The dead-of-summer oppressive heat and humidity have settled into the Midwest, it seems, and as I cranked up the a/c a thought occurred to me. On ridiculously humid days like yesterday, I’m cooling the inside air to below the outside dewpoint (to wit: the dew point was 79F, and I had the thermostat set to 75).
Since when the dewpoint=air temperature, the relative humidity is 100%, and generally fog and such start to appear. So therefore, since I’m cooling 79-dewpoint air to 75 degrees, I should be getting condensation on the walls and maybe even bits of fog forming in the living room. But I’m not. Why?
Many air conditioning systems have dehumidifiers. See if you can dig up the manual.
-Beeblebrox
“The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at or repair.”
Hopefully I’m not overly simplifying this but: it’s my understanding that the AC not only reduces temperature, but also humidity. So, while fog might begin to form if you simply lowered the temperature (think of days when it’s hot inside and the fridge/freezer has fog coming out of it when opened), you are ineffect removing excess moisture from the air and spitting it outside of your house.
Don’t tell me you have not noticed A/C remove humidity from the air. Your A/C starts removing humidity from the air much faster than it is removing heat. It is drying the air faster than it is cooling it. Humidity is condensing in the evaporator coils.
The air conditioner works by passing cold freon through coils of tubing, and air from the house blows over these cold coils. As the air passes, water vapor from the air condenses on the coils, just like it does on any cold thing exposed to warm humid air. The condensation drips off and has to be drained somewhere. So dehumidifying is an inevitable result of how air conditioners work.