... , not need to reset it only when you want to change the working time. b. It starts to work when plug in ... . When power off, it will stop, and continue to work when the power resume. If necessary, pls set the ... . c. It is mechanical timer, so minutes of error is possible, if accurate timer is necessary, pls be ... for heater: it is not safe for the heater to work continuously, and waste the power, if we have ...