Les,
RH levels in excess of 25% during periods where the outside temperature is 0
degrees F or less can deteriorate the building structure according to ASHRAE
( American Society of Heating, Refrigeration, and Air Conditioning
Engineers). All the humidifier manufacturers recommend adhering to the
following chart:
Outdoor Temp Recommended Max.
Degrees F Indoor Humidity %
---------------------
-------------------------------
+20 35%
+10 30%
0 25%
-10 20%
-20 15%
A home air conditioning system will generally drop the RH level to 60%. I've
not seen a situation yeilding less than 60%
This leads to, 60% in the summer and 20% to 30% in the winter. If this 30 to
40% swing produces satisfactory results then stay with it. If not, and you
want tighter humidity control, you may wish to install a Dampp-Chaser
humidity control system.
Bob Mair
Dampp-Chaser Electronics
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