An electric patio heater briefly needs a lot of power at start, called peak power. Sometimes the requested power is too high for your power group and the fuses blow. This risk is less with a heater with a built-in soft start. The soft start flattens the peak power, making it less likely that your stops will blow. So you don't have to make adjustments to your fuse box as quickly or purchase a separate soft starter to prevent peak power.