Ok... it's been a long time since I've posted this...thanks to the response email service of wxforum
Well… Firstly I had a SHT11 that came with Davis Station in 2011. The max humidity I got was about 96-97%. Since that moment I thought that that value was not very accurate in foggy nights.
I've purchased a SHT75 with better humidity specs and I found that in high humidities was just the same about 96% for the max. So... when I saw that SHT31 by Davis was in the market I've got it and put it on my Davis station…. just disappointed with the results… 96% in max values too and in the middle range a 2% lower of humidity compared to the SHT75.
I've then purchased a SHT31 and SHT35 from
Closed Cube and with an Orange Pi PC (similar to the Raspberry but cheaper) I put it both into Davis Station with a cat 5 cable. The SHT31 with i2c protocol was similar in middle ranges to SHT35 and SHT75 (put as main sensor on station) but in high humidities the values was of 96-97% again. Only the SHT35 reached values of 99%.
Also the variation time was better. I think just like it is said in the link above (thanks for it jgentry
) the size of the filter cap could affect the variation time. The SHT35 with SF2 Cap filter from Closed Cube is just closed to the sensor leaving no air chamber between, not like the Davis sensors where there is a big air chamber that needs more time for renewing the air.
After I've purchased and saw the results of Davis SHT31 I wrote to Davis asking if SHT35 was coming soon and they said to me that it wasn't in their plans. I'm a big disappointed why Davis for just 8$ of difference between SHT31 and SHT35 mount in their units the cheapest one. I think Davis is there to improve and install high-end sensors (just a difference of 8$...for God's sake !!)
Actually I've put +0.1ºC and +1% offsets to SHT75 in Davis console and is giving similar values in SHT75 and SHT35
http://meteoarchena.es with the Davis SHT75 and
http://meteoarchena.es/sht35.php with the i2c SHT35. Observe that max/min values are quite similar but in high humidities and in response time SHT35 makes the difference.
The 75 is plug and play with a Davis ISS. Apparently the new one will be based on the SHT35-DIS so it'll probably be I2C.
Yes... I'm afraid of that… the sht35 from Closedcube is cheap and handy for mounting with pre-soldered headers