Love seeing stuff like this. Pulled an evac on a system, cond unit, piping and evap. Rise test with Testo Smart came up to and flattened around just over 800 microns. As an experiment pulled down the system again isolating the cond unit and it came up on a rise and flattened at 640 ish. Opened condensing unit valves, you can see an immediate spike but began to flatten around 860ish. This tells us that the condensing unit is off gasing, no leak or it would just keep going. Off gasing what? Refrigerant boiling out of the oil or some moisture still left in the hygroscopic POE. Thoughts? On a system that has already been in service for some time, I don't get excited about a rise below 1000 microns. #teachme

Posted by HVAC Know It All at 2021-04-30 16:48:38 UTC