I interviewed an ice machine rental and service company in Florida last week and demonstrated on several of the machines in their shop that the condenser fan was sucking air from the drain line, particularly on the Scotsman and Hoshizaki (see attached). After he seeing the demonstration, one of the service techs related an interesting story. He said he serviced a Hoshi rental at a local night club that was constantly getting dirty, so much so that even a week later it was filthy. After working on it and trying everything, he thought one day that maybe ambient air was floating up the drain line (bin was up at counter height) and getting the machine dirty? So, willing to try anything, he installed a P-trap on the bin drain line and low and behold, the problem of excessive dirtiness vanished. It was not until he saw the demonstration of negative air flows of a Hoshi sucking from the drain in his shop that he understood why the P-trap worked so well.
Anyone else had this experience??? Anyone putting P-traps on ice machine drains?