A medical treatment system, such as a peritoneal dialysis system, may include a control system and other features to enhance patient comfort and ease of use. For example, the peritoneal dialysis system may include the control system that can adjust a volume of fluid infused into a peritoneal cavity to prevent an intraperitoneal fluid volume from exceeding a pre-determined amount. The control system can adjust by adding one or more therapy cycles, allowing for fill volumes during each cycle of the one or more therapy cycles to be reduced. The control system may continue to allow the fluid to drain from the peritoneal cavity as completely as possible before starting the next therapy cycle of the one or more therapy cycles. The control system may also adjust a dwell time of the fluid within the peritoneal cavity during the one or more therapy cycles in order to complete a therapy within a scheduled time period. A cycler may also be configured to have a heater control system that monitors both a temperature of a heating tray and a temperature of a bag of dialysis fluid in order to bring a temperature of the dialysis fluid rapidly to a specified temperature, with minimal temperature overshoot.