A flow generator and humidifier construction is described, including a flow generator construction adapted to reduce noise output compared to known flow generators of comparable size. The flow generator includes a chassis forming first and second muffler volumes and a venturi-shaped connection portion, and a metal/polymer composite material blower enclosure which suppresses noise from the blower. The flow generator may be programmed to include a reminder system including a menu from which the user may request a reminder to take specific action, e.g., replace a component, call a physician, and/or enter patient data card, etc.