Relative Humidity ??

[FTC Wines]

This has been puzzling me for a while. My house runs 78* with AC on & humidity 48-50 %. The winery, which has an additional AC unit runs 68* with a humidity of 60-62%. Now I'm not complaining, but I always thought cooler temps held less moisture, so why is the moisture in the winery higher? Air locks go dry in 2ish weeks, but not all. Same carboy, same wine made at same time & one air lock will go dry in 2 weeks & the one next to it might last 4 weeks!! Roy

 

[rhoffart]

Well, this one I know a little about with 25 years in the HVAC business. Actually cooler temps can hold more moisture then warmer.

I'm a little confused ... do you want it less humid in the winery? That will dry your air lock even faster. At 60-62% humidity it should take months to dry an airlock. You sure there is not a different issue? All glass carboys?

 

[FTC Wines]

I'm happy with the 60-62% in the winery! actually surprised, because the house is so dry. And higher humidity IS better for the 700+ bottles in there. Still puzzling is why most of the air locks dry out so fast. Thanks, I always thought warmer air would hold more moisture. Roy. All carboys are glass.

 

[sour_grapes]

Warm air will indeed hold more moisture than cold. However, RELATIVE humidity is the fraction of humidity that the air can hold AT A GIVEN TEMPERATURE.

The air in your house and the air in your winery probably have close to the SAME moisture in them. It is just that this amount of moisture is 62% of what 68F air can hold, but this amount of moisture is only 50% of what 78F air can hold.

 

[sour_grapes]

Okay, I just looked up the absolute humidity in these two cases (using this table). As I suspected, those two combinations of temperature and humidity have close to the same moisture content (i.e., absolute humidity). The air in your house actually has just a bit more moisture than the air in your winery.

 

[FTC Wines]

Paul, thank you for ur posts & the charts & explanations. They made things very clear for me. I now understand it. Really appreciate the effort. Roy