Humidity Sensors


Thread Starter

Michael Lord

I'm looking for an article explaining the problems of using humidity sensors at high levels of relative humidity within A/C ducts due to moisture buildup on the sensing element.
Hanna Instruments is a world leader in portable test equipment.
The stated accuracy of their 'humidity' (Hygrometers) is ± 2% @ 25 deg C.
Their Web site (on my catalog).
You may ask for Serge Breton.
In their catalog, section L includes several pages of tutorial.
I do not know of one but there might be some kind of answer in the article written by one of the hvac filter companies---i think it is either
farr or cambridge filters. they recommend that the duct following any ahu be kept at 80% rh or lower, the idea is that when the temperature fluctuates for any reason then the cold ductwork and fittings will condense moisture in the air, eg the duct is running at 10degc then due to some disturbance the air goes to 12 degc, the water content of the air is higher than before and it will condense from the 12degc air onto the 10degc duct and fittings. hope this helps.