Two Questions about Window A/C Units

[Dan C]

Should be from the outside. Some units have a selector switch for fresh/recirculate.

Same answer.

[Chip C]

I think few new units have fresh-air intakes, in the name of efficiency, assuming outside air is hotter than inside air so would take more energy to cool. A bit of a shame since often the A/C is blocking the only window that you could open for a breeze on a nice day.

Chip C

[Julie P.]

1) Do window A/C units, when set on the fan only setting, blow fresh air in from the outside, like a regular box window fan, or recirculate air from the inside?

2) Same question, but with the A/C turned on. Does the air come from the outside or inside?

Because I have my window A/C set to fan only, and even though it was freezing outside, it was blowing warm air!

Thanks!

[Julie P.]

Thanks Dan! But then why is the filter right along the front (inside the house) grill of the air conditioner? And why is dust forming on this same grill? It seems that the AC unit is sucking in air from the inside via the grill then filter?

J.

[Julie P.]

IOW, the filter rests parallel to the inside face of the A/C unit where the controls are. It would seem the air would have to be coming from the inside.

[webmaster]

Most units only recirculate indoor air. Some units have a small flap that is controlled that allows a very small percentage of outdoor air to be pulled in, but its almost worthless.

See the above answer.

Then guess what? Yours was recirculating indoor air.

[Mark]

Any window unit made in the last 20+ years will have an adjustable flap that allows some outside air to be mixed in to the room air passing over the cooling fins. You can adjust it so that it is taking mostly outside air all the way to no outside air.

For efficiency purposes related to cooling, you would want to close out the outside air so you are just cooling inside air over and over.

[Steve B.]

The air comes from the inside. It is pulled through the filter then the evaporator and blown out the vents above. Some units have a selector you can turn that will open a small door to let fresh air in to the stream or to blow stale air out but this would only be a fraction of the air.

It works the same way. Doesn't matter if the compressor is running or stoped.

Steve B.

[Steve B.]

Yes you are correct that the air is coming from inside. If there is a fresh air selector on the a/c it opens a little door in the air path so fresh air from outside is drawn in to the air stream (about 10%)

Steve B.

[Julie P.]

Thanks Steve and to everyone else who answered! This explains why I am getting warm air then with the fan-only setting. I had to run the A/C even when it was cold outside, since the heat inside always runs inside the house, making the temperature 76-77 degrees F. inside at all times! The thermostat was fine, but something was wrong with the furnace so it almost never stopped running, even though the thermostat was set at 58 degrees F.! But my landlord finally called a furnace tech after a few weeks, at my insistence, so hopefully this won't go on too long!

[Julie P.]

I know! When it is not hot enough to run the AC, but you still would like fresh cool air blown inside, a window A/C unit is basically useless! And I'm not going to uninstall it and replace it with a box window fan everytime I just want fan only!

[Edwin Pawlowski]

Inside air. Even the ones with a vent onlybring in a tiny amount of fresh air. I was told by one of the engineers at a major AC maker we suppliied that "it is a selling point".

Same answer

Yes, that is a problem with window AC if you have only one window in the room. Aside from taking it out, no easy way to get fresh air inside.

[Julie P.]

Strange, I can't find this on any of my four air conditioners (3 Daewoo, and

1 Whirlpool). And all were bought new in the past 1-3 years!

Except when you are running the fan only setting and it is cooler outside than inside!

[mike60510]

This is a new high for this newsgroup. No one flammed her or told her to go to alt.home.repair.

[Scott McDaniel]

No, the "default" is to recirculate. If the unit doesn't have a "fresh" switch/lever, then the unit will ONLY recirculate ...

See above ... and it would make little sense to set the lever to "fresh" if you were attempting to cool the air ... it's kinda hard, in the middle of summer, for your window unit to cool 95 degree air ...

[Scott McDaniel]

This is much more of an issue in commerical buildings than anywhere else (due to the much larger numbers of ocucpants). The average home has, what, 4 people in a 2000 sf enclosure ... unless the home is exceedinly tight, infiltration and the occasional comings and goings will provide ample fresh air. And, in this particular case, since the poster is talking about window units, I'm making the assumption that the home isn't terribly tight ...

[PrecisionMachinisT]

Steve,

Mostly been just the "Kevin and Bill show" there for the past couple days--hopefully, those nice men with the white coats won't let Matt back out till his new meds kick in.

IOW, probly fairly safe to go back now...

Cheers,

[Beachcomber]

Basic Principal of Economics Here

All air-conditioners are designed to re-circulate the indoor air. In addition to cooling the air, the second, but equally as important job of an air conditioner is to de-humidify the inside air. If they just sucked in 100% outside air, the cost to cool and de-humidify that volume of air would be incredible.

The little fresh air vent that has been described on most A/Cs is just that... A way to provide a little bit of fresh air from the outside without excessive expense.

Lack of fresh air is why some people feel sick in an air-conditioned space. Your breathing the same CO2 and other byproducts of human respiration over-and-over. If not enough humidity is taken out of the air, you will feel cold and clammy.

Beachcomber

[webmaster]

GEE..thats cause its CROSS POSTED to alt.home.repair. Im done with alt.hvac. Not due to the regulars, but due to the trolls that invaded..you would not be one of them would you?

[PrecisionMachinisT]

Unwess one of em happens to get onta da wong twack...