This paper describes experiences with the performance of a plate heat exchanger (PHE) installed at Mossman mill to preheat evaporator supply juice. In the 1994 crush, tests were conducted over a one month period to quantify the increase in evaporator capacity provided by the plate heater. When backflushing and on-line cleaning were performed, the PHE increased the set capacity by about 4% for the clean set, and by about 8% for the dirty set at the end of the two week operating period. The average increase in capacity over the operating period was about 6.0%. This paper models the performance of the evaporator set at Mossman Mill over the operating period and documents the plate heater operating procedures.