Punchline imminent? :mellow:

no answer on google and are you confused? I said re use the chilled air in the house instead of bringing it in from outside.

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Just now, trevorhbj said:

no answer on google and are you confused? I said re use the chilled air in the house instead of bringing it in from outside.

You're the one that sounds confused.

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my guess is the moisture coming in drips on the outside because it gets cooled by the freon and its to much to catch the water so it has to go!

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Oh I guess it does re use the air in the room but it still sends the air in the room out the window. how does it know which air has been chilled and which is hot? it runs constantly. I'm talking about window units. I still think a standing unit continuously cooling the same air without getting the outdoors involved would work better.

Edited by trevorhbj
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30 minutes ago, trevorhbj said:

Oh I guess it does re use the air in the room but it still sends the air in the room out the window. how does it know which air has been chilled and which is hot? it runs constantly. I'm talking about window units. I still think a standing unit continuously cooling the same air without getting the outdoors involved would work better.

It's a good question and I'll do a little research because I'd like to know.  My guess is that recycling air that had already been chilled/dried would reduce the humidity to unacceptable levels.  Off to see the Gizzard!

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Amazing invention for 1902 isn't it? I just recently bought a floor model myself, the exhaust ports to a small window kit, making it much easier to take out on nice days and I can just roll it around to wherever. However I'm no expert but window fans suck air from inside to circulate over the cooling coils which are probably going to be a specific temp regardless of the air temp passing over them, the hot air expelled is to prevent the compressor from overheating. I assume that the liquid entering the evaporator coils, allowing it to expand to gas which in turn cools quickly is completely irrelevant to how cool the air entering the A/C actually is. Perhaps the cooling effect from that rapid exchange is going to be the same temperature regardless of the surrounding temperature.

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All air conditioners work essentially the same.

http://www.newair.com/kb/window-air-conditioner-unit-works/

 

asv-window-unit-ac.jpg

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ac use both, depends on particular ac, however intake of fresh air is preferable since rec. air is dry. 

cars have rec button that recirculates the air, like 95% of air is sucked from the inside, cools off faster, but you do not want to keep it like that for long. air gets too dry, and you become less alert and makes you wanna sleep. 

Edited by aztek
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Put plastic bag over your head and seal it around your neck. How long will you breathe? Recycling same air is exactly the same plastic bag, but a bit bigger...

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On 5/27/2017 at 3:06 AM, bmk1245 said:

Put plastic bag over your head and seal it around your neck. How long will you breathe? Recycling same air is exactly the same plastic bag, but a bit bigger...

lol, if plastic bag is big enough, then i can breathe for very long time,  actually i will get co2 poisoning before the bag runs out of o2. those 3 meter inflatable balls that people run inside of, have enough volume to breathe  for about 10-15 min. 

split units, which are used in pretty much everywhere except usa and canada, where they are not as popular,  are exactly that. they have no fresh air intake.  a cracked open window will get some fresh air, our window units have a small flap that allows fresh air come in. 

Edited by aztek
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Trevor, I am confused by your question...  Is this a refrigerated type air conditioner?  Brand/model?  Is it actually in the window as you described, or is it portable with a tube that goes from the unit to the window?

If it is the former (in the window), it mostly does use inside air and recirculates it, but it also very likely has a slider control so you can introduce some outside (fresh) air. It will work more efficiently if it recirculates the inside air, but the air may become 'stale' and get excessively dry.

So most air conditioners of that type are designed to mostly use recirculated air - in other words the fresh air vent, if there is one, is likely small.  The part outside is the coils which are taking away the heat, and there may be a fan blowing air over them to cool those coils, but that air has nothing to do with the air inside, and is different to the small amount you may allow in via that Fresh v Recirc slider.  The ones with a tube (or at least those that are refrigerated) use that tube to exhaust hot air to the outside after it has been used to cool the coils - they don't suck air in from outside...  So again, they do recirculate the air.

Split system air con's also generally recirculate most if not all their air.  Again, that outside fan is just used to cool the coils containing the refrigerant.

If it's an evaporative air conditioner, then the answer is different.. but I suspect you are just misunderstanding what the stuff outside the room actually does..

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To reverse the topic ;  Ahhhhh  ... for one of those old wood heaters we used to have at Golburn  ( a very cold place in winter )   constant warm fresh air in  ( via a through the wall event then pipes through the heater out to an inside air vent  ), cooler stale air out  ( via a low level fanned air scoop that fed the fire box, and exited up the chimney ).    Totally sealed house, fresh warm air .

They made them illegal here  .   :(  

 

Air con here works very different ( no mains electricity )  ; high vents in rooms to outside for hot rising air escape, which draws air in through floor vents from under house , which draws air in under house, through  surrounding  attached floor to ground vegetation (  so floor must be suspended)  which is kept wet by drip line or micro-sprayers .  

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28 minutes ago, back to earth said:

To reverse the topic ;  Ahhhhh  ... for one of those old wood heaters we used to have at Golburn  ( a very cold place in winter )   constant warm fresh air in  ( via a through the wall event then pipes through the heater out to an inside air vent  ), cooler stale air out  ( via a low level fanned air scoop that fed the fire box, and exited up the chimney ).    Totally sealed house, fresh warm air .

They made them illegal here  .   :(  

 

Air con here works very different ( no mains electricity )  ; high vents in rooms to outside for hot rising air escape, which draws air in through floor vents from under house , which draws air in under house, through  surrounding  attached floor to ground vegetation (  so floor must be suspended)  which is kept wet by drip line or micro-sprayers .  

It's a pity that with all the new tech, we drop this sort of excellent thinking - those systems work really well.  And then we install air conditioning systems and (rightly) whine about the huge electricity bills and the enormous cost of supplying it, despite the fact that homes now use energy efficent tech, led lighting, low power tv's, etc..  Yes, of course we are paying shytloads more for electricity - now that it has been privatised we are also paying shareholders dividends and for the overpaid basstards that run the global conglomerates that buy all this stuff...  Yeah stuff gets so much cheaper when you privatise....  </rant>

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On 5/28/2017 at 6:47 PM, aztek said:

lol, if plastic bag is big enough, then i can breathe for very long time,  actually i will get co2 poisoning before the bag runs out of o2. those 3 meter inflatable balls that people run inside of, have enough volume to breathe  for about 10-15 min. 

split units, which are used in pretty much everywhere except usa and canada, where they are not as popular,  are exactly that. they have no fresh air intake.  a cracked open window will get some fresh air, our window units have a small flap that allows fresh air come in. 

Ok, fair enough.

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