Ranco Temp Controller

[mrtian97]

I used 3 different temp gauge, the RkL, and 2 cheap temp gauge, all reading 79-80 while the Ranco is 86 and through time increased to 100. I know my tank doesn't have temp this high, room temp is maintained at 80 with AC and this was taken in the morning and at night (I am in Southern California so morning and night is pretty cool).
I think the temp sensor is bad, not sure why ETC Supply said they are fine.

 

[Lionfish Lair]

Same thing happened to me with my Reefkeeper elite. Had issues, I sent it off, they found nothing, but it's still not right despite what they said and I don't feel comfortable using it or selling it.

 

[CC13]

Same thing happened to me with my Reefkeeper elite. Had issues, I sent it off, they found nothing, but it's still not right despite what they said and I don't feel comfortable using it or selling it.

Do the Ranco's have to be calibrated at all?