My best guess is that the ceiling and upper walls are poorly insulated. These are outside walls? The dew point for 40% RH and 72 degrees F is 46 degrees. So if it was 36 degrees F outside and the walls were around 40 degrees F or so, condensation will occur on the walls. I thought Europeans used the Celsius scale for temperature. Terry Farrell ----- Original Message ----- From: "Ric Brekne" <ricbrek at broadpark.no> To: <pianotech at ptg.org> Sent: Friday, May 05, 2006 9:34 AM Subject: RH problem > Hi folks > > We just got done installing a humidity system in an organ room here at the > University I work for. The thing has a humidistat and it was set to 40 %. > During the last bit of the cold period here the outside temperature > hovered around 36 degrees and we keep inside temps around 72 %. The > inside RH was at 25 % with the unit turned off, and going on max it came > up to just under 40 %. All seemed well. > > The cold period ended and the last 3 days has seen very warm outside > temps... upwards of 80 degrees F. RH continues to be low ... outside > around 35 %. However we walked in the room this morning and found green > fungi beginning to grow on the ceiling and obvious signs of condensation > on the upper walls. Fortunatly the humidifyer was pointed away from the > organ and that part of the room seems uneffected. > > What I dont really understand is why the condensation ? Inside RH levels > remained nomally over 40 % the whole time as far as we can see. The only > thing that was different was the temperature. That would suggest the > humidistat was working correctly. > > Any good explainations ?? > > Cheers > RicB >
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