features · humidity measurement for air ducts · simple and secure installation · 0…10v or 4…20ma measuring signals · compact size and modern design applications · on return air ducts to measure return air humidity · on supply air ducts to measure supply air humidity · on fresh air ducts to measure outdoor ari humidity. humidity tansmitter the transmitter measures the humidity by the honeywell humidity sensor hih-3610. the transmitter analog output may be be 0-10v or 4-20ma. and the transmitter include a noise filter.the power suply is large range vdc18v----vdc30v.the humidity transmitter measurement range is 5%-95%.