Operating Manual
69-2035EFS—05 2
Maintaining ideal humidity
Optimal Relative Humidity (RH) is defined by industry experts* as between 40-60% RH on an
average annual basis, and 35% during the heating season in dry climates. An environment with
too little humidity leaves the body vulnerable to viruses and bacteria, and can cause woodwork
in the house to shrink and crack. On the other hand, too much humidity creates ideal conditions
for mold and mildew growth.
Proper indoor humidity can also help you save money on energy bills. When maintained proper-
ly, your equipment won’t have to run as much because humidified air feels warmer in the winter.
* American Society of Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE)
M24780
0 10 20 30 40 50 60 70 80 90 100
OPTIMUM
ZONE
Bacteria
Viruses
Fungi
Mites
Respiratory
Infections
Allergic Rhinitis
and Asthma
Chemical
Interactions
Ozone
Production
ASHRAE recommeded winter design level