My house is sealed well, so this does not reflect the true readingFor this to be true, you'd have to actually create a measurable pressure difference between the inside and outside, as in opening an outside door would equalize it. Do you really think you have that?
This was a guess on my part. I Have to use the calibration settings on the upload software to get the output to show what is actually out there. My 5 in 1 unit is at 254 Ft elevation, but to get it close to what it really is, I had to jack its output to calibrate for 350 Ft.
I guess the main thrust is, shouldnt have to calibrate it, but if I do, it should be an adjustment i can do from/on/with the equipment, instead of the software i upload from.