You can run system passively without a recovery pump. The process of passive recovery takes significantly longer. Our system relies on the recovery pump to move the solvent efficiently against pressure. Using temperature differentials between the collection base and the recovery tank you can passively recover. The process is limited by the rate your solvent can condense, and vapor pressure or blend (solvent ratios of butane/propane etc). The higher the temperature differential (i.e. the colder the recovery tank and the hotter the evaporation base) the faster the recovery process will occur.