The cycle is whatever you set the timings for Recirculation (Reheating) and Exhaust (Purging). However, it’s better to Exhaust too often than not enough!
If you want to put the environment under slightly negative pressure the machine can go in the space being dried and you simply leave off the Outside Intake pipe and let the building space breathe naturally.
There are a number of ways to set the Drymatic II up to suit different situations and the recent launch of further connections expands the range of use further.