Topic: New VP2 reads 0.5C lower

[4wd]

My original VP2 is about ten years old and looks it, so as a birthday present I bought myself a new main unit.
At the moment they are side by side and the new one reads 0.5C lower and 4% lower humidity
That might seem reasonable sensor drift except the T/H sensor was only replaced in the old one last October!
While you wouldn't expect them to read identically this seems quite a troubling discrepancy.

The humidity difference is neither here nor there but I'm reluctant to set an upwards offset on the new one.

[CW2274]

I'm assuming when you replaced your sensor last you graduated from an SHT11 or 15 to a 31. With that, did you account for the -0.5C offset that is required with older VP2's when installing an SHT31?

[4wd]

The one I replaced with appeared the same as the previous one replaced 4 or 5 years earlier but if the offset should be 0.5 that's mighty suspicious!

[CW2274]

The one I replaced with appeared the same as the previous one replaced 4 or 5 years earlier but if the offset should be 0.5 that's mighty suspicious!

Suspicious? No, it's fact. Older VP2's ISS transmitters are of a different protocol that require the offset when used with an SHT31. Yours applies.

[4wd]

This is the sensor would have been in from about 2014 until late last year, is it the older type?

 [ You are not allowed to view attachments ]

[CW2274]

This is the sensor would have been in from about 2014 until late last year, is it the older type?

Yes.

[CW2274]

https://www.manula.com/manuals/pws/davis-kb/1/en/topic/temperature-humidity-general