[Weather] 1-wire humidity sensor for outdoor use?

[Tim Bitson]

 Has anyone had the new HIH-4000 fail? I've lost a couple of the older HIH-3610s and have switched over to the the newer 4000 model. It's only been about 6 months...

Tim Bitson


On Tuesday, November 28, 2006, at 12:57AM, "Steinar Midtskogen" <steinar at latinitas.org> wrote:
>[Nafis, Christopher A (GE, Research)]
>
>> I've been using the AAG TAI8540 Humidity sensor mounted in a Davis
>> Radiation shield for an outside humidity/temperature sensor (AAG states
>> "designed for indoor use"). I've coated the circuit board with liquid
>> tape, but the honeywell sensor still seems to "die" after a year or so. 
>> Hobby Boards also sells the HT3-R1-A Humidity / Temp sensor with a
>> moisture resistant coating.
>
>My Honeywell sensors usually don't last longer than half a year.
>After a while, I get 0% readings, or readings stuck at a certain %, or
>they indicate more or less random humidity.  Even new sensors using
>factory calibration are a problem; they sort of work, but without
>further calibration they may report more than 115% in heavy fog.
>
>I've tried a lot of things: different shieldings, different boars (AAG
>indoor, AAG outdoor, Springbok), coating and heating.  The idea with
>the heating was to keep humidity well below 90% at all times and
>calculate the true rh based on the assumptation that the dew point in
>the heated box and in the ambient air is the same.  Perhaps the sensor
>would last longer, but I didn't get a useable accuracy.  Right now I'm
>trying to wrap a nylon sock (from old stockings) around the sensor
>(either the AAG enclosure or the sensor itself), which is suggested in
>the Weather Toys book.  So far it doesn't look too promising as it
>seems to make the sensor very slow and less accurate (though it seems
>to fix the problem with readings above 115%).
>
>My conclusion is that the Honeywell sensor is fine for indoor use or
>in climates where humidity is always between 30 and 80%.  For coastal
>or mountain use, it's a constant calibration and maintenance
>nightmare.  I just had 10 days of continous fog and rain here (i.e. rh
>in the high 90's all the time and about 130 mm of rain/sleet and windy
>at times) and two newly mounted sensors that were matching eachother
>perfectly, were off eachother by 10 to 15% when the fog lifted and
>things dried up.
>