Siemens POWERS HU 186 Technical Instructions

POWERSTM ControlsTechnical InstructionsDocument No. 155-027P25HU 186-1February 14, 2005HU 186 Room And DuctHygrostatsFigure 1. Room Hygrostat. Figure 2. Duct Hygrostat.Siemens Industry, Inc.Description The HU 186 Room and Duct Hygrostats are pneumatic instruments sensitive to slightchanges in relative humidity. They feature adjustable sensitivity and bimetal temperaturecompensation to minimize temperature effects. The room hygrostat comes complete withstandard cover and wall plate. The duct hygrostat is shipped inside the duct mountingbox.Product Numbers See Table 1.Application The sensing element of the HU 186 hygrostat consists of a highly sensitive hygroscopicmembrane. Typical applications include comfort control of hospitals, schools, and officebuildings. More critical applications include the control of humidity in museums orcomputer rooms.Figure 3 shows a typical application of a room type hygrostat. The duct hygrostat wouldbe used when humidity sensing is to be done with a duct sensor. For most applications,the best location for a duct sensor is in the return air duct.Figure 3. Application of Room Hygrostat.