We had the carpets cleaned in January one year. You know when it’s a bitter cold 60 degrees in Southern California. Carpet cleaner wanted us to crank the A/C because carpet would dry faster. Cliff told me that was wrong, but I bundled up anyway and crawled in bed for the afternoon with the electric blanket because I figured the guy should know his business. Eventually we turned the heat on instead.
There are two things to consider. One is relative humidity, the familiar % that is reported. That a key driving force for evaporation. Because hot air can hold much more moisture than cold air, simply heating the air results in faster drying. At a typical 50% relative humidity for January in Los Angeles, at 60 °F that air would have 0.0055 lb water/lb of dry air. At saturation (100% humidity, where no further evaporation could occur), the air would hold
If we take that same air and simply heat it to 90 °F, the relative humidity drops to 18%. That increases the driving factor for evaporation. It also means that as air evaporates from the carpet, the humidity will stay lower, thus sustaining the driving force for evaporation.
The second factor to consider is the heat of vaporization required for water to change from liquid to gas. Warmer air contains more heat, which enables more water to evaporate. In other words, even if cool air and warm air have the same relative humidity (and thus the same driving force for evaporation), water will evaporate faster in the warm air than in the cool air.
We just got here to start our month long vacation.
