I don’t understand some of the vpd apps. Some will read 1.1 while others show it as 19.7. I have an app called VPD Buddy and in one section it shows the void as 1.1 but in another section, it shows it as 19.7. Why the difference in numbers for vpd.
I just follow the basic vpd chart you can Google. There is one by Omni something or other and that’s what I use. Find the columns for the current temp and rh and where they cross is my vpd. It’s always spot on with what my environment controller is reading.
vpdchart.com is what I use.