On May 13, 2009, at 11:42 AM, Don Mannino wrote: > I would suggest that your 25% low number could be the result of a > not so accurate humidity gauge. This is a common low limit for many > electronic gauges, so if that is what you are using, try a better > one, or a sling psychrometer. I have found that a sling psychrometer has practical lower limits. I think the water evaporates too fast to get the temperature of the wet bulb down as low as it would go theoretically. In any case, I could never get mine to read much below 20%, and the figures on the charts (wet bulb/dry bulb) rarely go that low. The CMM880 from Pianotek seems to be pretty good at low ranges. Seems to do consistently well even in the 1-10% range (5% is about the lowest I have had in a building, but in the car on a hot, dry summer day I have read between 1 and 2). In Tennessee, it should be possible to maintain a fairly high lower limit without too much trouble (35 - 45%). That is, it doesn't get cold enough to create the condensation problems Don described (partly this depends on the building's design and construction). The more expensive side is in reducing humidity in the summer, which is usually done by supercooling air. If you can actually get to talk to the engineers and designers, I would ask questions about what is feasible and practical. I would definitely not be demanding a window of 4% (the 48 - 52% you mentioned). From the point of view of asking for more than you expect, I would make my ideal 45 - 55%, and settle for 35 - 65% as a marked and livable improvement. Regards, Fred Sturm University of New Mexico fssturm at unm.edu -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://ptg.org/pipermail/caut.php/attachments/20090513/9d9f84f4/attachment.htm>
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