If the temperature of the air coming out of the vent is constant, and it's at 100% RH (theoretical), when it's mixed with and attains a higher stabilized temperature, the RH will be lower, but the amount of moisture in the air is unchanged. Here's a chart I found that should help. -------------- next part -------------- A non-text attachment was scrubbed... Name: Relative_Humidity.png Type: image/png Size: 54200 bytes Desc: not available URL: <http://ptg.org/pipermail/pianotech.php/attachments/20090830/33733a14/attachment-0001.png> -------------- next part -------------- Taking an example that has been used previously of the air coming out of the vent at 40F, which is approximately 5C, it shows that the grams of H2O / kg of air is about 7 grams. You take that same 7 grams of H2O and warm it to 68F, which is 20 C, it is approximately 40% RH. From what I've read, isn't 42% RH at 68F the ideal environment for a piano? Regards, Rob McCall Murrieta, CA On Aug 30, 2009, at 06:11 , Andrew Anderson wrote: > Water does not have to condense (greater then 100% Rh) out of air to > increase MC in wood, it simply has to be available in the air, > greater Rh = greater availability. We don't like to see pianos > sitting in 60% Rh without a stringcover at least. What about 80 to > 90% Rh coming out of a duct and blowing directly onto the piano? > > Andrew Anderson > > On Aug 30, 2009, at 4:22 AM, Terry Farrell wrote: > >> How is cool air blowing out an air duct going to "give up its >> water"? If the air was at 100% RH at the coils, it will be at 99.9% >> RH or lower as it exits the vent - how is it going to loose any >> more water? >> >> Terry Farrell >> >> On Aug 29, 2009, at 10:01 PM, Andrew Anderson wrote: >> >>> SNIP >> >>> Cold air straight out of a duct (short ones make this obvious) has >>> a high relative humidity and can easily give up its water. >>> >>> Andrew Anderson >> > >
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