Generally, the heater will have slight smoke when the first burning, due to the oil was burning inside, after 10-20 mins, the smoke will disapear, if your heater still has heavy smoke, please check as below:

1, Oil quality

2, Oil volume, make sure the oil did not sucted from the bottom from the oil tank, the bottom oil is durty sometime, so it can not burn well.

3, Oil pump and oil pipes connect correctly.

4, try to dry burner, stop to provide the oil to the heater, then burn the oil in the burner finished.

Dry burner method:

1, Unplug the white fuel pipe from the fuel pump to the heater, and stop to provide the fuel for the heater running.

2, turn on the heater in a normal working mode.

3, Turn on /off the heater at least 5-10 times, and keep running for 5 mins each time, until the rest fuel in the burner is burned completely.

4, Plug the white fuel pipe from the fuel pump to the heater again.