RH problem

[Christopher Thomas]

Responding as an architect, I asked a senior technical architect in our
office for his thoughts. He agrees with Mr. Farrell. The building
envelop needs a vapor barrier. If it is a hot humid climate, the barrier
should go to the outside. If it is a cold dry climate, like here, it
should go towards the inside. 

-----Original Message-----
From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On
Behalf Of Farrell
Sent: Friday, May 05, 2006 10:58 AM
To: Pianotech List
Subject: Re: RH problem

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
>