Honeywell H8908B1010
Honeywell Humidistat Manual Color Taupe
**Obsolete** use H8908ASPST as replacement.

  Manual Manual Automatic Automatic

The H8908B Humidistat provides manual low voltage (24 vac) control of humidifiers, in central heating and air conditioning systems. The H8908B has a SPST, snap-acting, dust-proof switch and designed for wall or surface duct mounting. Same as H8908B1002.

Color: Taupe

√ SPST, snap-acting, dust-proof switch
√ Positive ON and OFF settings
√ Twelve-inch ribbon of thin nylon ribbon
√ Mounts in duct or on wall surface

Product Specifications

Description Humidistat
Application Humidification
Type Humidity Control
Voltage 24 Vac
Electrical Rating 50 VA at 24 Vac
Color Premier White
Mounting Duct mount or wall mount
Differential 4% to 6% RH
Temperature Range -20° F to +120° F
-30° C to +49° C
Operating Range 10 to 60% RH
Dimensions (in.) 3¾ in. high x 3¼ in. wide x 2 in. deep
Dimensions (mm) 124 mm x 82.6 mm x 50.8 mm deep

Manual Versus Automatic Humidistat

The indoor humidity level needs to be set based on the outside temperature. This is to prevent water from running down the windows. The cool air near the windows can not hold the humidity and water will condense on the glass. To prevent this condensation, the indoor humidity level is sacrificed by lowering the humidistat.

An automatic humidistat (Aprilaire 60) adjusts the humidity by using an outside temperature sensor.

The Aprilaire manual humidistat as used in earlier Aprilaire humidifiers (Model 4655) requires adjusting the relative humidity based on the outside temperature. A manual humidistat needs to be set back as the season gets colder. The chart below shows the humidity setting for a range of outside temperatures.

When The Outdoor
Temperature is
This Relative Humidity
Should Be Maintained
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