There are four main reasons for heaters not being rated by room size which are:
The specific steps will depend on the type of thermostat control the heater has. Generally, to reset the safety PTC circuit, conduct the following steps:
Step 1. Remove the obstruction or situation that caused the unit to overheat.
Step 2. Turn the heater to the OFF setting (and turn the thermostat to HI)
Step 3. Unplug the heater and wait 5 to 10 minutes for the heater to cool down.
Step 4. Plug the heater back in and resume operation.
NOTE: If there is a thermostat, it should be turned to HI so that the heater will turn on when reset. With AccuTemp™ digital thermostats, the switch should first be turned to MANUAL. These steps are needed to ensure the heater will operate as soon as the reset time has elapsed. Otherwise, the heater might be reset but the user won't know because the thermostat setting is too high. Also, note that a few heaters have an automatic reset, where the unit does not need to be unplugged. Please check your instruction manual for your specific model. Finally, this feature will shut the heater off whether the heater tips over or not, as long as an overheat situation has occurred.
The fan speed should not change when you change the heat setting, the amount of heat being produced will change but the fan speed will remain the same.
NOTE: Fan speeds are held constant to ensure that the fan does not offset heat output.