For maximum cleaning ability, turn the power and heat switches on for approximately two minutes before using your ProHeat. This will allow the heater to reach the desired temperature before the water and solution pass through it. If heated water is not required, the machine can be used without the heating switch activated. Just turn on the power switch and begin cleaning. For additional information please call Consumer Services toll free at 1-800-263-2535 Monday through Friday from 8 a.m. to 10 p.m. or Saturdays from 9 a.m. to 8 p.m. E.T.