superheat hvac buddy

[question mark]

hi guys,
just recently, I bought a HVAC buddy app. but i feel some thing is wrong.
to calculate superheat , i plugged in 60 psi suction presure for r22 and suction line temp at 7 deg celcius. and the answer was -11.8 actual superheat .

If i would have done it on paper i would do suction line temp 7 deg celcius -60 psi(1 deg celcius)= 6 deg superheat. however app tels me -11.8 actual superheat. sorry i can't get it

please explain what is wrong been done by me.

Thanks

[mad fridgie]

are sure your calculated superheat is in C and F

[FreezerGeezer]

Mad Fridgie may be into seething there. The app cannot accept mixed imperial & metric values. Or alternatives either - eg you can't use Bar instead of kPa.

The other thing is: HVACBuddy is doing some calculations taking into effect all the data that you have input.
If you play around with the RA wet bulb or the condenser air-on temps you'll see the results change.
I believe that they're trying to be more scientific than simply subtracting SST from SPT.
I find the app somewhat confusing to be honest. And sometimes the diagnostic advice conflicts with the law or just good practice. Remember it's American and they have different working practices & laws there. As I understand it, you can still use R12 there, for example.