I understand that your Delonghi F600 smokes when you start it up for operation. I assume that the smoke is comming out of the top of the unit when it is shut.
There are three possible causes of this led/cover filter, food debris and oil break down.
The led/cover fitler is removeable and replaceable it is used to catch the oil of vapors that come out in the stem unit during frying, warmup and cooldown. The filter may be real dirty and need to be replaced. The filter can be replaced by clossing the lid and opening the filter door on the top of it. If the filter is no longer white it needs to be changed. The fiter set number is #DGI FK6 and can be purchased from DeLonghi for $14.99 at http://www.shopdelonghi.com/detail/DGI+FK6
If you notices little pieces of batter or black sand looking stuff in the bottom of your fryer the oil needs to be filtered. This should be done when the oil is cool and the unit is not plugged in. You can use cheese cloth or another filtering type cloth to filter the oil. You pour the oil from one item thru the cloth in to another item and discard what ever is caught in the cloth. The oil should be filter when you notice items stuff in the oil, no longer clear, or batter at the bottom of the oil.
The third possiblity is the oil is no longer valuable. The oil should be changed after 8 to 10 frings. Oil naturally breaks down over time just like the oil in your vehicle. The oil does not show signs of wear however, it should be changed after 8 to 10 uses.
If you have anymore questions about this fryer please post back to this thread and I will be happy to help you.
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